Network Working Group N.B. Sopher
Internet-Draft O. Finkelman
Obsoletes: 8007 (if approved) Qwilt
Intended status: Standards Track S. Mishra
Expires: 9 January 2025 Verizon
J.K. Robertson
Qwilt
A. Arolovitch
Viasat
8 July 2024
Content Delivery Network Interconnection (CDNI) Control Interface /
Triggers 2nd Edition
draft-ietf-cdni-ci-triggers-rfc8007bis-14
Abstract
This document obsoletes RFC8007. The document describes the part of
Content Delivery Network Interconnection (CDNI) Control interface
that allows a CDN to trigger activity in an interconnected CDN that
is configured to deliver content on its behalf. The upstream CDN MAY
use this mechanism to request that the downstream CDN pre-position
metadata or content as well as request that it invalidate or purge
metadata or content. The upstream CDN MAY monitor the status of
activity that it has triggered in the downstream CDN.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 9 January 2025.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 6
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . 8
2.2. Scope of Triggered Activity . . . . . . . . . . . . . . . 9
2.2.1. Multiple Interconnected CDNs . . . . . . . . . . . . 9
2.3. Trigger Results . . . . . . . . . . . . . . . . . . . . . 10
3. Trigger Specification . . . . . . . . . . . . . . . . . . . . 10
3.1. Trigger Action . . . . . . . . . . . . . . . . . . . . . 11
3.2. Trigger Spec . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1. Trigger Subject . . . . . . . . . . . . . . . . . . . 12
3.2.2. Content URLs . . . . . . . . . . . . . . . . . . . . 13
3.3. Trigger Extensibility . . . . . . . . . . . . . . . . . . 13
4. Collections of Trigger Status Resources . . . . . . . . . . . 14
4.1. Filtered Collections by Trigger Status . . . . . . . . . 15
4.2. Filtered Collections by Trigger Label . . . . . . . . . . 15
5. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 15
5.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 16
5.2. Modifying Triggers . . . . . . . . . . . . . . . . . . . 17
5.3. Checking Status . . . . . . . . . . . . . . . . . . . . . 18
5.3.1. Polling Trigger Status Resource Collections . . . . . 18
5.3.2. Polling Trigger Status Resources . . . . . . . . . . 19
5.4. Cancelling Triggers . . . . . . . . . . . . . . . . . . . 19
5.5. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 20
5.6. Expiry of Trigger Status Resources . . . . . . . . . . . 21
5.7. Loop Detection and Prevention . . . . . . . . . . . . . . 21
5.8. Error Handling . . . . . . . . . . . . . . . . . . . . . 22
5.8.1. Error propagation . . . . . . . . . . . . . . . . . . 23
6. CI/T Object Properties and Encoding . . . . . . . . . . . . . 26
6.1. CI/T Objects . . . . . . . . . . . . . . . . . . . . . . 26
6.1.1. CI/T Create Command . . . . . . . . . . . . . . . . . 26
6.1.2. CI/T Modify Command . . . . . . . . . . . . . . . . . 27
6.1.3. Trigger Status Resources . . . . . . . . . . . . . . 27
6.1.4. Trigger Collections . . . . . . . . . . . . . . . . . 29
6.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 32
6.2.1. Trigger.v2 Specification . . . . . . . . . . . . . . 32
6.2.2. Generic Trigger Specs . . . . . . . . . . . . . . . . 33
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6.2.3. CI/T Trigger Extensions . . . . . . . . . . . . . . . 34
6.2.4. Absolute Time . . . . . . . . . . . . . . . . . . . . 39
6.2.5. Error.v2 Description . . . . . . . . . . . . . . . . 39
6.2.6. Trigger Status . . . . . . . . . . . . . . . . . . . 42
6.2.7. Error Code . . . . . . . . . . . . . . . . . . . . . 44
6.2.8. URL Type . . . . . . . . . . . . . . . . . . . . . . 45
6.2.9. ObjectList . . . . . . . . . . . . . . . . . . . . . 46
6.2.10. Trigger Label . . . . . . . . . . . . . . . . . . . . 52
7. Trigger Spec Objects . . . . . . . . . . . . . . . . . . . . 52
7.1. URLs Spec . . . . . . . . . . . . . . . . . . . . . . . . 52
7.2. CCIDs Spec . . . . . . . . . . . . . . . . . . . . . . . 53
7.3. URI Pattern Match Spec . . . . . . . . . . . . . . . . . 53
7.3.1. UriPatternMatch . . . . . . . . . . . . . . . . . . . 53
7.4. URI Regex Match Spec . . . . . . . . . . . . . . . . . . 55
7.4.1. RegexMatch . . . . . . . . . . . . . . . . . . . . . 55
7.5. Object List Spec . . . . . . . . . . . . . . . . . . . . 56
8. Trigger Extension Objects . . . . . . . . . . . . . . . . . . 57
8.1. LocationPolicy Extension . . . . . . . . . . . . . . . . 57
8.2. TimePolicy Extension . . . . . . . . . . . . . . . . . . 59
8.2.1. UTCWindow . . . . . . . . . . . . . . . . . . . . . . 61
8.3. ExecutionPolicy Extension . . . . . . . . . . . . . . . . 62
9. Footprint and Capabilities . . . . . . . . . . . . . . . . . 65
9.1. CI/T Endpoint Capability Object . . . . . . . . . . . . . 65
9.1.1. CI/T Endpoints Capability Object Serialization . . . 66
9.2. CI/T Trigger Scope Capability Object . . . . . . . . . . 67
9.2.1. CI/T Trigger Scope Capability Object Serialization . 68
9.3. CI/T Object List Type Capability Object . . . . . . . . . 69
9.3.1. CI/T Object List Type Capability Object
Serialization . . . . . . . . . . . . . . . . . . . . 69
9.4. CI/T Private URL Capability Object . . . . . . . . . . . 70
9.4.1. CI/T Private URL Type Capability Object
Serialization . . . . . . . . . . . . . . . . . . . . 70
9.5. CI/T Extended Status Capability Object . . . . . . . . . 71
9.5.1. CI/T Private URL Type Capability Object
Serialization . . . . . . . . . . . . . . . . . . . . 71
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 72
10.1. Creating Triggers . . . . . . . . . . . . . . . . . . . 72
10.1.1. Preposition . . . . . . . . . . . . . . . . . . . . 72
10.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 74
10.1.3. Invalidation with Regex . . . . . . . . . . . . . . 76
10.1.4. Preposition with ObjectLists . . . . . . . . . . . . 77
10.2. Examining Trigger Status . . . . . . . . . . . . . . . . 79
10.2.1. Collection of All Triggers . . . . . . . . . . . . . 79
10.2.2. Filtered Collections of Trigger Status Resources . . 80
10.2.3. Individual Trigger Status Resources . . . . . . . . 82
10.2.4. Polling for Changes in Status . . . . . . . . . . . 84
10.2.5. Deleting Trigger Status Resources . . . . . . . . . 87
10.2.6. Extensions with Error Propagation . . . . . . . . . 88
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11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 91
11.1. CDNI Payload Type Parameter Registrations . . . . . . . 91
11.1.1. CDNI ci-trigger-command.create.v2 Payload Type . . . 92
11.1.2. CDNI ci-trigger-command.modify.v2 Payload Type . . . 92
11.1.3. CDNI ci-trigger-status.v2 Payload Type . . . . . . . 92
11.1.4. CDNI FCI CI/T Payload Types . . . . . . . . . . . . 93
11.2. "CDNI CI/T Trigger Types" Registry For Trigger
Actions . . . . . . . . . . . . . . . . . . . . . . . . 93
11.3. "CDNI CI/T Trigger Specs" Registry . . . . . . . . . . . 94
11.4. "CDNI CI/T Trigger Subjects" Registry . . . . . . . . . 94
11.5. "CDNI CI/T Object List Types" Registry . . . . . . . . . 94
11.6. "CDNI CI/T Trigger Extensions" Registry . . . . . . . . 95
11.7. "CDNI CI/T Error Codes" Registry . . . . . . . . . . . . 95
11.8. "CDNI CI/T URL Types" Registry . . . . . . . . . . . . . 95
12. Security Considerations . . . . . . . . . . . . . . . . . . . 96
12.1. Authentication, Authorization, Confidentiality, Integrity
Protection . . . . . . . . . . . . . . . . . . . . . . . 96
12.2. Denial of Service . . . . . . . . . . . . . . . . . . . 97
12.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . 98
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 98
13.1. Normative References . . . . . . . . . . . . . . . . . . 98
13.2. Informative References . . . . . . . . . . . . . . . . . 99
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 101
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 101
1. Introduction
[RFC6707] introduces the problem scope for Content Delivery Network
Interconnection (CDNI) and lists the four categories of interfaces
that may be used to compose a CDNI solution (Control, Metadata,
Request Routing, and Logging).
[RFC7336] expands on the information provided in [RFC6707] and
describes each of the interfaces and the relationships between them
in more detail.
The CDNI Control Interface / Triggers 1st edition [RFC8007],
deprecated by this document, describes the "CI/T" interface -- "CDNI
Control interface / Triggers". It does not consider those parts of
the Control interface that relate to configuration, bootstrapping, or
authentication of CDN Interconnect interfaces. Section 4 of
[RFC7337] identifies the requirements specific to the CI/T interface;
requirements applicable to the CI/T interface are CI-1 to CI-6.
This document is a second edition of the CDNI Control Interface /
Triggers, which defines a new version, "v2", of the interface
objects. The new objects replace the trigger interface's main
objects, the "ci-trigger-command" object and its matching "ci-
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trigger-status" object to support RESTful [REST] semantics in a way
that improves the interface's flexibility, extensibility and
interoperability, and allows encoding the interface using OpenAPI.
The document also provides a Trigger Extension mechanism that MAY be
used to provide further instruction on the trigger execution.
Additionally, this second edition includes cascaded CDN error
propagation for improved trigger execution monitoring.
* Section 2 outlines the model for the CI/T interface at a high
level.
* Section 3 describes the trigger attributes used for specifying the
trigger's targets and for controlling the trigger's execution.
* Section 4 describes collections of Trigger Status Resources.
* Section 5 defines the web service provided by the downstream CDN.
* Section 6 lists properties of CI/T Commands and Status Resources.
* Section 7 describes the Trigger's Spec object.
* Section 8 describes the Trigger's Extensions object.
* Section 9 describes the FCI capabilities objects used to inform on
the supported CI/T-related capabilities.
* Section 10 contains example messages.
1.1. Terminology
This document reuses the terminology defined in [RFC6707] and uses
"uCDN" and "dCDN" as shorthand for "upstream CDN" and "downstream
CDN", respectively.
Additionally, the following terms are used throughout this document
and are defined as follows:
* HLS - HTTP Live Streaming
* DASH - Dynamic Adaptive Streaming Over HTTP
* MSS - Microsoft Smooth Streaming
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Model for CDNI Triggers
A CI/T Command, sent from uCDN to dCDN, is a request for the dCDN to
do some work (an "action") relating to data associated with content
requests originating from uCDN.
There are two types of CI/T Command: CI/T Create Trigger Command and
CI/T Modify Trigger Command. The CI/T Modify Command can be used to
request cancellation and/or modification of an earlier CI/T Trigger
Command.
A CI/T Trigger Action is of one of the following:
* preposition - used to instruct dCDN to fetch metadata from the
uCDN or content from any origin including uCDN.
* invalidate - used to instruct dCDN to revalidate specific metadata
or content before reusing it.
* purge - used to instruct dCDN to delete specific metadata or
content.
Note that additional CI/T Trigger Actions can be defined and
registered in the future.
The CI/T interface is a web service offered by dCDN. It allows CI/T
Commands to be issued and triggered activity to be tracked. The CI/T
interface builds on top of HTTP/1.1 [RFC9112]. References to URLs in
this document relate to HTTP/HTTPS URIs, as defined in Section 4.2 of
[RFC9110].
When dCDN accepts a CI/T Command, it creates a resource describing
the status of the triggered activity -- a Trigger Status Resource.
uCDN can poll Trigger Status Resources to monitor progress.
dCDN maintains at least one collection of Trigger Status Resources
for each uCDN. Each uCDN only has access to its own collections, the
locations of which are shared when CDNI is established.
To trigger activity in dCDN, uCDN POSTs a CI/T Command to the
collection of Trigger Status Resources. If dCDN accepts the CI/T
Trigger Create Command, it creates a new Trigger Status Resource and
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returns its location to uCDN. To monitor progress, uCDN can GET the
Trigger Status Resource. To request cancellation of a CI/T Trigger
Command, uCDN can POST to the collection of Trigger Status Resources
or simply DELETE the Trigger Status Resource.
Note that the version of the CI/T Command objects POSTed by uCDN MUST
match the version of CI/T Status Resource objects generated and
reported by dCDN. Thus, sending a [RFC8007] "ci-trigger-command"
object as the command generates a "ci-trigger-status" structured
resource to be reported, while sending a "ci-trigger-
command.create.v2" object generates a "ci-trigger-status.v2" object.
In addition to the collection of all Trigger Status Resources for the
uCDN, dCDN can maintain filtered views of that collection. These
filtered views are defined in Section 4 and include collections of
Trigger Status Resources filtered by Trigger Status or Trigger Label.
These collections provide a mechanism for polling the status of
multiple jobs.
Figure 1 is an example showing the basic message flow used by the
uCDN to trigger activity in dCDN and for uCDN to discover the status
of that activity. Only successful triggering is shown. Examples of
the messages are shown in Section 10.
uCDN dCDN
| (1) POST https://dcdn.example.com/triggers/uCDN |
[ ] --------------------------------------------------> [ ]--+
| [ ] | (2)
| (3) HTTP 201 Response [ ]<-+
[ ] <-------------------------------------------------- [ ]
| Loc: https://dcdn.example.com/triggers/uCDN/123 |
| |
. . .
. . .
. . .
| |
| (4) GET https://dcdn.example.com/triggers/uCDN/123 |
[ ] --------------------------------------------------> [ ]
| [ ]
| (5) HTTP 200 Trigger Status Resource [ ]
[ ] <-------------------------------------------------- [ ]
| |
| |
Figure 1: Basic CDNI Message Flow for Triggers
The steps in Figure 1 are as follows:
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1. uCDN triggers action in dCDN by POSTing a CI/T Command to a
collection of Trigger Status Resources --
"https://dcdn.example.com/triggers/uCDN". This URL was given to
uCDN when the CI/T interface was established.
2. dCDN authenticates the request, validates the CI/T Command, and,
if it accepts the request, creates a new Trigger Status Resource.
3. dCDN responds to uCDN with an HTTP 201 response status and the
location of the Trigger Status Resource.
4. uCDN MAY query, possibly repeatedly, the Trigger Status Resource
in dCDN.
5. dCDN responds to each query with the Trigger Status Resource,
describing the progress or results of the CI/T Trigger Command.
The remainder of this document describes the messages, Trigger Status
Resources, and collections of Trigger Status Resources in more
detail.
2.1. Timing of Triggered Activity
Timing of the execution of CI/T Commands is under dCDN's control,
including its start time and pacing of the activity in the network.
Instructions regarding this timing may be included in the trigger
using one of the Trigger Extension Objects defined in Section 8, such
as Section 8.3 and Section 8.2.
CI/T "invalidate" and "purge" commands MUST be applied to all data
acquired before the command was accepted by dCDN. dCDN SHOULD NOT
apply CI/T "invalidate" and "purge" commands to data acquired after
the CI/T Command was accepted, but this may not always be achievable,
so uCDN cannot count on that.
If uCDN wishes to invalidate or purge content and then immediately
pre-position replacement content at the same URLs, it SHOULD ensure
that dCDN has completed the invalidate/purge before initiating the
pre-positioning. Otherwise, there is a risk that the dCDN pre-
positions the new content, then immediately invalidates or purges it
(as a result of the two uCDN requests running in parallel).
Because the CI/T Command timing is under dCDN's control, dCDN
implementation can choose whether to apply CI/T "invalidate" and
"purge" commands to content acquisition that has already started when
the command is received.
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2.2. Scope of Triggered Activity
Each CI/T Command can operate on multiple metadata and content
elements, usually referred to by their URLs. These elements are
targeted by specifying both their subject (i.e., "metadata" or
"content") as well as specification method (e.g., URL Regexes) and
value.
Multiple representations of an HTTP resource may share the same URL.
CI/T Trigger Commands that invalidate or purge metadata or content
apply to all resource representations with matching URLs.
2.2.1. Multiple Interconnected CDNs
In a network of interconnected CDNs, a single uCDN will originate a
given item of metadata and associated content. It would possibly
distribute that metadata and content to more than one dCDN, which in
turn distributes that metadata and content to additional CDNs located
further downstream.
An intermediate CDN is dCDN that passes on CDNI Metadata and content
to dCDNs located further downstream.
A "diamond" configuration is one where dCDN can acquire metadata and
content originated in one uCDN from that uCDN itself and an
intermediate CDN, or via more than one intermediate CDN.
CI/T Commands originating in the single source uCDN affect metadata
and content in all dCDNs; however, in a diamond configuration, it may
not be possible for dCDN to determine from which uCDN it acquired
content. In this case, dCDN MUST allow each uCDN from which it may
have acquired the content to act upon that content using CI/T
Commands.
In all other cases, dCDN MUST reject CI/T Commands from uCDN that
attempts to act on another uCDN's content by using, for example,
responding with an HTTP 403 ("Forbidden").
Security considerations are discussed further in Section 12.
The diamond configuration may lead to inefficient interactions, but
the interactions are otherwise harmless. For example:
* When uCDN issues an "invalidate" CI/T Command, dCDN will receive
that command from multiple directly connected uCDNs. The dCDN may
schedule multiple such commands separately, and the last scheduled
command may affect content already revalidated following execution
of the "invalidate" command that was scheduled first.
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* If one of dCDN's directly connected uCDNs loses its rights to
distribute content, it may issue a CI/T "purge" command. That
purge may affect content dCDN could retain because it's
distributed by another directly connected uCDN. But, that content
can be reacquired by dCDN from the remaining uCDN.
* When uCDN originating an item of content issues a CI/T purge
followed by a pre-position, two directly connected uCDNs will pass
those commands to dCDN. That dCDN implementation need not merge
those operations or notice the repetition, in which case the purge
issued by one uCDN will be completed before the other. The first
uCDN to finish its purge may then forward the "preposition"
trigger, and content pre-positioned as a result might be affected
by the still-running purge issued by the other uCDN. However,
dCDN will reacquire that content as needed, or when it's asked to
pre-position the content by the second uCDN. dCDN implementation
could avoid this interaction by knowing which uCDN it acquired the
content from, or it could minimize the consequences by recording
the time at which the "invalidate"/"purge" command was received
and not applying it to content acquired after that time.
2.3. Trigger Results
Possible states for a Trigger Status Resource are defined in
Section 6.2.6.
The CI/T Trigger Command MUST NOT be reported as "complete" until all
operations have been completed successfully. The reasons for
failure, and URLs or patterns affected, SHOULD be enumerated in the
Trigger Status Resource. For more details, see Section 5.8.
If dCDN is also acting as uCDN in a cascade, it MUST forward CI/T
Commands to any dCDNs that may be affected. The CI/T Trigger Command
MUST NOT be reported as "complete" in a CDN until it is "complete" in
all of its dCDNs. If a CI/T Trigger Command is reported as
"processed" in any dCDN, intermediate CDNs MUST NOT report
"complete"; instead, they MUST also report "processed". A CI/T
Command MAY be reported as "failed" as soon as it fails in a CDN or
any of its dCDNs. A cancelled CI/T Trigger Command MUST be reported
as "cancelling" until it has been reported as "cancelled",
"complete", or "failed" by all dCDNs in a cascade.
3. Trigger Specification
The following attributes define the trigger execution.
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3.1. Trigger Action
Trigger Action is used in a Trigger Specification to describe trigger
actions. It was initially referred to in [RFC8007] as "Trigger
Type".
All trigger actions MUST be registered in the IANA "CDNI CI/T Trigger
Types" registry (see Section 11.2).
dCDN receiving a request containing a trigger action that it does not
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with "failed" status and the "errors" array
containing an Error.v2 Description with error "eunsupported" (see
Section 6.2.7).
The following trigger actions are defined by this document:
+=============+============================================+
| JSON String | Description |
+=============+============================================+
| preposition | A request for dCDN to acquire metadata or |
| | content. |
+-------------+--------------------------------------------+
| invalidate | A request for dCDN to invalidate metadata |
| | or content. After servicing this request, |
| | dCDN will not use the specified data |
| | without first revalidating it using, for |
| | example, an "If-None-Match" HTTP request. |
| | dCDN need not erase the associated data. |
+-------------+--------------------------------------------+
| purge | A request for dCDN to erase metadata or |
| | content. After servicing the request, the |
| | specified data MUST NOT be held on dCDN |
| | (dCDN should reacquire the metadata or |
| | content from uCDN if it needs it). |
+-------------+--------------------------------------------+
Table 1
3.2. Trigger Spec
The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a
set of properties and objects used by the trigger commands in order
to specify the targets upon which the trigger is applied. This
document modifies the trigger interface objects so it has a list of
trigger specs. Such structure improves the interface's extensibility
and flexibility. Furthermore, the document defines a generic trigger
spec object that acts as a wrapper for managing individual CDNI
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trigger specs in an opaque manner, allowing future extension of the
interface.
All trigger specs MUST be registered in the IANA "CDNI CI/T Trigger
Specs" registry (see Section 11.3).
dCDN receiving a request containing a trigger spec that it does not
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with "failed" status and the "errors" array
containing an Error.v2 Description with error "espec" (see
Section 6.2.7).
This document also defines an initial set of trigger spec objects and
registers them in the IANA "CDNI CI/T Trigger Specs" registry:
+====================+========================================+
| JSON String | Description |
+====================+========================================+
| urls | Allowing the specification of trigger |
| | targets via URLs. |
+--------------------+----------------------------------------+
| ccids | Allowing the specification of trigger |
| | targets via CCIDs content grouping, as |
| | defined in section 4.2.8 [RFC8006]. |
+--------------------+----------------------------------------+
| uri-pattern-match | Allowing the specification of trigger |
| | targets via [RFC3986] URI patterns. |
+--------------------+----------------------------------------+
| uri-regex-match | Allowing the specification of trigger |
| | targets via regexes matching their |
| | URI, as defined in Section 7.4. |
+--------------------+----------------------------------------+
| content-objectlist | Allowing the specification of trigger |
| | targets via an object list and an |
| | object list type. |
+--------------------+----------------------------------------+
Table 2
3.2.1. Trigger Subject
Because the scope of the trigger may relate to either metadata as
well as content, the "trigger spec object" also specifies the
trigger's target subject (i.e., metadata or content) against which to
match.
All trigger subjects MUST be registered in the IANA "CDNI CI/T
Trigger Subjects" registry (see Section 11.4).
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dCDN receiving a request containing a trigger subject that it does
not recognize or does not support MUST reject the request by creating
a Trigger Status Resource with "failed" status and the "errors" array
containing an Error.v2 Description with error "esubject" (see
Section 6.2.7).
This document also defines an initial set of trigger subject values
and registers them in the IANA "CDNI CI/T Trigger Subjects" registry:
+=============+====================================================+
| JSON String | Description |
+=============+====================================================+
| metadata | Indicating the trigger target specification refers |
| | to Metadata object, as defined at [RFC8006]. |
+-------------+----------------------------------------------------+
| content | Indicating the trigger target specification refers |
| | to client facing content. |
+-------------+----------------------------------------------------+
Table 3
3.2.2. Content URLs
Each CI/T Command usually refers to the targets by the target URLs,
using a "urls" trigger spec object or some aggregating spec such as
the "url-regex-match". If content URLs are transformed by an
intermediate CDN in a cascade, that intermediate CDN MUST similarly
transform URLs in CI/T Commands it passes to its dCDN.
When processing Trigger Specifications, CDNs MUST ignore the URL
scheme (HTTP or HTTPS) in comparing URLs. For example, for a CI/T
"invalidate" or "purge" command, content MUST be invalidated or
purged regardless of the protocol clients used to request it.
3.3. Trigger Extensibility
The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a
set of properties and objects used by the trigger commands. This 2nd
edition defines an extension mechanism to the triggers interface that
enables applications to add instructions for finer control over the
trigger execution, for example indicating a time window in which to
execute the trigger. This document specifies a generic trigger
extension object wrapper for managing individual CDNI trigger
extensions in an opaque manner.
All trigger extensions are optional, and it is thus the
responsibility of the extension specification to define a consistent
default behavior for the case the extension is not present.
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All trigger extensions MUST be registered in the IANA "CDNI CI/T
Trigger Extensions" registry (see Section 11.6).
This document also defines an initial set of trigger extension
objects and registers them in the IANA "CDNI CI/T Trigger Extensions"
registry:
+==================+=========================================+
| JSON String | Description |
+==================+=========================================+
| location-policy | Allowing the control over the locations |
| | in which the trigger is executed. |
+------------------+-----------------------------------------+
| time-policy | Allowing the scheduling of a trigger to |
| | run in a specific time window. |
+------------------+-----------------------------------------+
| execution-policy | Allowing the control over the order and |
| | timing in which triggers are executed. |
+------------------+-----------------------------------------+
Table 4
Example use cases
* Pre-position with cache location policy
* Purge content with cache location policy
* Pre-position at a specific time
* Purge by content acquisition time (e.g., purge all content
acquired in the past X hours)
4. Collections of Trigger Status Resources
As described in Section 2, Trigger Status Resources exist in dCDN to
report the status of activity triggered by each uCDN.
A collection of Trigger Status Resources is a resource that contains
a reference to each Trigger Status Resource in that collection. Note
that the collection may refer to Trigger Status Resources of triggers
from several versions of CI/T objects, i.e., a subsequent call for
the retrieval of the relevant trigger status may provide objects of
various MIME media types: ci-trigger-status as defined in [RFC8007],
ci-trigger-status.v2 defined in this document, or objects of future
CI/T objects versions, based on the CI/T command version used for the
creation of the trigger.
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dCDN MUST make a collection of uCDN's Trigger Status Resources
available to that uCDN. This collection includes all of the Trigger
Status Resources created for CI/T Commands from uCDN that have been
accepted by dCDN and have not yet been deleted by uCDN or expired and
removed by dCDN (as described in Section 5.5). Trigger Status
Resources belonging to uCDN MUST NOT be visible to any other CDN.
dCDN could, for example, achieve this by offering different
collection URLs to each uCDN and by filtering the response based on
uCDN with which the HTTP client is associated.
To trigger an activity in dCDN or to cancel a triggered activity, the
uCDN POSTs a CI/T Command to dCDN's collection of uCDN's Trigger
Status Resources.
To allow uCDN to check the status of multiple jobs in a single
request, dCDN MAY also maintain collections representing filtered
views of the collection of all Trigger Status Resources. These
filtered collections are "optional-to-implement", but if they are
implemented, dCDN MUST include links to them in the collection of all
Trigger Status Resources.
4.1. Filtered Collections by Trigger Status
dCDN MAY provide filtered collections per Trigger Status
(Section 6.2.6). If implemented, dCDN SHOULD provide a separate
filtered collection for every Trigger Status, and advertise these
collections in the collection of all Trigger Resources.
4.2. Filtered Collections by Trigger Label
dCDN MAY provide filtered collections per Trigger Label
(Section 6.2.10), as specified by uCDN in Section 6.2.1. If
implemented, dCDN SHOULD provide a separate filtered collection for
every unique Trigger Label, and advertise these collections in the
collection of all Trigger Resources.
5. CDNI Trigger Interface
This section describes an interface to enable uCDN to trigger
activity in dCDN.
The CI/T interface builds on top of HTTP, so dCDNs may make use of
any HTTP feature when implementing the CI/T interface. For example,
dCDN SHOULD make use of HTTP's caching mechanisms to indicate that a
requested response/representation has not been modified, reducing
uCDN's processing needed to determine whether the status of triggered
activity has changed.
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dCDNs MAY implement separate CI/T interfaces per Section 3.2.1, i.e.
one CI/T interface for trigger operations on metadata and another for
operations on content. In this case, dCDN MUST advertise separate
interface endpoints via Section 9.1.
All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST,
and DELETE methods as defined in [RFC9110].
The only representation specified in this document is JSON [RFC8259].
It MUST be supported by uCDN and by dCDN.
The URL of dCDN's collection of all Trigger Status Resources needs to
be either discovered by or configured in uCDN. The mechanism for
discovery of that URL is outside the scope of this document.
CI/T Commands are POSTed to dCDN's collection of all Trigger Status
Resources. If a CI/T Trigger Command is accepted by dCDN, dCDN
creates a new Trigger Status Resource and returns its URI to uCDN in
an HTTP 201 response. The triggered activity can then be monitored
by uCDN using that resource and the collections described in
Section 4.
The URI of each Trigger Status Resource is returned to uCDN when it
is created, and URIs of all Trigger Status Resources are listed in
dCDN's collection of all Trigger Status Resources. This means all
Trigger Status Resources can be discovered by uCDN, so dCDNs are free
to assign whatever structure they desire to the URIs for CI/T
resources. Therefore, uCDNs MUST NOT make any assumptions regarding
the structure of CI/T URIs or the mapping between CI/T objects and
their associated URIs. The URIs used in the examples in this
document are purely illustrative and are not intended to impose a
definitive structure on CI/T interface implementations.
5.1. Creating Triggers
To issue a CI/T Command, uCDN makes an HTTP POST to dCDN's collection
of all of uCDN's Trigger Status Resources. The request body of that
POST is a CI/T Command, as described in Section 6.1.1.
dCDN validates the CI/T Command. If the command is malformed or uCDN
does not have sufficient access rights, dCDN MUST either respond with
an appropriate 4xx HTTP error code and not create a Trigger Status
Resource or create a "failed" Trigger Status Resource containing an
appropriate Error.v2 Description.
When a CI/T Trigger Command is accepted, dCDN MUST create a new
Trigger Status Resource that will convey a specification of the CI/T
Command and its current status. The HTTP response to uCDN MUST have
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status code 201 and MUST convey the URI of the Trigger Status
Resource in the Location header field [RFC9110]. The HTTP response
SHOULD include the content of the newly created Trigger Status
Resource. This is particularly important in cases where the CI/T
Trigger Command has been completed immediately.
Once a Trigger Status Resource has been created, dCDN MUST NOT reuse
its URI, even after that Trigger Status Resource has been removed.
dCDN SHOULD track and report on the progress of CI/T Trigger Commands
using a Trigger Status Resource (Section 6.1.3). If the dCDN is not
able to do that, it MUST indicate that it has accepted the request
but will not be providing further status updates. To do this, it
sets the status of the Trigger Status Resource to "processed". In
this case, CI/T processing should continue as for a "complete"
request, so the Trigger Status Resource MUST be added to dCDN's
collection of complete Trigger Status Resources. dCDN SHOULD also
provide an estimated completion time for the request by using the
"etime" property of the Trigger Status Resource. This will allow
uCDN to schedule pre-positioning after an earlier delete of the same
URLs is expected to have finished.
If dCDN can track the execution of CI/T Commands and a CI/T Command
is queued by dCDN for later action, the "status" property of the
Trigger Status Resource MUST be "pending". Once processing has
started, the status MUST be "active". Finally, once the CI/T Command
is complete, the status MUST be set to "complete" or "failed".
A CI/T Trigger Command may result in no activity in dCDN if, for
example, it is an "invalidate" or "purge" request for datdCDN has not
yet acquired, or a "preposition" request for data that it has already
acquired and that is still valid. In this case, the status of the
Trigger Status Resource MUST be "processed" or "complete", and the
Trigger Status Resource MUST be added to dCDN's collection of
complete Trigger Status Resources.
Once created, Trigger Status Resources can be cancelled or deleted by
uCDN, but not modified. dCDN MUST reject PUT and POST requests from
uCDN to Trigger Status Resources by responding with an appropriate
HTTP status code -- for example, 405 ("Method Not Allowed").
5.2. Modifying Triggers
uCDN can request modification of an existing Trigger Command by
issuing CI/T Modify Trigger Command. Allowed modifications include
an update of the Trigger Command specification and change of state.
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dCDN MAY accept the request to update specification when the trigger
has "pending" status, i.e. the trigger has not been acted upon yet.
dCDN MAY accept the trigger status change request as long as:
* the requested state is "cancelled"
* the trigger has either "pending" or "active" status before the
request
Modification of existing triggers is useful for uCDN to correct an
error in trigger specification or trigger extension(s) that may
govern when the Trigger Command is to be executed.
dCDN MUST respond to the CI/T Modify Trigger Command appropriately.
For example, HTTP status code 200 ("OK") should be returned if the
modification has been processed, 202 ("Accepted") if the command has
been accepted but the modification is not fully complete yet, 404
("Not Found") when the Trigger Status Resource does not exist, 409
("Conflict") when the Trigger Status Resource is in a state that
doesn't allow the requested modification, 501 ("Not Implemented") if
modification is not supported by dCDN or an appropriate 4xx HTTP
error code in case of a malformed request.
5.3. Checking Status
uCDN has two ways to check the progress of CI/T Commands it has
issued to dCDN, as described in Sections Section 5.3.1 and
Section 5.3.2.
To allow uCDN to check for changes in the status of a Trigger Status
Resource or collection of Trigger Status Resources without refetching
the whole resource or collection, dCDN SHOULD include entity-tags
(ETags) for uCDN to use as cache validators, as defined in [RFC9110].
dCDN SHOULD use the cache control headers for responses to GETs for
Trigger Status Resources and Collections to indicate the frequency at
which it recommends that uCDN should poll for change.
5.3.1. Polling Trigger Status Resource Collections
uCDN can fetch the collection of its Trigger Status Resources or
filtered views of that collection.
This makes it possible to poll the status of all CI/T Trigger
Commands in a single request. If dCDN moves a Trigger Status
Resource from the active to the completed collection, uCDN can fetch
the result of that activity.
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When polling in this way, uCDN SHOULD use HTTP ETags to monitor for
change, rather than repeatedly fetching the whole collection. An
example of this is given in Section 10.2.4.
5.3.1.1. Extended View Trigger Status Resource Collections
If dCDN advertises support for extended status, uCDN MAY request the
extended Trigger Collection, which embeds all Trigger Status
resources in the collection itself, in addition to a list of Trigger
Status resource URLs. This support includes all types of Trigger
Status Resources Collections, including filtered collections.
uCDN SHOULD request the extended Trigger Collection view by passing
the query string parameter "status=extended" when requesting a
Trigger Status Resource Collection. dCDN SHOULD appropriately
respond to the request for extended status with HTTP Status 200
("OK") when such request can be satisfied, with error code 501 ("Not
Implemented") if the capability has not been implemented or
advertised, and 400 ("Bad Request") in case of an unrecognized query
parameters.
5.3.2. Polling Trigger Status Resources
uCDN has a URI provided by dCDN for each Trigger Status Resource it
has created. It may fetch that Trigger Status Resource at any time.
This can be used to retrieve progress information and to fetch the
result of the CI/T Command.
When polling in this way, uCDN SHOULD use HTTP ETags to monitor for
change, rather than repeatedly fetching the Trigger Status Resource.
5.4. Cancelling Triggers
uCDN can request cancellation of a trigger by issuing CI/T Modify
Trigger Command to the specific trigger's Trigger Status Resource URL
and setting the "desired-status" field to "cancelled".
dCDN is required to accept and respond to the CI/T Modify Command,
but the actual cancellation of a CI/T Trigger Command is optional-to-
implement.
dCDN MUST respond to the CI/T Modify Command appropriately -- for
example, with HTTP status code 200 ("OK") if the cancellation has
been processed and the CI/T Command is inactive, 202 ("Accepted") if
the command has been accepted but the CI/T Command remains active,
404 ("Not Found") when the Trigger Status Resource does not exist, or
501 ("Not Implemented") if cancellation is not supported by dCDN.
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If cancellation of a "pending" Trigger Status Resource is accepted by
dCDN, dCDN SHOULD NOT start the processing of that activity.
Requesting a cancellation of a trigger using a CI/T Modify Command
for a "pending" Trigger Status Resource does not, however, guarantee
that the corresponding activity will not be started, because uCDN
cannot control the timing of that activity. Processing could, for
example, start after the POST is sent by uCDN but before that request
is processed by dCDN.
If cancellation of an "active" or "processed" Trigger Status Resource
is accepted by dCDN, dCDN SHOULD stop processing the CI/T Command.
However, as with the cancellation of a "pending" CI/T Command, dCDN
does not guarantee this.
If the CI/T Command cannot be stopped immediately, the status in the
corresponding Trigger Status Resource MUST be set to "cancelling",
and the Trigger Status Resource MUST remain in the collection of
Trigger Status Resources for active CI/T Commands. If processing is
stopped before normal completion, the status value in the Trigger
Status Resource MUST be set to "cancelled", and the Trigger Status
Resource MUST be included in the collection of failed CI/T Trigger
Commands.
Cancellation of a "complete" or "failed" Trigger Status Resource
requires no processing in dCDN. Its status MUST NOT be changed to
"cancelled".
5.5. Deleting Triggers
uCDN can delete Trigger Status Resources at any time using the HTTP
DELETE method. As defined in the CDNI Control Interface / Triggers
1st edition [RFC8007], the effect is similar to cancellation, but no
Trigger Status Resource remains afterwards. Note that in cases where
the trigger's status before the deletion is not a terminal status
(i.e., "completed", "failed" or "cancelled"), uCDN would not have the
ability to further monitor the cancellation process and the final
status of the trigger. For this reason, it is recommended that the
trigger is cancelled (see Section 5.4) before trigger deletion and
deletion is only used on triggers with a terminal status.
Once deleted, the references to a Trigger Status Resource MUST be
removed from all Trigger Status Resource collections. Subsequent
requests to GET the deleted Trigger Status Resource SHOULD be
rejected by dCDN with an HTTP error.
If a "pending" Trigger Status Resource is deleted, dCDN SHOULD NOT
start the processing of that activity. Deleting a "pending" Trigger
Status Resource does not, however, guarantee that it has not started,
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because uCDN cannot control the timing of that activity. Processing
may, for example, start after the DELETE is sent by uCDN but before
that request is processed by dCDN.
If an "active" or "processed" Trigger Status Resource is deleted, the
dCDN SHOULD stop processing the CI/T Command. However, as with
deletion of a "pending" Trigger Status Resource, dCDN does not
guarantee this.
Deletion of a "complete" or "failed" Trigger Status Resource requires
no processing in dCDN other than deletion of the Trigger Status
Resource.
5.6. Expiry of Trigger Status Resources
dCDN can choose to automatically delete Trigger Status Resources
sometime after they become "complete", "processed", "failed", or
"cancelled". In this case, dCDN will remove the Trigger Status
Resource and respond to subsequent requests for it with an HTTP
error.
If dCDN does remove Trigger Status Resources automatically, it MUST
report the length of time after which it will do so, using a property
of the collection of all Trigger Status Resources. It is RECOMMENDED
that Trigger Status Resources are not automatically deleted by dCDN
for at least 24 hours after they become "complete", "processed",
"failed", or "cancelled".
To ensure that it can get the status of its Trigger Status Resources
for completed and failed CI/T Commands, it is RECOMMENDED that uCDN
polling interval is less than the time after which records for
completed activity will be deleted.
5.7. Loop Detection and Prevention
Given three CDNs, A, B, and C, if CDNs B and C delegate delivery of
CDN A's content to each other, CDN A's CI/T Commands could be passed
between CDNs B and C in a loop. More complex networks of CDNs could
contain similar loops involving more hops.
To prevent and detect such CI/T loops, each CDN uses a CDN Provider
ID (PID) to uniquely identify itself. In every CI/T Command it
originates or cascades, each CDN MUST append an array element
containing its CDN PID to a JSON array under an entry named "cdn-
path". When receiving CI/T Commands, dCDN MUST check the cdn-path
and reject any CI/T Command that already contains its own CDN PID in
the cdn-path. Transit CDNs MUST check the cdn-path and not cascade
the CI/T Command to dCDNs that are already listed in the cdn-path.
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The CDN PID consists of the two characters "AS" followed by the CDN
provider's Autonomous System number [RFC1930], then a colon (":") and
an additional qualifier that is used to guarantee uniqueness in case
a particular AS has multiple independent CDNs deployed -- for
example, "AS64496:0".
If the CDN provider has multiple ASes, the same AS number SHOULD be
used in all messages from that CDN provider, unless there are
multiple distinct CDNs.
If the CDNI Request Routing Redirection interface (RI) described in
[RFC7975] is implemented by dCDN, the CI/T interface and the RI
SHOULD use the same CDN PID.
5.8. Error Handling
dCDN can signal rejection of a CI/T Command using HTTP status codes
-- for example, 400 ("Bad Request") if the request is malformed, or
403 ("Forbidden") or 404 ("Not Found") if uCDN does not have
permission to issue CI/T Commands or it is trying to act on another
CDN's data.
If any part of the CI/T Trigger Command fails, the trigger SHOULD be
reported as "failed" once its activity is complete or if no further
errors will be reported. The "errors" property in the Trigger Status
Resource will be used to enumerate which actions failed and the
reasons for failure, and can be present while the Trigger Status
Resource is still "pending" or "active" if the CI/T Trigger Command
is still running for some URLs or patterns in the Trigger
Specification.
Once a request has been accepted, processing errors are reported in
the Trigger Status Resource using a list of Error.v2 Descriptions.
Each Error.v2 Description is used to report errors against one or
more of the URLs or patterns in the Trigger Specification.
If a Surrogate affected by a CI/T Trigger Command is offline in the
dCDN or dCDN is unable to pass a CI/T Command on to any of its
cascaded dCDNs:
* If the CI/T Command is abandoned by dCDN, dCDN SHOULD report an
error.
* A CI/T "invalidate" command may be reported as "complete" when
Surrogates that may have the data are offline. In this case,
Surrogates MUST NOT use the affected data without first
revalidating it when they are back online.
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* CI/T "preposition" and "purge" commands can be reported as
"processed" if affected caches are offline and the activity will
complete when they return to service.
* Otherwise, dCDN SHOULD keep the Trigger Status Resource in state
"pending" or "active" until either the CI/T Command is acted upon
or uCDN chooses to cancel it.
5.8.1. Error propagation
This subsection explains the mechanism for enabling uCDN to trace an
error back to dCDN in which it occurred. CDNI triggers may be
propagated over a chain of downstream CDNs. For example, an upstream
CDN A (uCDN-A) that is delegating to a downstream CDN B (dCDN-B) and
dCDN-B is delegating to a downstream CDN C (dCDN-C). Triggers sent
from uCDN-A to dCDN-B may be redistributed from dCDN-B to dCDN-C, and
errors can occur anywhere along the path. Therefore, it might be
essential for uCDN-A that sets the trigger, to be able to trace back
an error to the downstream CDN where it occurred. This document adds
a mechanism to propagate the PID of dCDN where the fault occurred,
back to the uCDN by adding the PID to the error.v2 description. When
dCDN-B propagates a trigger further to the downstream dCDN-C, it MUST
also propagate back the errors received in the trigger status
resource from dCDN-C by adding them to the errors array in its own
status resource to be sent back to the originating uCDN-A. While
propagating back the errors dCDN-B MAY also specify dCDN-C PID,
indicating to which CDN the error specifically relates. The trigger
originating upstream CDN then receives an array built of the errors
that occurred in all the CDNs along the execution path, where each
error MAY carry its own CDN identifier.
Figure 2 below is an example showing the message flow used by uCDN-A
to trigger activity in dCDN-B, followed by dCDN-C, as well as the
discovery of the status of that activity, including the Error
Propagation.
uCDN-A dCDN-B dCDN-C
| | |
| (1) POST | |
| https://dcdn-b.example.com | |
| /triggers/uCDN-A | |
[ ]--------------------------->[ ]--+ |
| [ ] | (2) |
| [ ]<-+ |
| (3) HTTP 201 Response. [ ] |
|<----------------------------[ ] |
| Loc: [ ] |
| https://dcdn-b.example.com [ ] (4) POST |
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| /triggers/uCDN-A/123 [ ] https://dcdn-c.example.com |
| [ ] /triggers/dCDN-B | (5)
| [ ]--------------------------->[ ]--+
| | [ ] |
| | [ ]<-+
| | (6) HTTP 201 Response. [ ]
| [ ]<---------------------------[ ]
| | Loc: |
| | https://dcdn-c.example.com |
| | /triggers/dCDN-B/456 |
| | |
| [ ]--+ |
| [ ] | (7.1) |
| [ ]<-+ [ ]--+
| | (7.2) [ ] |
| | [ ]<-+
| | |
. . .
. . .
. . .
| | (8) GET |
| | https://dcdn-c.example.com |
| | /triggers/dCDN-B/456 |
| [ ]--------------------------->[ ]
| | [ ]
| | (9) HTTP 200 [ ]
| | Trigger Status Resource [ ]
| [ ]<---------------------------[ ]
| | |
. . .
. . .
. . .
| (10) GET | |
| https://dcdn-b.example.com | |
| /triggers/uCDN-A/123 | |
[ ]--------------------------->[ ] |
| [ ] |
| (11) HTTP 200 [ ] |
| Trigger Status Resource [ ] |
[ ]<---------------------------[ ] |
Figure 2: CDNI Message Flow for Triggers, Including Error Propagation
The steps in Figure 2 are as follows:
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1. uCDN-A triggers an action in dCDN-B by POSTing a CI/T Command to
a collection of Trigger Status Resources "https://dcdn-
b.example.com/triggers/uCDN-A". This URL was given to uCDN-A
when the CI/T interface was established.
2. dCDN-B authenticates the request, validates the CI/T Command,
and, if it accepts the request, creates a new Trigger Status
Resource.
3. dCDN-B responds to uCDN-A with an HTTP 201 response status and
the location of the Trigger Status Resource.
4. dCDN-B triggers the action in dCDN-C by POSTing a CI/T Command
to a collection of Trigger Status Resources "https://dcdn-
c.example.com/triggers/dCDN-B". This URL was given to dCDN-B
when the CI/T interface was established.
5. dCDN-C authenticates the request, validates the CI/T Command,
and, if it accepts the request, creates a new Trigger Status
Resource.
6. dCDN-C responds to dCDN-B with an HTTP 201 response status and
the location of the Trigger Status Resource.
7. dCDN-C acts upon the CI/T Command. However, the command fails
at dCDN-C as, for example, the Trigger Specification contains an
"action type" that is not supported by dCDN-C. dCDN-C's action
is depicted by 7.2 in the diagram, while 7.1 shows dCDN-B acting
on its own command.
8. dCDN-B queries, possibly repeatedly, the Trigger Status Resource
in dCDN-C.
9. dCDN-C responds with the Trigger Status Resource, describing the
progress or results of the CI/T Trigger Command. In the
described flow, the returned Status is "failed", with an
Error.v2 Description Object holding "eunsupported" Error Code
reflecting the status response.
10. uCDN-A queries, possibly repeatedly, the Trigger Status Resource
in dCDN-B.
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11. dCDN-B responds with the Trigger Status Resource, describing the
progress or results of the CI/T Trigger Command. In the flow
described above, the returned Status is "failed", and the
"eunsupported" error received in the trigger status resource
from dCDN-C is propagated along with dCDN-C PID by adding it to
the errors array in dCDN-B's own status resource to be sent back
to the originating uCDN-A.
6. CI/T Object Properties and Encoding
The CI/T Create Trigger Command, CI/T Modify Trigger Command, Trigger
Status Resources, and Trigger Collections, as well as their
properties, are encoded using JSON, as defined in Sections
Section 6.1.1, Section 6.1.2, Section 6.1.3, and Section 6.1.4,
respectively. They MUST use the MIME media type "application/cdni",
with parameter "ptype" values as defined below and in Section 11.1.
Names in JSON are case-sensitive. The names and literal values
specified in the present document MUST always use lowercase.
JSON types, including "object", "array", "number", and "string", are
defined in [RFC8259].
Unrecognized name/value pairs in JSON objects SHOULD NOT be treated
as an error by either uCDN or dCDN. They SHOULD be ignored during
processing and passed on by dCDN to any further dCDNs in a cascade.
6.1. CI/T Objects
The top-level objects defined by the CI/T interface are described in
this section.
The encoding of values used by these objects is described in
Section 6.2.
6.1.1. CI/T Create Command
CI/T Create Trigger Command, which is used to create a new trigger,
MUST use a MIME media type of "application/cdni; ptype=ci-trigger-
command.create.v2".
A CI/T Create Trigger Command is encoded as a JSON object containing
the following name/value pairs:
Name: trigger-spec
Description: A specification of the trigger action and a set of
targets upon which to act.
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Value: A Trigger.v2 Specification, as defined in Section 6.2.1.
Mandatory: Yes.
Name: cdn-path
Description: The CDN PIDs of CDNs that have already issued the
CI/T Command to their dCDNs.
Value: A non-empty JSON array of JSON strings, where each
string is a CDN PID as defined in Section 5.7.
Mandatory: No.
6.1.2. CI/T Modify Command
CI/T Modify Command, which is used to modify an existing trigger,
MUST use a MIME media type of "application/cdni; ptype=ci-trigger-
command.modify.v2".
A CI/T Modify Trigger Command is encoded as a JSON object containing
the following name/value pairs:
Name: specs
Description: An updated specification of the trigger action and
a set of targets upon which to act.
Value: A Trigger.v2 Specification, as defined in Section 6.2.1.
Mandatory: No, but at least one of "specs" and "desired-status"
should be set.
Name: desired-status
Description: The target status for an existing trigger as
defined in Section 6.2.6
Value: JSON string.
Mandatory: No, but at least one of "specs" and "desired-status"
should be set.
6.1.3. Trigger Status Resources
Trigger Status Resources MUST use a MIME media type of "application/
cdni; ptype=ci-trigger-status.v2".
A Trigger Status Resource is encoded as a JSON object containing the
following name/value pairs:
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Name: trigger
Description: The Trigger Specification POSTed in the body of
the CI/T Command. Note that this need not be a byte-for-byte
copy. For example, in the JSON representation dCDN may re-
serialize the information differently.
Value: A Trigger.v2 Specification, as defined in Section 6.2.1.
Mandatory: Yes.
Name: ctime
Description: The time at which the CI/T Command was received by
the dCDN. The time is determined by dCDN; there is no
requirement to synchronize clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: Yes.
Name: mtime
Description: The time at which the Trigger Status Resource was
last modified. The time is determined by dCDN; there is no
requirement to synchronize clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: Yes.
Name: etime
Description: The estimate of the time at which dCDN expects to
complete the activity. Time is determined by dCDN; there is no
requirement to synchronize clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: No.
Name: status
Description: Current status of the triggered activity.
Value: Trigger Status, as defined in Section 6.2.6.
Mandatory: Yes.
Name: status-reason
Description: A human-readable explanation for the object
status.
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Value: A JSON string, the human-readable status reason.
Mandatory: No.
Name: errors
Description: Descriptions of errors that have occurred while
processing a Trigger Command.
Value: An array of Error.v2 Descriptions, as defined in
Section 6.2.5. An empty array is allowed and is equivalent to
omitting "errors" from the object.
Mandatory: No.
Name: objects
Description: List of objects derived by dCDN when processing a
Trigger Command.
Value: An array of ObjectList (Section 6.2.9) objects. dCDN
SHOULD provide the list of objects it used as input for
processing of Trigger Command with Section 7.5, provided that
dCDN advertised support for extended status (Section 9.5). An
empty array is allowed and is equivalent to omitting "objects"
from the Trigger Status. This field is intended to provide the
list of all objects used in processing. The objects that
failed to process SHOULD be specified using the Error.v2
Description resource.
Mandatory: No.
6.1.4. Trigger Collections
Trigger Collections MUST use a MIME media type of "application/cdni;
ptype=ci-trigger-collection".
A Trigger Collection is encoded as a JSON object containing the
following name/value pairs:
Name: triggers
Description: Links to Trigger Status Resources in the
collection.
Value: A JSON array of zero or more URLs, represented as JSON
strings.
Mandatory: Yes.
Name: staleresourcetime
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Description: The length of time for which dCDN guarantees to
keep a completed Trigger Status Resource. After this time,
dCDN SHOULD delete the Trigger Status Resource and all
references to it from collections.
Value: A JSON number, which must be a positive integer,
representing time in seconds.
Mandatory: Yes, in the collection of all Trigger Status
Resources if dCDN deletes stale entries. If the property is
present in the filtered collections, it MUST have the same
value as in the collection of all Trigger Status Resources.
Name: coll-state
Description: Array of all Section 6.1.4.2 objects.
Value: An array of JSON-encoded FilteredCollectionStatusLink
objects.
Mandatory: Mandatory in the collection of all Trigger Status
Resources, if dCDN implements the filtered collections.
Otherwise, optional.
Name: coll-label
Description: Array of all Section 6.1.4.1 objects.
Value: An array of JSON-encoded FilteredCollectionLabelLink
objects.
Mandatory: Mandatory in the collection of all Trigger Status
Resources, if dCDN implements the filtered collections.
Otherwise, optional.
Name: all-triggers
Description: Array of all Trigger Status objects in the
collection. Should be returned only when an extended trigger
collection view is requested as described in Section 5.3.1.1.
Value: An array of JSON-encoded Trigger Status objects.
Mandatory: No. The "all-triggers" SHOULD only be used by dCDN
that supports and advertises the appropriate extended status
for trigger collections (see Section 9.5 for details).
Name: cdn-id
Description: The CDN PID of dCDN.
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Value: A JSON string, dCDN's CDN PID, as defined in
Section 5.7.
Mandatory: Only in the collection of all Trigger Status
Resources, if dCDN implements the filtered collections.
Optional in the filtered collections (uCDN can always find
dCDN's cdn-id in the collection of all Trigger Status
Resources, but dCDN can choose to repeat that information in
its implementation of filtered collections).
6.1.4.1. Filtered Collections by Status Link
The Filtered Collections by Status Link object represents a link to a
filtered collection per Section 6.2.6. It is encoded as a JSON
object containing the following name/value pairs:
Name: status
Description: Trigger Status matching the filtered collection.
Value: A Trigger Status, as defined in Section 6.2.6.
Mandatory: Yes.
Name: collection
Description: Filtered collection URL corresponding to the
status.
Value: A URL represented as a JSON string.
Mandatory: Yes.
6.1.4.2. Filtered Collections by Label Link
The Filtered Collections by Label Link object represents a link to a
filtered collection per Section 6.2.10. It is encoded as a JSON
object containing the following name/value pairs:
Name: label
Description: Trigger Label matching the filtered collection.
Value: A Trigger Label, as defined in Section 6.2.10.
Mandatory: Yes.
Name: collection
Description: Filtered collection URL corresponding to the
label.
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Value: A URL represented as a JSON string.
Mandatory: Yes.
6.2. Properties of CI/T Objects
This section defines the values that can appear in the top-level
objects described in Section 6.1 and their encodings.
6.2.1. Trigger.v2 Specification
A Trigger.v2 Specification is encoded as a JSON object containing the
following name/value pairs:
An unrecognized name/value pair in the Trigger Specification object
contained in a CI/T Command SHOULD be preserved in the Trigger
Specification of any Trigger Status Resource it creates. Note that
the preferred method for extending the CI/T capabilities is by
defining new related trigger specs and/or trigger extensions, rather
than adding new properties to the Trigger.v2 object.
Name: action
Description: Defines the type of the CI/T Trigger Action.
Value: Trigger Action Type, as defined in Section 3.1.
Mandatory: Yes.
Name: specs
Description: Array of trigger specs representing the trigger's
targets.
Value: Array of GenericTriggerSpec objects (see
Section 6.2.2.1).
Mandatory: Yes. Furthermore, the list MUST NOT be empty.
Name: extensions
Description: Array of trigger extensions.
Value: Array of GenericTriggerExtension objects (see
Section 6.2.3.2).
Mandatory: No. The default is no extensions.
Name: labels
Description: Array of trigger labels.
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Value: Array of Trigger Labels (see Section 6.2.10).
Mandatory: No. The default is no labels.
6.2.2. Generic Trigger Specs
A "trigger.v2" object, as defined in Section 6.2.1, includes an array
of trigger spec objects. Each trigger spec object contains
properties that are used as trigger target selection directives for
dCDN when executing the trigger command, e.g., content URLs or
metadata URI patterns. Each such CDNI Trigger Spec is a
specialization of a CDNI GenericTriggerSpec object. The
GenericTriggerSpec object abstracts the basic information required
for trigger distribution from the specifics of any given property
(i.e., property semantics, enforcement options, etc.).
The semantics of the Trigger Specs list is additive, i.e., the
trigger applies to any object matching one of the listed specs.
6.2.2.1. Generic Spec Object
A GenericSpecObject object is a wrapper for managing individual CDNI
Trigger specs in an opaque manner.
It is encoded as a JSON object containing the following name/value
pairs:
Name: trigger-subject
Description: Case-insensitive CDNI Trigger subject.
Value: String containing the type of the subject matching the
generic-trigger-spec-value property, such as "content" or
"metadata" as defined in Section 3.2.1.
Mandatory: Yes.
Name: generic-trigger-spec-type
Description: Case-insensitive CDNI Trigger spec type.
Value: String containing the spec type of the object contained
in the generic-trigger-spec-value property (see table in
Section 3.2).
Mandatory: Yes.
Name: generic-trigger-spec-value
Description: A CDNI Trigger spec object.
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Value: Defined by the value of the generic-trigger-spec-type
property.
Mandatory: Yes.
The structure of a JSON serialized GenericTriggerSpec object,
containing a specific trigger spec is illustrated below:
{
"generic-trigger-spec-type":
<Type of this trigger spec>,
"generic-trigger-spec-value":
{
<properties of this trigger spec object>
},
"generic-trigger-spec-subject":
<Category of this trigger spec subject>
}
6.2.3. CI/T Trigger Extensions
A "trigger.v2" object, as defined in Section 6.2.1 includes an
optional array of trigger extension objects. A trigger extension
contains properties that are used as directives for dCDN when
executing the trigger command, e.g., location policies, time
policies, and so on. Each such CDNI Trigger extension is a
specialization of a CDNI GenericTriggerExtension object. The
GenericTriggerExtension object abstracts the basic information
required for trigger distribution from the specifics of any given
property (i.e., property semantics, enforcement options, etc.). All
trigger extensions are optional, and it is thus the responsibility of
the extension specification to define a consistent default behavior
for extensions supported by dCDN when not specified by uCDN.
6.2.3.1. Enforcement Options
The trigger enforcement options concept is in accordance with the
metadata enforcement options as defined in Section 3.2 of [RFC8006].
The GenericTriggerExtension object defines the properties contained
within it as well as whether or not the properties are "mandatory-to-
enforce". If dCDN does not understand or support a mandatory-to-
enforce property, dCDN MUST NOT execute the trigger command. If the
extension is not mandatory-to-enforce, then that
GenericTriggerExtension object can be safely ignored and the trigger
command can be processed in accordance with the rest of the CDNI
Trigger spec.
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Although a CDN MUST NOT execute a trigger command if a mandatory-to-
enforce extension cannot be enforced, it could still be safe to
redistribute that trigger (the "safe-to-redistribute" property) to
another CDN without modification. For example, in the cascaded CDN
case, a transit CDN (tCDN) could convey mandatory-to-enforce trigger
extension to dCDN. For a trigger extension that does not require
customization or translation (i.e., trigger extension that is safe-
to-redistribute), the data representation received off the wire MAY
be stored and redistributed without being understood or supported by
tCDN. However, for trigger extension that requires translation,
transparent redistribution of uCDN trigger values might not be
appropriate. Certain trigger extensions can be safely, though
perhaps not optimally, redistributed unmodified. For example, pre-
position command might be executed in suboptimal times for some
geographies if transparently redistributed, but it might still work.
Redistribution safety MUST be specified for each
GenericTriggerExtension listed. If a CDN does not understand or
support a given GenericTriggerExtension object that is not safe-to-
redistribute, the CDN MUST set the "incomprehensible" flag to true
for that GenericTriggerExtension object before redistributing it.
The "incomprehensible" flag signals to dCDN that trigger metadata was
not properly transformed by the tCDN. A CDN MUST NOT attempt to
execute a trigger with an extension that has been marked as
"incomprehensible" by uCDN.
tCDNs MUST NOT change the value of mandatory-to-enforce or safe-to-
redistribute when propagating a trigger to dCDN. Although a tCDN can
set the value of "incomprehensible" to true, a tCDN MUST NOT change
the value of "incomprehensible" from true to false.
Table 5 describes the action to be taken by a tCDN for the different
combinations of mandatory-to-enforce ("MtE") and safe-to-redistribute
("StR") properties when the tCDN either does or does not understand
the trigger extension object in question:
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+=======+=======+============+=================================+
| MtE | StR | Extension | Trigger action |
| | | object | |
| | | understood | |
| | | by tCDN | |
+=======+=======+============+=================================+
| False | True | True | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| False | True | False | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| False | False | False | Can execute. MUST set |
| | | | "incomprehensible" to true when |
| | | | redistributing. |
+-------+-------+------------+---------------------------------+
| False | False | True | Can execute. Can redistribute |
| | | | after transforming the trigger |
| | | | extension (if the CDN knows how |
| | | | to do so safely); otherwise, |
| | | | MUST set "incomprehensible" to |
| | | | true when redistributing. |
+-------+-------+------------+---------------------------------+
| True | True | True | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| True | True | False | MUST NOT execute but can |
| | | | redistribute. |
+-------+-------+------------+---------------------------------+
| True | False | True | Can execute. Can redistribute |
| | | | after transforming the trigger |
| | | | extension (if the CDN knows how |
| | | | to do so safely); otherwise, |
| | | | MUST set "incomprehensible" to |
| | | | true when redistributing. |
+-------+-------+------------+---------------------------------+
| True | False | False | MUST NOT serve. MUST set |
| | | | "incomprehensible" to true when |
| | | | redistributing. |
+-------+-------+------------+---------------------------------+
Table 5: Action to be taken by a tCDN for the different
combinations of MtE and StR properties
Table 6 describes the action to be taken by dCDN for the different
combinations of mandatory-to-enforce and "incomprehensible"
("Incomp") properties, when dCDN either does or does not understand
the trigger extension object in question:
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+=======+========+==================+==========================+
| MtE | Incomp | Extension object | Trigger action |
| | | understood by | |
| | | dCDN | |
+=======+========+==================+==========================+
| False | False | True | Can execute. |
+-------+--------+------------------+--------------------------+
| False | True | True | Can execute but MUST NOT |
| | | | interpret/apply any |
| | | | trigger extension marked |
| | | | as "incomprehensible". |
+-------+--------+------------------+--------------------------+
| False | False | False | Can execute. |
+-------+--------+------------------+--------------------------+
| False | True | False | Can execute but MUST NOT |
| | | | interpret/apply any |
| | | | trigger extension marked |
| | | | as "incomprehensible". |
+-------+--------+------------------+--------------------------+
| True | False | True | Can execute. |
+-------+--------+------------------+--------------------------+
| True | True | True | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
| True | False | False | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
| True | True | False | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
Table 6: Action to be taken by dCDN for the different
combinations of MtE and Incomp properties
6.2.3.2. GenericExtensionObject
A GenericTriggerExtension object is a wrapper for managing individual
CDNI Trigger extensions in an opaque manner.
It is encoded as a JSON object containing the following name/value
pairs:
Name: generic-trigger-extension-type
Description: Case-insensitive CDNI Trigger extension object
type.
Value: String containing the CDNI Extension Type [RFC7736] of
the object contained in the "generic-trigger-extension-value"
property (see table in Section 3.3).
Mandatory: Yes.
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Name: generic-trigger-extension-value
Description: CDNI Trigger extension object.
Value: Defined by the value of the "generic-trigger-extension-
type" property above.
Mandatory: Yes.
Name: mandatory-to-enforce
Description: Flag identifying whether or not the enforcement of
this trigger extension is mandatory.
Value: Boolean.
Mandatory: No. The default is to treat the trigger extension
as mandatory to enforce (i.e., a value of True)
Name: safe-to-redistribute
Description: Flag identifying whether or not this trigger
extension can be safely redistributed without modification,
even if the CDN fails to understand the extension.
Value: Boolean.
Mandatory: No. The default is to allow transparent
redistribution (i.e., a value of True).
Name: incomprehensible
Description: Flag identifying whether or not any CDN in the
chain of delegation has failed to understand and/or failed to
properly transform this trigger extension object. Note: This
flag only applies to trigger extension objects whose "safe-to-
redistribute" property has a value of False.
Value: Boolean.
Mandatory: No. The default is comprehensible (i.e., a value of
False).
The structure of a JSON serialized GenericTriggerExtension object
containing a specific trigger extension object is illustrated below:
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{
"generic-trigger-extension-type":
<Type of this trigger extension object>,
"generic-trigger-extension-value":
{
<properties of this trigger extension object>
},
"mandatory-to-enforce": <bool>,
"safe-to-redistribute": <bool>,
"incomprehensible": <bool>
}
6.2.4. Absolute Time
A JSON number, seconds since the UNIX epoch (00:00:00 UTC on 1
January 1970).
6.2.5. Error.v2 Description
An Error.v2 Description is used to report the failure of a CI/T
Command or failure in the activity it triggered. It is encoded as a
JSON object with the following name/value pairs:
Name: error
Value: Error Code, as defined in Section 6.2.7.
Mandatory: Yes.
Name: description
Description: A human-readable description of the error.
Value: A JSON string, the human-readable description.
Mandatory: No.
Name: specs
Description: Array of trigger spec objects from the
corresponding "specs" array at the Trigger Specification. Only
those specs to which the error applies are listed.
Value: Array Trigger Specifications, as defined in
Section 6.2.1, where each spec object MUST be exactly as they
appear in the request.
Mandatory: Yes.
Name: extensions
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Description: Array of trigger extension objects copied from the
corresponding "extensions" array from the Trigger
Specification. Only those extensions to which the error
applies are included, but those extensions MUST be exactly as
they appear in the request.
Value: Array of GenericTriggerExtension objects, where each
extension object is copied from the "extensions" array values
in the Trigger Specification.
Mandatory: No. The "extensions" array SHOULD be used only if
the error relates to extension objects. Property omission
should be interpreted as "the error is not related to any
extension".
Name: cdn-id
Description: The CDN PID of the CDN where the error occurred.
The "cdn-id" property is used by the originating uCDN or by the
propagating dCDN in order to distinguish in which CDN the error
occurred.
Value: A non-empty JSON string, where the string is a CDN PID
as defined in Section 5.7
Mandatory: Yes. dCDN may use its own CDN PID if it does not
want to expose the CDN PIDs of dCDNs.
Name: objects
Description: List of objects that failed to be processed during
execution of a Trigger Command.
Value: An array of ObjectList (Section 6.2.9) objects. dCDN
SHOULD provide the list of objects that it failed to process
during execution of a Trigger Command with Section 7.5,
provided that dCDN advertised support for extended status
(Section 9.5).
Mandatory: No. An empty array is allowed and is equivalent to
omitting "objects" from the Error.v2 Description.
Example of a JSON serialized Error.v2 Description object reporting a
malformed object list :
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{
"error": "econtent",
"description": "Failed to parse HLS object list",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "content-objectlist",
"generic-trigger-spec-value": {
"href": "https://www.example.com/hls/title/index.m3u8",
"type": "hls"
}
}
],
"objects": {
"href": "https://dcdn.com/triggers/2a544cd9/objects",
"type": "json"
}
"cdn": "AS64500:0"
}
Example of a JSON serialized Error.v2 Description object reporting an
unsupported extension object:
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{
"errors": [
{
"error": "eextension",
"description": "unrecognized extension <type>",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2"
]
}
}
],
"extensions": [
{
"generic-trigger-extension-type":
<type of this erroneous trigger extension object>,
"generic-trigger-extension-value": {
<properties of this erroneous trigger extension object>
}
}
],
"cdn": "AS64500:0"
}
]
}
6.2.6. Trigger Status
Trigger Status describes the current status of the triggered
activity. It MUST be one of the JSON strings in the following table:
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+=============+==============================+
| JSON String | Description |
+=============+==============================+
| pending | The CI/T Trigger Command has |
| | not yet been acted upon. |
+-------------+------------------------------+
| active | The CI/T Trigger Command is |
| | currently being acted |
+-------------+------------------------------+
| | upon. |
+-------------+------------------------------+
| complete | The CI/T Trigger Command |
| | completed successfully. |
+-------------+------------------------------+
| processed | The CI/T Trigger Command has |
| | been accepted, and no |
+-------------+------------------------------+
| | further status update will |
| | be made (can be used in |
+-------------+------------------------------+
| | cases where completion |
| | cannot be confirmed). |
+-------------+------------------------------+
| failed | The CI/T Trigger Command |
| | could not be completed. |
+-------------+------------------------------+
| cancelling | Processing of the CI/T |
| | Trigger Command is still in |
+-------------+------------------------------+
| | progress, but the CI/T |
| | Trigger Command has been |
+-------------+------------------------------+
| | cancelled by uCDN. |
+-------------+------------------------------+
| cancelled | The CI/T Trigger Command was |
| | cancelled by uCDN. |
+-------------+------------------------------+
Table 7
Along with the Trigger Status, the Trigger Status Resource object
includes a Status Reason property, allowing dCDN to provide
additional information for the trigger status. For example, dCDN may
indicate that the trigger status is "pending" due to one of the
execution prerequisites not being fulfilled. Such a prerequisite may
be specified via one of the extensions.
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6.2.7. Error Code
This type is used by dCDN to report failures in trigger processing.
All Error Codes MUST be registered in the IANA "CDNI CI/T Error
Codes" registry (see Section 11.7). Unknown Error Codes MUST be
treated as fatal errors, and the request MUST NOT be automatically
retried without modification.
The following Error Codes are defined by this document and MUST be
supported by an implementation of the CI/T v2 interface.
+==============+=================================+==============+
| Error Code | Description | Registration |
+==============+=================================+==============+
| emeta | dCDN was unable to acquire and/ | RFCthis |
| | or is not in possession of | |
| | metadata required to fulfill | |
| | the request. | |
+--------------+---------------------------------+--------------+
| econtent | dCDN was unable to acquire | RFCthis |
| | content (CI/T "preposition" | |
| | commands only). | |
+--------------+---------------------------------+--------------+
| eperm | uCDN does not have permission | RFCthis |
| | to issue the CI/T Command (for | |
| | example, the data is owned by | |
| | another CDN). | |
+--------------+---------------------------------+--------------+
| ereject | dCDN is not willing to fulfill | RFCthis |
| | the CI/T Command (for example, | |
| | a "preposition" request for | |
| | content at a time when dCDN | |
| | would not accept Request | |
| | Routing requests from uCDN). | |
+--------------+---------------------------------+--------------+
| ecdn | An internal error in dCDN or | RFCthis |
| | one of its dCDNs. | |
+--------------+---------------------------------+--------------+
| ecancelled | uCDN cancelled the request. | RFCthis |
+--------------+---------------------------------+--------------+
| eunsupported | The Trigger Specification | RFCthis |
| | contained an "action type" that | |
| | is not supported by dCDN. No | |
| | action was taken by dCDN other | |
| | than to create a Trigger Status | |
| | Resource in state "failed". | |
+--------------+---------------------------------+--------------+
| espec | An error occurred while parsing | RFCthis |
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| | a generic trigger spec, or that | |
| | the specific trigger spec is | |
| | not supported by the CDN. | |
+--------------+---------------------------------+--------------+
| esubject | An error occurred while parsing | RFCthis |
| | a trigger subject, or that the | |
| | specific trigger subject is not | |
| | supported by the CDN. | |
+--------------+---------------------------------+--------------+
| eextension | An error occurred while parsing | RFCthis |
| | a generic trigger extension, or | |
| | that the specific extension is | |
| | not supported by the CDN. | |
+--------------+---------------------------------+--------------+
Table 8
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
6.2.8. URL Type
This type is used by uCDN to indicate how to interpret URLs
referenced by trigger specs that use URLs, such as Section 7.1,
Section 7.3, Section 7.4 and Section 7.5.
One option for uCDN to use in Trigger Commands is published URLs,
which are used by end users. When using this URL type, uCDN MUST
provide configuration metadata objects related to these URLs before
creating a trigger option referencing these URLs. When this is not
the case, dCDN MUST return the error code "emeta".
When processing published URLs in "preposition" Trigger Action, dCDN
MUST invoke processing of metadata objects it would have invoked in
content acquisition to satisfy an end-user request, e.g.
SourceMetadata (see Section 4.2.1 of [RFC8006]).
Another type of URL in common use is a private URL, which is based on
cache keys that are dynamically constructed via lightweight
processing of various properties of the HTTP request and/or response.
As an example, an origin might specify a cache key as a value
returned in a specific HTTP response header.
As an example, uCDN may prefer to use such private URLs in "purge" or
"invalidate" Trigger Actions to simplify processing.
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dCDNs implementing the CI/T Interface MUST support the "published"
URL type. dCDN MAY support the additional "private" URL type. In
this case, dCDN SHOULD advertise the private URL type support via FCI
using Section 9.4. If the private URL is not supported by dCDN, it
SHOULD reject the Trigger Command using "eunsupported" Error Code.
If both URL types are supported by dCDN, uCDN MUST use only one URL
type in each Trigger Command.
The following URL types are defined by this document and MUST be
supported by the implementation of the CI/T interface:
+===========+==================================+==============+
| URL Type | Description | Registration |
+===========+==================================+==============+
| published | Published URL used by end users | RFCthis |
| | to access content | |
+-----------+----------------------------------+--------------+
| private | Private URLs used by dCDN to | RFCthis |
| | look up content objects in cache | |
+-----------+----------------------------------+--------------+
Table 9
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
6.2.9. ObjectList
ObjectList is a metadata object describing lists of objects that can
be used in the context of CI/T v2 trigger spec, trigger status
resources and other contexts as required. The ObjectList object can
either embed the lists of objects or point to external URL(s) that
hold such lists. ObjectList allows the specification of an object
list type, providing instructions on the interpretation of the object
list format.
ObjectLists MAY be recursive, i.e. including references to secondary
manifests, including references to HLS, MPEG-DASH or MSS manifests as
well as additional JSON-encoded ObjectLists, etc. The party
consuming the object list MUST parse all recursions based on the
object list type property. When doing so, the consuming party should
also detect potential loops when the descendant ObjectList points
back to the parent ObjectList.
In the case of uCDN accessing ObjectList objects referencing external
URLs published by dCDN, both parties should comply with the CI/T
interface security requirements (see Section 12.1 for details). When
dCDN accesses external URLs referenced by ObjectLists supplied by
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uCDN, for example as part of Trigger Spec, dCDN MUST match these URLs
with source metadata objects, published by uCDN, such as
SourceMetadata objects specified in Section 4.2.1 of [RFC8006], and
use these metadata objects for content acquisition if a match was
found.
ObjectLists MAY combine regular objects and secondary ObjectLists in
the same object. Please note that when embedding non-JSON object
lists directly in ObjectList, absolute URLs MUST be provided at all
times and the text SHOULD be encoded in accordance with the JSON
grammar specification [ECMA404], including explicit newline encoding.
When uCDN accesses ObjectList metadata resources published by uCDN,
the same interface authentication and authorization requirements
would apply, as when accessing the interface itself.
ObjectList is encoded as an array of per-object records in JSON
format as follows:
External HLS manifest:
[
{
"href": "https://example.com/hls/a36f764e/index.m3u8",
"type": "hls"
}
]
External object list in text format:
[
{
"href": "https://example.com/hls/35cdc008/assets",
"type": "text"
}
]
List of external manifests and objects of mixed types:
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[
{
"href": "https://example.com/hls/35cdc008/index.m3u8",
"type": "hls"
},
{
"href": "https://example.com/dash/35cdc008/main.mpd",
"type": "dash"
},
{
"href": "https://example.com/dash/35cdc008/files.json",
"type": "json"
}
]
Embedded JSON-encoded object list:
[
{
"data": [
{
"href": "https://example.com/hls/35cdc008/index.m3u8",
"type": "hls"
},
{
"href":"https://example.com/dash/35cdc008/main.mpd",
"type": "dash"
},
{
"href": "https://example.com/img/35cdc008/thumb-l.jpg",
"size": 10260
},
{
"href": "https://example.com/img/35cdc008/thumb-s.jpg",
"size": 1453
}],
"type": "json"
}
]
Embedded HLS manifest:
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[
{
"data":
"#EXTM3U\n
#EXT-X-STREAM-INF:BANDWIDTH=150000,RESOLUTION=416x234\n
http://example.com/hls/35cdc008/low/index.m3u8\n
#EXT-X-STREAM-INF:BANDWIDTH=240000,RESOLUTION=416x234\n
http://example.com/hls/35cdc008/lo_mid/index.m3u8\n
#EXT-X-STREAM-INF:BANDWIDTH=440000,RESOLUTION=416x234\n
http://example.com/hls/35cdc008/hi_mid/index.m3u8\n
#EXT-X-STREAM-INF:BANDWIDTH=640000,RESOLUTION=640x360\n
http://example.com/hls/35cdc008/high/index.m3u8\n
#EXT-X-STREAM-INF:BANDWIDTH=64000\n
http://example.com/hls/35cdc008/audio/index.m3u8\n",
"type": "hls"
}
}
The ObjectList properties are as follows:
Name: data
Description: List of objects in one of the recognized formats.
Value: JSON String.
Mandatory: No. Either "data" or "href" MUST be set.
Name: href
Description: URL pointing to an external object list or object
in one of the recognized formats.
Value: A URL represented as a JSON String
Mandatory: No. Either "data" or "href" MUST be set.
Name: type
Description: Object list type to be used when parsing and
interpreting this object list. By default, each record in the
list is assumed to represent an object that does not require
additional processing.
Value: ObjectListType (see Section 6.2.9).
Mandatory: Yes.
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6.2.9.1. ObjectList Type
ObjectListType objects are used to specify the registered type of
ObjectList objects (see Section 11.5), used in Trigger Spec, Trigger
Status and Error.v2 Description objects.
The following table defines the initial ObjectListType JSON string
values
+========+==================+===============+===============+
| JSON | Description | Specification | Protocol |
| string | | | Specification |
+========+==================+===============+===============+
| hls | HTTP Live | RFCthis | RFC 8216 |
| | Streaming | | [RFC8216] |
+--------+------------------+---------------+---------------+
| mss | Microsoft Smooth | RFCthis | MSS [MSS] |
| | Streaming | | |
+--------+------------------+---------------+---------------+
| dash | Dynamic Adaptive | RFCthis | MPEG-DASH |
| | Streaming over | | [MPEG-DASH] |
| | HTTP (MPEG-DASH) | | |
+--------+------------------+---------------+---------------+
| json | JSON serialized | RFCthis | JSON (Section |
| | object list | | 6.2.9.2) |
+--------+------------------+---------------+---------------+
| text | Object list in | RFCthis | Text (Section |
| | text format | | 6.2.9.3) |
+--------+------------------+---------------+---------------+
Table 10
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
6.2.9.2. JSON Serialized Object List
This ObjectList type specifies a collection of objects encoded in
JSON format, where each entry is encoded as an ObjectEntry
(Section 6.2.9.4) object. The entries in the JSON object list MAY
have an object list type specified, allowing for a recursive object
list structure.
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6.2.9.3. Text Object List
Unlike the JSON Serialized Object List (Section 6.2.9.2), the text-
based object list will not support a recursive object list structure
and every object specified in it SHOULD be downloaded without
additional processing.
6.2.9.4. ObjectEntry
ObjectEntry is a metadata object describing an object and its
associated metadata, to be used in JSON-encoded ObjectList
(Section 6.2.9) objects.
The following is an example of JSON serialized ObjectEntry objects:
[
{
"href": "https://example.com/hls/35cdc008/index.m3u8",
"type": "hls"
},
{
"href": "https://example.com/dash/35cdc008/main.mpd",
"type": "dash"
},
{
"href": "https://example.com/img/35cdc008/thumb-l.jpg",
"size": 102600
},
{
"href": "https://example.com/img/35cdc008/thumb-s.jpg",
"size": 14535
},
]
The ObjectEntry properties are as follows:
Name: href
Description: Object URL
Value: A URL represented as a JSON string.
Mandatory: Yes.
Name: type
Description: ObjectList type to be used when processing this
object. By default, ObjectEntry object is assumed to represent
an object and does not require additional processing.
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Value: ObjectListType (see Section 6.2.9.1).
Mandatory: No.
Name: size
Description: Object size, in bytes. Can be used to decide to
download the object based on size. For example, dCDN may
ignore objects that are too small or too large.
Value: Integer.
Mandatory: No.
6.2.10. Trigger Label
A JSON string. Labels SHOULD be unique per trigger.
7. Trigger Spec Objects
The objects defined below are intended to be used in the
GenericTriggerSpec object's generic-trigger-spec-value field as
defined in Section 6.2.2.1. As such all these trigger specs are
registered in the IANA "CDNI CI/T Trigger Specs" registry (see
Section 11.3).
7.1. URLs Spec
The "urls" spec type allows uCDN to manage uCDN content or metadata
objects held by dCDN based on the objects' URLs.
The URLs spec is encoded as a JSON object containing the following
name/value pairs:
Name: urls
Description: An array of URLs over which the trigger MUST be
executed.
Value: A JSON array of URLs represented as JSON strings.
Mandatory: Yes.
Name: url-type
Description: Type of URL used.
Value: URL Type as defined in Section 6.2.8.
Mandatory: No. When omitted or empty, "published" URL type is
assumed.
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Below is an example of a JSON serialized URLs spec object, matching
the metadata at metadata.example.com/a/b/c.
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
],
"url-type": "published"
}
}
7.2. CCIDs Spec
The "ccids" spec type allows uCDN to specify the Content Collection
IDentifier (CCID) of content to which the trigger applies. The CCID
is a grouping of content as defined by [RFC8006]. The "ccids" spec
type is valid only for the content spec subject (see Section 3.2.1).
CCIDs spec is encoded as a JSON object containing the following name/
value pairs:
Name: ccids
Description: An array of Content Collection IDentifiers over
which the trigger MUST be executed.
Value: A JSON array of strings, where each string is a Content
Collection IDentifier.
Mandatory: Yes.
7.3. URI Pattern Match Spec
The "uri-pattern-match" spec type allows uCDN to manage uCDN content
or metadata objects held by dCDN based on the objects' URI pattern.
The value is a UriPatternMatch object, as defined in Section 7.3.1.
7.3.1. UriPatternMatch
A UriPatternMatch consists of a string pattern to match against a
URI, and flags describing the type of match.
It is encoded as a JSON object containing the following name/value
pairs:
Name: pattern
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Description: A pattern for URI matching.
Value: A JSON string representing the pattern. The pattern can
contain the wildcards "*" and "?", where "*" matches any
sequence of [RFC3986] pchar or "/" characters (including the
empty string) and "?" matches exactly one [RFC3986] pchar
character. The three literals "$", "*" and "?" MUST be
escaped as "$$", "$*" and "$?" (where "$" is the designated
escape character). All other characters are treated as
literals.
Mandatory: Yes.
Name: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Value: One of the JSON values "true" (the matching is case
sensitive) or "false" (the matching is case insensitive).
Mandatory: No; default is "false", i.e., a case-insensitive
match.
Name: match-query-string
Description: Flag indicating whether to include the query part
of the URI when compared against the pattern.
Value: One of the JSON values "true" (the full URI, including
the query part, should be compared against the given pattern)
or "false" (the query part of the URI should be dropped before
comparison with the given pattern).
Mandatory: No; default is "false". The query part of the URI
should be dropped before comparison with the given pattern.
Name: url-type
Description: Type of URLs to match.
Value: URL Type as defined in Section 6.2.8.
Mandatory: No. When omitted or empty, "published" URL type is
assumed.
Example of case-sensitive prefix match against
"https://www.example.com/trailers/":
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{
"pattern": "https://www.example.com/trailers/*",
"case-sensitive": true
}
7.4. URI Regex Match Spec
The "uri-regex-match" spec type allows uCDN to manage content or
metadata objects held by dCDN based on the objects' URI regex.
7.4.1. RegexMatch
A RegexMatch consists of a regular expression string a URI is matched
against, and flags describing the type of match. It is encoded as a
JSON object with the following properties:
Name: regex
Description: A regular expression for URI matching.
Value: A regular expression to match against the URI, i.e.,
against the path-absolute and the query string parameters
[RFC3986]. The regular expression string MUST be compatible
with POSIX [POSIX.1] Section 9 Extended Regular Expressions.
This regular expression MUST be evaluated in the POSIX locale
(POSIX [POSIX.1] Section 7.2).
Note: Because '\' has a special meaning in JSON [RFC8259] as
the escape character within JSON strings, the regular
expression character '\' MUST be escaped as '\\'.
Mandatory: Yes.
Name: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Value: JSON boolean. Either "true" (the matching is case-
sensitive) or "false" (the matching is case insensitive).
Mandatory: No; default is "false", i.e., a case-insensitive
match.
Name: match-query-string
Description: Flag indicating whether to include the query part
of the URI when compared against the regex.
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Value: JSON Boolean. Either "true" (the full URI, including
the query part, should be compared against the regex) or
"false" (the query part of the URI should be dropped before
comparison with the given regex).
Mandatory: No; default is "false". The query part of the URI
MUST be dropped before comparison with the given regex. This
makes the regular expression simpler and safer for cases in
which the query parameters are not relevant for the match.
Name: url-type
Description: Type of URLs to match against.
Value: URL Type as defined in Section 6.2.8.
Mandatory: No. When omitted or empty, "published" URL type is
assumed.
Example of a case-sensitive, no query parameters, regex match
against:
"^(https:\/\/video\.example\.com)\/([a-z])\/
movie1\/([1-7])\/*(index.m3u8|\d{3}.ts)$"
{
"regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\\/
movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
This regex matches URLs of the domain "video.example.com" where the
path structure is /(single lower case letter)/(name-of-title)/(single
digit between 1 to 7)/(index.m3u8 or a 3 digit number with ts
extension). For example:
https://video.example.com/d/movie1/5/index.m3u8
or
https://video.example.com/k/movie1/4/013.ts
7.5. Object List Spec
The "objectlist" spec type allows uCDN to manage content held by dCDN
based on structured object lists. The Object List spec type is valid
only for the content spec subject (see Section 3.2.1).
An object list is encoded as an ObjectList (Section 6.2.9) object.
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8. Trigger Extension Objects
The objects defined below are intended to be used in the
GenericTriggerExtension object's generic-trigger-extension-value
field as defined in Section 6.2.3.2, and their generic-trigger-
extension-type property MUST be set to the appropriate Extension Type
as defined in Section 3.3.
8.1. LocationPolicy Extension
A content operation may be relevant for a specific geographical
region or need to be excluded from a specific region. In this case,
the trigger should be applied only to parts of the network that are
either "included" or "not excluded" by the location policy. Note
that the restrictions here are on the cache location rather than the
client location.
The LocationPolicy object defines which CDN or cache locations for
which the trigger command is relevant.
Example use cases:
* Pre-position: Certain contracts allow for pre-positioning or
availability of contracts in all regions except for certain
excluded regions in the world, including caches. For example,
some content cannot ever knowingly touch servers in a specific
country, including cached content. Therefore, these regions MUST
be excluded from a pre-positioning operation.
* Purge: In certain cases, content may have been located on servers
in regions where the content must not reside. In such cases, a
purge operation to remove content specifically from that region is
required.
Object specification:
Name: locations
Description: An Access List that allows or denies (blocks) the
trigger execution per cache location.
Value: Array of LocationRule objects (see Section 4.2.2.1 of
[RFC8006]).
Mandatory: Yes.
Name: url-type
Description: Type of URL used in the ObjectList(s).
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Value: URL Type as defined in Section 6.2.8.
Mandatory: No. When omitted or empty, the "published" URL type
is assumed.
If a location policy object is not listed within the trigger command,
the default behavior is to execute the trigger in all available
caches and locations of dCDN.
The trigger command is allowed, or denied, for a specific cache
location according to the action of the first location whose
footprint matches that cache's location. If two or more footprints
overlap, the first footprint that matches against the cache's
location determines the action a CDN MUST take. If the "locations"
property is an empty list or if none of the listed footprints match
the location of a specific cache location, then the result is
equivalent to a "deny" action.
The following is an example of a JSON serialized generic trigger
extension object containing a location policy object that allows the
trigger execution in the US but blocks its execution in Canada:
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{
"generic-trigger-extension-type": "location-policy",
"generic-trigger-extension-value":
{
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
},
{
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["ca"]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true,
"incomprehensible": false
}
8.2. TimePolicy Extension
uCDN may wish to perform content management operations on dCDN on a
specific schedule. The TimePolicy extension allows uCDN to instruct
dCDN to execute the trigger command in a desired time window. For
example, a content provider that wishes to pre-populate a new episode
at off-peak time so that it would be ready on caches at prime time
when the episode is released for viewing. A scheduled operation
enables uCDN to direct dCDN in what time frame to execute the
trigger.
uCDN may wish to schedule a trigger such that dCDN will execute it in
local time, as it is measured in each region. For example, uCDN may
wish dCDN to pull the content at off-peak hours, between 2AM-4AM,
however, as a CDN is distributed across multiple time zones, the UTC
definition of 2AM depends on the actual location.
We define two alternatives for localized scheduling:
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* Regional schedule: When used in conjunction with the Location
Policy defined in Section 8.1, uCDN can trigger separate commands
for different geographical regions, for each region using a
different schedule. This allows uCDN to control the execution
time per region.
* Local Time schedule: We introduce a "local time" version for
Internet timestamps that follows the notation for local time as
defined in Section 4.2.2 of [ISO8601]. When local time is used,
that dCDN SHOULD execute the triggers at different absolute times,
according to the local time of each execution location.
Object specification:
Name: unix-time-window
Description: A UNIX epoch time window in which the trigger
SHOULD be executed.
Value: TimeWindow object using UNIX epoch timestamps (see
Section 4.2.3.2 of [RFC8006]).
Mandatory: No, but exactly one of "unixEpochWindow" or
"utcWindow" MUST be present.
Name: utc-window
Description: A UTC time window in which the trigger SHOULD be
executed.
Value: UTCWindow object as defined in Section 8.2.1.
Mandatory: No, but exactly one of "unixEpochWindow" or
"utcWindow" MUST be present.
If a time policy object is not listed within the trigger command, the
default behavior is to execute the trigger in a time frame most
suitable to dCDN taking under consideration other constraints and /
or obligations.
Example of a JSON serialized generic trigger extension object
containing a time policy object that schedules the trigger execution
to a window between 09:00 01/01/2000 UTC and 17:00 01/01/2000 UTC,
using the "unix-time-window" property:
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{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value":
{
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true,
"incomprehensible": false
}
8.2.1. UTCWindow
A UTCWindow object describes a time range in UTC or UTC and a zone
offset that can be applied by a TimePolicy.
It is encoded as a JSON object containing the following name/value
pairs:
Name: start
Description: The start time of the window.
Value: Internet date and time as defined in [RFC3339].
Mandatory: No. but at least one of "start" or "end" MUST be
present and non-empty.
Name: end
Description: The end time of the window.
Value: Internet date and time as defined in [RFC3339].
Mandatory: No. but at least one of "start" or "end" MUST be
present and non-empty.
Example JSON serialized UTCWindow object that describes a time window
from 02:30 01/01/2000 UTC to 04:30 01/01/2000 UTC:
{
"start": "2000-01-01T02:30:00.00Z",
"end": "2000-01-01T04:30:00.00Z"
}
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Example JSON serialized UTCWindow object that describes a time window
in New York time zone offset UTC-05:00 from 02:30 01/01/2000 to 04:30
01/01/2000:
{
"start": "2000-01-01T02:30:00.00-05:00",
"end": "2000-01-01T04:30:00.00-05:00"
}
8.3. ExecutionPolicy Extension
Unless specified otherwise, dCDN is at liberty to decide how to
choose trigger commands for execution from all pending commands,
whether to process trigger commands sequentially or in parallel,
immediately upon acceptance, or with a delay in batches. uCDN may
wish to control trigger processing in more detail, including the
order of execution, dependencies, and concurrency.
Example use cases:
* Priority: uCDN may have multiple trigger commands in "pending"
and/or "active" mode. For example, trigger commands with policy
constraints, a large number of content objects affected, or other
dCDN business logic may take a long time to execute. uCDN may
wish to prescribe the order in which dCDN picks up its trigger
commands for execution from the "pending" queue, by indicating a
relative priority of each trigger. The priority would affect the
selection of trigger commands specific to the requesting uCDN.
dCDN may separately prioritize triggers from multiple uCDNs
subject to its business logic. Multiple priority-related use
cases exist:
- uCDN needs to introduce an urgent "purge" or "invalidate"
trigger into an existing queue of trigger commands to correct
wrong versions of content objects published by it
- uCDN needs to indicate which content objects should be
prepositioned, purged or invalidated first, for example
prepositioning newer released content before prepositioning
updates to an existing catalog
* Pre-requisite: In some cases, uCDN may wish to indicate what
trigger commands should be processed and completed before another
trigger command is processed. For example, uCDN may want to
rectify incorrectly published content by purging content objects
and then prepositioning them again. In this case, uCDN may want
the preposition trigger command to be processed only after the
purge trigger command has been processed because concurrent
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processing of these triggers may cause the new version of these
content objects to be purged. Alternatively, uCDN may wish to
condition the execution of purge or invalidation triggers upon the
completion or cancellation of long-running preposition triggers to
avoid race conditions that would result from processing these in
parallel. The prerequisite requirement implies that a previous
trigger reaches one of the following states:
- "complete" or "processed" for successful completion
- "failed" for failed processing
- "cancelled" for completion of cancellation
* Urgency: uCDN may wish to indicate that dCDN should process a
trigger command without delay. This requirement is separate and
additional to priority, as priority indicates the order in which
triggers should be processed, yet does not prescribe how soon each
trigger should be executed. dCDN MAY reject such requests for
urgent processing using "ereject" error code. This can happen due
to dCDN internal business logic (e.g. batch-driven purge and
invalidation), or due to dependencies on other triggers that could
not be completed by dCDN immediately. In such a case uCDN should
either modify the request by removing prerequisites or cancel such
pending triggers before re-trying the request.
uCDN may combine multiple options in the same trigger command. dCDN
should consider the following when processing such commands:
* dCDN MUST reject triggers that are dependent on other pending
triggers with lower priority to prevent deadlocks.
* When introducing an urgent trigger uCDN SHOULD indicate a priority
that is equal to or higher than the highest priority among the
pending triggers that belong to the same uCDN. dCDN MUST reject
urgent triggers that have lower priority than other pending
triggers of the same uCDN.
* dCDN MUST reject an urgent trigger that has pending triggers as
its prerequisite. dCDN MAY reject an urgent trigger that has
triggers in an "active" or "cancelling" state as its prerequisite,
such as when such triggers are deemed to take a long time to
complete or cancel.
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When combining ExtensionPolicy with Section 8.2, TimePolicy governs
the time window when the trigger can execute, while ExecutionPolicy
controls the order of trigger execution within their respective
windows. The following error conditions should be considered by
dCDN:
* When a trigger is marked urgent, but its TimePolicy extension
doesn't allow immediate processing, it should be rejected by dCDN.
* When a trigger has a TimePolicy extension and is also dependent on
another trigger with a TimePolicy extension, that specifies an
execution window (directly or via a chain of dependency) that
doesn't start until after the depending trigger's execution window
ends, such a trigger should be rejected.
The ExtensionPolicy extension is encoded as a JSON object containing
the following name/value pairs:
Name: priority
Description: Relative weight of the trigger. When picking a
trigger for execution from all pending triggers posted by each
uCDN, dCDN MUST choose the trigger with the highest priority
first.
Value: Integer from -100 to 100.
Mandatory: No. The value defaults to zero if omitted.
Name: depends
Description: Links to Trigger Status Resources that the current
Trigger Command depends on. Indicates which triggers should
fully finish processing before starting execution of the
current trigger. The triggers need to be in one of the
following states to be considered finished: "complete",
"processed", "failed" or "cancelled".
Value: A JSON array of zero or more URLs, represented as JSON
strings.
Mandatory: No. In case of a missing or an empty list, no
dependencies are assumed.
Name: urgent
Description: Indicates whether the trigger should be
immediately moved to the "active" state upon acceptance. In
the absence of this flag, dCDN is at liberty to choose the time
for trigger execution, e.g., batch processing.
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Value: Boolean.
Mandatory: No. The default is to handle the Trigger Command as
not urgent.
The following is an example of a JSON serialized generic extension
trigger object containing an execution policy object that specifies
trigger priority of 100, marks Trigger Command as urgent and makes
the Trigger Command execution dependent on the completion of the
previous Trigger Commands:
{
"generic-trigger-extension-type": "execution-policy",
"generic-trigger-extension-value":
{
"priority": 100,
"depends": {
"https://dcdn.com/triggers/100",
"https://dcdn.com/triggers/101"
},
"urgent": true
}
}
9. Footprint and Capabilities
This section covers the FCI objects required for the advertisement of
the specs, extensions, and properties introduced in this document.
9.1. CI/T Endpoint Capability Object
The CI/T trigger endpoint capability object is used to advertise one
or more CI/T interface endpoints along with CI/T interface versions
supported by these endpoints. The capability type is
"FCI.CITEndpoints". Version 1, as originally defined in [RFC8007],
is the default if this capability is not explicitly declared.
A CI/T Endpoints capability object is encoded as an array of JSON
objects containing the following name/value pairs:
Name: trigger-endpoint-uri
Description: CI/T endpoint URI
Value: A URL represented as a JSON string.
Mandatory: Yes.
Name: trigger-versions
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Description: A list of CI/T versions supported by the trigger
endpoint.
Value: An array of JSON strings.
Mandatory: Yes.
Name: trigger-subject
Description: Array of trigger subjects supported by the trigger
endpoint.
Value: An array of Strings containing the type of the subject
matching the generic-trigger-spec-value property, such as
"content" or "metadata" as defined in Section 3.2.1.
Mandatory: No. A missing or empty "trigger-subject" list means
that all trigger subjects are supported by the endpoint. dCDN
SHOULD advertise only one endpoint for every trigger subject
and CI/T interface version pair. If more than one interface
endpoint supports the same trigger subject and CI/T interface
version (e.g. CI/T version 2 interface for content objects),
uCDN SHOULD be able to use any of the advertised CI/T interface
endpoints interchangeably.
9.1.1. CI/T Endpoints Capability Object Serialization
The following shows an example of CI/T Endpoints Capability object
serialization for dCDN that supports versions 2 and 2.1 of the CI/T
interface.
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{
"capabilities": [
{
"capability-type": "FCI.CITEndpoints",
"capability-value": {
"trigger-endpoint-uri":
"https://dcdn.example.com/configuration/",
"trigger-versions": [ "1" ],
"trigger-subjects": "metadata"
},
"footprints": [ <Footprint objects> ]
},
{
"capability-type": "FCI.CITEndpoints",
"capability-value": {
"trigger-endpoint-uri":
"https://dcdn.example.com/cache-management/",
"trigger-versions": [ "2", "2.1" ],
"trigger-subjects": "content"
},
"footprints": [ <Footprint objects> ]
}
]
}
9.2. CI/T Trigger Scope Capability Object
The CI/T supports several trigger actions for different trigger
subjects as defined in Section 3.1 and Section 3.2.1. Additional
actions, as well as subjects, may be defined in the future. The
Trigger Scope capability object is used to indicate support for a
Trigger Action for a subject. It further specifies the Trigger
Generic Spec types that may be used for selecting the targets the
triggers are applied on, along with the supported Trigger Generic
Extension types.
The "trigger-scope-capability" object matches the "FCI.CITScope"
capability type and is encoded as a JSON object containing the
following name/value pairs:
Name: trigger-action
Description: The supported CDNI CI/T Trigger Action.
Value: A string corresponding to an entry from the "CDNI CI/T
Trigger Types" registry Section 11.2, which corresponds to a
CDNI CI/T Trigger Action.
Mandatory: Yes.
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Name: trigger-subject
Description: The supported CDNI CI/T Trigger Subject.
Value: A string corresponding to an entry from the "CDNI CI/T
Trigger Subjects" registry Section 11.4, which corresponds to a
CDNI CI/T Trigger Subject.
Mandatory: Yes.
Name: trigger-specs
Description: A list of supported CDNI CI/T GenericSpecObject
types for Trigger Action and Subject.
Value: List of strings corresponding to entries from the "CDNI
CI/T Trigger Specs" registry Section 11.3, which corresponds to
a CDNI CI/T GenericSpecObject objects.
Mandatory: No. The default, in case of a missing or an empty
list, MUST be interpreted as "no GenericExtensionObject types
are supported". A non-empty list MUST be interpreted as
containing "the only GenericExtensionObject types that are
supported".
Name: trigger-extensions
Description: A list of supported CDNI CI/T
GenericExtensionObject types for Trigger Action and Subject.
Value: List of strings corresponding to entries from the "CDNI
CI/T Trigger Extension" registry Section 11.6, which
corresponds to a CDNI CI/T GenericExtensionObject object.
Mandatory: No. The default, in case of a missing or an empty
list, MUST be interpreted as "no GenericExtensionObject types
are supported". A non-empty list MUST be interpreted as
containing "the only GenericExtensionObject types that are
supported".
9.2.1. CI/T Trigger Scope Capability Object Serialization
The following shows an example of a JSON serialized CI/T Trigger
Scope Capability object serialization for dCDN that supports the
preposition and invalidation of content, using "urls" and "ccids"
Generic Spec types, with "time-policy" but only for the "preposition"
action. Note that in this example, purge is not supported, and no
actions involving metadata are supported either.
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{
"capabilities": [
{
"capability-type": "FCI.CITScope",
"capability-value": {
"trigger-scope-capabilities": [
{
"trigger-action": "preposition",
"trigger-subject": "content",
"trigger-specs": ["urls", "ccids"],
"trigger-extensions": ["time-policy"]
},
{
"trigger-action": "invalidate",
"trigger-subject": "content",
"trigger-specs": ["urls", "ccids"]
}
]
},
"footprints": [
<Footprint objects>
]
}
]
}
9.3. CI/T Object List Type Capability Object
Given an object list being supported by dCDN, the CI/T Object List
Type capability object is used to indicate support for one or more
Object List types listed in Section 11.5 by the type property of the
"ObjectList" object. The capability type is "FCI.CITObjectListType".
Name: object-list-types
Description: A list of supported ObjectList types.
Value: An array of Section 6.2.9.1.
Mandatory: No. In case of a missing or an empty list, MUST be
interpreted as no ObjectList types are supported.
9.3.1. CI/T Object List Type Capability Object Serialization
The following shows an example of a JSON serialized CI/T Object List
Type Capability object serialization for dCDN that supports "hls" and
"dash".
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{
"capabilities": [
{
"capability-type": "FCI.CITObjectListType",
"capability-value": {
"object-list-types": ["hls", "dash", "json"]
},
"footprints": [ <Footprint objects> ]
}
]
}
9.4. CI/T Private URL Capability Object
The CI/T Private URL capability object is used to indicate support
for operations on private URLs (see Section 6.2.8 for details). The
capability type is "FCI.CITPrivateUrlType".
Name: private-url-type-support
Description: Indicate whether private URL type is supported by
dCDN.
Value: Boolean.
Mandatory: No. In case of missing or an empty attribtue, MUST
be interpreted as no support for private URLs.
9.4.1. CI/T Private URL Type Capability Object Serialization
The following shows an example of a JSON serialized CI/T Private URL
Type Capability object serialization for dCDN that supports the
private URL type in URL-based trigger spec types.
{
"capabilities": [
{
"capability-type": "FCI.CITPrivateUrlType",
"capability-value": {
"private-url-type-support": true
},
"footprints": [ <Footprint objects> ]
}
]
}
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9.5. CI/T Extended Status Capability Object
CI/T Extended Trigger Status Capability object is used to indicate
support for extended trigger status. The extended trigger status is
returned upon uCDN request and includes:
* "objects" attribute in Trigger Status object
* "objects" attribute in Error.v2 Description object
* "all-triggers" attribute in Trigger Collections object
The capability type is "FCI.CITExtendedStatus".
Name: extended-status-objects
Description: List of CI/T objects that support extended
attributes.
Value: An array of JSON strings listing CI/T objects.
Mandatory: No. By default, in case of a missing or an empty
list, no extended attribute objects are supported.
9.5.1. CI/T Private URL Type Capability Object Serialization
The following shows an example of a JSON serialized CI/T Extended
Status Type Capability object serialization for dCDN that supports
extended status in Trigger Status, Error.v2 Description and Trigger
Collections objects.
{
"capabilities": [
{
"capability-type": "FCI.CITExtendedStatus",
"capability-value": {
"extended-status-objects": [
"trigger-status",
"error-v2-description",
"trigger-collection"
]
},
"footprints": [ <Footprint objects> ]
}
]
}
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10. Examples
The following subsections provide examples of different CI/T objects
encoded as JSON.
The discovery of the CI/T interface is out of scope of this document.
In an implementation, all CI/T URLs are under the control of the
dCDN. uCDN MUST NOT attempt to ascribe any meaning to individual
elements of the path.
In examples in this section, the URL "https://dcdn.example.com/
triggers" is used as the location of the collection of all Trigger
Status Resources, and the CDN PID of uCDN is "AS64496:1".
10.1. Creating Triggers
Examples of uCDN triggering activity in dCDN:
10.1.1. Preposition
Below is an example of a CI/T "preposition" command -- a POST to the
collection of all Trigger Status Resources.
Note that pattern-based specs like "UriPatternMatch" and
"UrisRegexMatch" are not allowed in a pre-position Trigger
Specification, where dCDN has to have a clear list of objects to
obtain.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.create.v2
Content-Length: 352
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
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}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
],
},
"cdn-path": [ "AS64496:1" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://dcdn.example.com/triggers/0
Server: example-server/0.1
{
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "pending",
"trigger": {
"action": "preposition"
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
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"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
]
}
}
10.1.2. Invalidate
Below is an example of a CI/T "invalidate" command -- another POST to
the collection of all Trigger Status Resources. This instructs the
dCDN to revalidate the content at "https://www.example.com/a/
index.html", as well as any metadata and content whose URLs are
prefixed by "https://metadata.example.com/a/b/" using case-
insensitive matching, and "https://www.example.com/a/b/" using case-
sensitive matching, respectively.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.create.v2
Content-Length: 387
{
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
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"https://www.example.com/a/index.html"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
},
"cdn-path": [ "AS64496:1" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Length: 545
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://dcdn.example.com/triggers/1
Server: example-server/0.1
{
"ctime": 1462351691,
"etime": 1462351699,
"mtime": 1462351691,
"status": "pending",
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/index.html"
]
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}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
}
}
10.1.3. Invalidation with Regex
In the following example, a CI/T "invalidate" command uses the Regex
property to specify the range of content objects for invalidation,
the command is rejected by dCDN due to regex complexity, and an
appropriate error is reflected in the status response.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.create.v2
{
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-regex-match",
"generic-trigger-spec-value": {
"regex": "^(https:\\/\\/video\\.example\\.com)\\/
([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
}
]
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
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HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/2
Server: example-server/0.1
{
"errors": [
{
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-regex-match",
"generic-trigger-spec-value": {
"regex": "^(https:\\/\\/video\\.example\\.com)\\/
([a-z])\\/movie1\\/
([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
}
],
"description": "dCDN rejected a regex due to complexity",
"error": "ereject",
"cdn": "AS64500:0"
}
],
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
10.1.4. Preposition with ObjectLists
In the following example, a CI/T "preposition" command uses the
ObjectList property to specify the full media library of a specific
content. The command fails due to object list parse error and an
appropriate error is reflected in the status response.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
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Content-Type: application/cdni; ptype=ci-trigger-command.create.v2
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "content-objectlist",
"generic-trigger-spec-value": {
"href":
"https://www.example.com/hls/title/index.m3u8",
"type": "hls"
}
}
]
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/3
Server: example-server/0.1
{
"errors": [
{
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "content-objectlist",
"generic-trigger-spec-value": {
"href":
"https://www.example.com/hls/title/index.m3u8",
"type": "hls"
}
}
],
"description":
"dCDN was not able to parse the object list",
"error": "econtent",
"cdn": "AS64500:0"
}
],
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"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
10.2. Examining Trigger Status
Once Trigger Status Resources have been created, uCDN can check their
status as shown in the following examples.
10.2.1. Collection of All Triggers
uCDN can fetch the collection of all Trigger Status Resources it has
created that have not yet been deleted, removed or expired. After
the creation of the "preposition" and "invalidate" triggers shown
above, this collection might look as follows:
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REQUEST:
GET /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 341
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "-936094426920308378"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"cdn-id": "AS64496:0",
"coll-status": [
{ "status": "pending", "collection": "/triggers/pending" },
{ "status": "active", "collection": "/triggers/active" },
{ "status": "complete", "collection": "/triggers/complete" },
{ "status": "processed", "collection": "/triggers/processed" },
{ "status": "failed", "collection": "/triggers/failed" },
{ "status": "cancelling",
"collection":"/triggers/cancelling" },
{ "status": "cancelled", "collection": "/triggers/cancelled" }
],
"coll-label": [
{ "label": "1b1bad0c", "collection": "/triggers/1b1bad0c" },
{ "label": "fafa9a97", "collection": "/triggers/fafa9a97" }
],
"staleresourcetime": 86400,
triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
10.2.2. Filtered Collections of Trigger Status Resources
The filtered collections are also available to uCDN. Before the dCDN
starts processing the two CI/T Trigger Commands shown above, both
will appear in the collection of pending triggers. For example:
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REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 152
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "4331492443626270781"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
At this point, if no other Trigger Status Resources had been created,
the other filtered views would be empty. For example:
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REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 54
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "7958041393922269003"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": []
}
10.2.3. Individual Trigger Status Resources
The Trigger Status Resources can also be examined for details about
individual CI/T Trigger Commands. For example, for the CI/T
"preposition" and "invalidate" commands from previous examples:
REQUEST:
GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 467
Expires: Wed, 04 May 2016 08:49:10 GMT
Server: example-server/0.1
ETag: "6990548174277557683"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Type: application/cdni; ptype=ci-trigger-status.v2
{
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"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "pending",
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
]
}
}
REQUEST:
GET /triggers/1 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 545
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "-554385204989405469"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
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Content-Type: application/cdni; ptype=ci-trigger-status.v2
{
"ctime": 1462351691,
"etime": 1462351699,
"mtime": 1462351691,
"status": "pending",
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/index.html"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
}
}
10.2.4. Polling for Changes in Status
uCDN SHOULD use the ETags of collections or Trigger Status Resources
when polling for changes in status, as shown in the following
examples:
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REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "4331492443626270781"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "4331492443626270781"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
REQUEST:
GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "6990548174277557683"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 04 May 2016 08:49:10 GMT
Server: example-server/0.1
ETag: "6990548174277557683"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Type: application/cdni; ptype=ci-trigger-status.v2
When the CI/T Trigger Command is complete, the contents of the
filtered collections will be updated along with their ETags. For
example, when the two example CI/T Trigger Commands are complete, the
collections of pending and complete Trigger Status Resources might
look like:
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REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 54
Expires: Wed, 04 May 2016 08:49:15 GMT
Server: example-server/0.1
ETag: "1337503181677633762"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:15 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": []
}
REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 152
Expires: Wed, 04 May 2016 08:49:22 GMT
Server: example-server/0.1
ETag: "4481489539378529796"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
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10.2.5. Deleting Trigger Status Resources
uCDN can delete completed and failed Trigger Status Resources to
reduce the size of the collections, as described in Section 5.5. For
example, to delete the "preposition" request from earlier examples:
REQUEST:
DELETE /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 204 No Content
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Length: 0
Content-Type: text/html; charset=UTF-8
Server: example-server/0.1
This would, for example, cause the collection of completed Trigger
Status Resources shown in the example above, to be updated to:
REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 105
Expires: Wed, 04 May 2016 08:49:22 GMT
Server: example-server/0.1
ETag: "-6938620031669085677"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/1"
]
}
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10.2.6. Extensions with Error Propagation
In the following example, a CI/T "preposition" command is using two
extensions to control the way the trigger is executed. In this
example, the receiving dCDN, identified as "AS64500:0", does not
support the first extension in the extensions array. dCDN "AS64500:0"
further distributes this trigger to another downstream CDN that is
identified as "AS64501:0", which does not support the second
extension in the extensions array. The error is propagated from
"AS64501:0" to "AS64500:0" and the errors.v2 array reflects both
errors.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.create.v2
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "content-objectlist",
"generic-trigger-spec-value": {
"href":
"https://www.example.com/hls/title/index.m3u8",
"type": "hls"
}
}
],
"extensions": [
{
"generic-trigger-extension-type": "location-policy",
"generic-trigger-extension-value": {
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": [
"us"
]
}
]
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},
{
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": [
"ca"
]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
},
{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value": {
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
}
]
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/0
Server: example-server/0.1
{
"errors": [
{
"extensions": [
{
"generic-trigger-extension-type": "location-policy",
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"generic-trigger-extension-value": {
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": [
"us"
]
}
]
},
{
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": [
"ca"
]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
}
],
"description": "unrecognized extension <type>",
"error": "eextension",
"cdn": "AS64500:0"
},
{
"extensions": [
{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value": {
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
}
],
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"description": "unrecognized extension <type>",
"error": "eextension",
"cdn": "AS64501:0"
}
],
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
11. IANA Considerations
11.1. CDNI Payload Type Parameter Registrations
All references to RFC 8007 in the IANA registries should be replaced
with references to this document, apart from references associated
with the following registrations:
+=======================+===============+
| Payload Type | Specification |
+=======================+===============+
| ci-trigger-command | RFC 8007 |
+-----------------------+---------------+
| ci-trigger-status | RFC 8007 |
+-----------------------+---------------+
| ci-trigger-collection | RFC 8007 |
+-----------------------+---------------+
Table 11
The IANA is requested to register the following new Payload Types in
the "CDNI Payload Types" registry defined by [RFC7736], for use with
the "application/cdni" MIME media type.
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+==============================+===============+
| Payload Type | Specification |
+==============================+===============+
| ci-trigger-command.create.v2 | RFCthis |
+------------------------------+---------------+
| ci-trigger-command.modify.v2 | RFCthis |
+------------------------------+---------------+
| ci-trigger-status.v2 | RFCthis |
+------------------------------+---------------+
| FCI.CITObjectsVersion | RFCthis |
+------------------------------+---------------+
| FCI.CITScope | RFCthis |
+------------------------------+---------------+
| FCI.CITObjectListType | RFCthis |
+------------------------------+---------------+
Table 12
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
11.1.1. CDNI ci-trigger-command.create.v2 Payload Type
Purpose: The purpose of this payload type is to distinguish the CI/T
v2 create trigger command object (and any associated capability
advertisement)
Interface: CI/T
Encoding: see Section 6.1.1
11.1.2. CDNI ci-trigger-command.modify.v2 Payload Type
Purpose: The purpose of this payload type is to distinguish the CI/T
v2 modify trigger command object (and any associated capability
advertisement)
Interface: CI/T
Encoding: see Section 6.1.2
11.1.3. CDNI ci-trigger-status.v2 Payload Type
Purpose: The purpose of this payload type is to distinguish version 2
of the CI/T status resource response object (and any associated
capability advertisement)
Interface: CI/T
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Encoding: see Section 6.1.3
11.1.4. CDNI FCI CI/T Payload Types
11.1.4.1. CDNI FCI CI/T Endpoints Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Endpoints objects
Interface: FCI
Encoding: see Section 9.1
11.1.4.2. CDNI FCI CI/T Trigger Scope Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Trigger Scope
Interface: FCI
Encoding: see Section 9.2.1
11.1.4.3. CDNI FCI CI/T Object List Type Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Object List Type objects
Interface: FCI
Encoding: see Section 9.3
11.2. "CDNI CI/T Trigger Types" Registry For Trigger Actions
In [RFC8007] the IANA was requested to create a new "CDNI CI/T
Trigger Types" registry under the "Content Delivery Network
Interconnection (CDNI) Parameters" registry group.
Additions to the "CDNI CI/T Trigger Types" registry are made via the
RFC Required policy as defined in [RFC8126].
In this second edition of the interface, trigger types are referred
to as "trigger actions". The "Trigger Types" registry is used for
action definitions. Furthermore, this document, and specifically
Section 3.1, reuses the definition of "trigger types" as defined in
[RFC8007] as trigger actions, and provide their specifications, with
no modification compared to [RFC8007].
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11.3. "CDNI CI/T Trigger Specs" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Specs"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Specs" namespace
defines the valid trigger targets' spec values in Section 3.2, used
by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Specs" registry are made via the
RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Specs" registry
comprise the names and descriptions listed in Section 3.2, with this
document acting as the specification.
11.4. "CDNI CI/T Trigger Subjects" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Subjects"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Subjects"
namespace defines the valid trigger targets' subject values in
Section 3.2.1, used by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Subjects" registry are made via
the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Subjects" registry
comprise the names and descriptions listed in Section 3.2.1, with
this document acting as the specification.
11.5. "CDNI CI/T Object List Types" Registry
The IANA is requested to create a new "CDNI CI/T Object List Types"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Object List Types"
namespace defines the valid object list type values in
Section 6.2.9.1, used by the Object List object.
Additions to the "CDNI CI/T Object List Types" registry are made via
the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Object List Types" registry
comprise the names and descriptions listed in Section 6.2.9.1, with
this document acting as the specification.
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11.6. "CDNI CI/T Trigger Extensions" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Extensions"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Extensions"
namespace defines the valid trigger targets' extension values in
Section 3.3, used by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Extensions" registry are made via
the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Extensions" registry
comprise the names and descriptions listed in Section 3.3, with this
document acting as the specification.
11.7. "CDNI CI/T Error Codes" Registry
In [RFC8007] the IANA was requested to create a new "CDNI CI/T Error
Codes" registry under the "Content Delivery Network Interconnection
(CDNI) Parameters" registry group.
Additions to the "CDNI CI/T Error Codes" registry are made via the
Specification Required policy as defined in [RFC8126]. The
Designated Expert will verify that new Error Code registrations do
not duplicate existing Error Code definitions (in name or
functionality), prevent gratuitous additions to the namespace, and
prevent any additions to the namespace that would impair the
interoperability of CDNI implementations.
In this second edition of the interface, we list and repeat the
definition of the Error Codes from [RFC8007] - acting as the entities
specification with no modification compared to [RFC8007].
Additionally, the IANA is requested to register three additional
error codes, "espec", "esubject" and "eextension", with specification
as defined in Section 6.2.7.
11.8. "CDNI CI/T URL Types" Registry
The IANA is requested to create a new "CDNI CI/T URL types" registry
in the "Content Delivery Networks Interconnection (CDNI) Parameters"
registry group. The "CDNI CI/T URL Types" namespace defines the
valid URL type values in Section 6.2.8, used by Section 7.1,
Section 7.3, Section 7.4 and Section 7.5.
The initial contents of the "CDNI CI/T Trigger Extensions" registry
comprise the names and descriptions listed in Section 6.2.8, with
this document acting as the specification.
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12. Security Considerations
The CI/T interface provides a mechanism to allow uCDN to generate
requests into dCDN and to inspect its own CI/T requests and their
current states. The CI/T interface does not allow access to, or
modification of, uCDN or dCDN metadata relating to content delivery
or to the content itself. It can only control the presence of that
metadata in dCDN, and the processing work and network utilization
involved in ensuring that presence.
By examining "preposition" requests to dCDN, and correctly
interpreting content and metadata URLs, an attacker could learn the
uCDN's or content owner's predictions for future content popularity.
By examining "invalidate" or "purge" requests, an attacker could
learn about changes in the content owner's catalog.
By injecting CI/T Commands, an attacker or a misbehaving uCDN would
generate work in dCDN and uCDN as they process those requests. So
would a man-in-the-middle attacker modify valid CI/T Commands
generated by uCDN. In both cases, that would decrease dCDN's caching
efficiency by causing it to unnecessarily acquire or reacquire
content metadata and/or content.
dCDN implementation of CI/T MUST restrict the actions of uCDN to the
data corresponding to that uCDN. Failure to do so would allow uCDNs
to detrimentally affect each other's efficiency by generating
unnecessary acquisition or reacquisition load.
An origin that chooses to delegate its delivery to a CDN is trusting
that CDN to deliver content on its behalf; the interconnection of
CDNs is an extension of that trust to dCDNs. That trust relationship
is a commercial arrangement, outside the scope of the CDNI protocols.
So, while a malicious CDN could deliberately generate load on dCDN
using the CI/T interface, the protocol does not otherwise attempt to
address malicious behavior between interconnected CDNs.
12.1. Authentication, Authorization, Confidentiality, Integrity
Protection
A CI/T implementation MUST support Transport Layer Security (TLS)
transport for HTTP (HTTPS) as per [RFC9110].
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TLS MUST be used by the server side (dCDN) and the client side (uCDN)
of the CI/T interface, including the authentication of the remote
end, unless alternate methods are used to ensure the security of the
information in the CI/T interface requests and responses (such as
setting up an IPsec tunnel between the two CDNs or using a physically
secured internal network between two CDNs that are owned by the same
corporate entity).
The use of TLS for transport of the CI/T interface allows dCDN and
uCDN to authenticate each other using the TLS client authentication
and TLS server authentication.
Once dCDN and uCDN have mutually authenticated each other, TLS
allows:
* dCDN and uCDN to authorize each other (to ensure that they are
receiving CI/T Commands from, or reporting status to, an
authorized CDN).
* CDNI commands and responses to be transmitted with
confidentiality.
* Protection of the integrity of CDNI commands and responses.
When TLS is used, the general TLS usage guidance in [RFC9325] MUST be
followed.
The mechanisms for access control are dCDN-specific and are not
standardized as part of this CI/T specification.
HTTP requests that attempt to access or operate on CI/T data
belonging to another CDN MUST be rejected using, for example, HTTP
403 ("Forbidden") or 404 ("Not Found"). This is intended to prevent
unauthorized users from generating unnecessary load in dCDNs or uCDNs
due to revalidation, reacquisition, or unnecessary acquisition.
When deploying a network of interconnected CDNs, the possible
inefficiencies related to the diamond configuration discussed in
Section 2.2.1 should be considered.
12.2. Denial of Service
This document does not define a specific mechanism to protect against
Denial-of-Service (DoS) attacks on the CI/T interface. However, CI/T
endpoints can be protected against DoS attacks through the use of TLS
transport and/or via mechanisms outside the scope of the CI/T
interface, such as firewalling or the use of Virtual Private Networks
(VPNs).
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Depending on the implementation, triggered activity may consume
significant processing and bandwidth in dCDN. A malicious or faulty
uCDN could use this to generate unnecessary load in dCDN. dCDN
should consider mechanisms to avoid overload -- for example, by rate-
limiting acceptance or processing of CI/T Commands, or by performing
batch processing.
12.3. Privacy
The CI/T protocol does not carry any information about individual end
users of a CDN; there are no privacy concerns for end users.
The CI/T protocol does carry information that could be considered
commercially sensitive by CDN operators and content owners. The use
of mutually authenticated TLS to establish a secure session for the
transport of CI/T data, as discussed in Section 12.1, provides
confidentiality while the CI/T data is in transit and prevents
parties other than the authorized dCDN from gaining access to that
data. dCDN MUST ensure that it only exposes CI/T data related to uCDN
to clients it has authenticated as belonging to that uCDN.
13. References
13.1. Normative References
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,
selection, and registration of an Autonomous System (AS)",
BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996,
<https://www.rfc-editor.org/info/rfc1930>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC8006] Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
"Content Delivery Network Interconnection (CDNI)
Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
<https://www.rfc-editor.org/info/rfc8006>.
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[RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network
Interconnection (CDNI) Control Interface / Triggers",
RFC 8007, DOI 10.17487/RFC8007, December 2016,
<https://www.rfc-editor.org/info/rfc8007>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[RFC9112] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
June 2022, <https://www.rfc-editor.org/info/rfc9112>.
[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>.
13.2. Informative References
[ECMA404] ECMA International, "ECMA-404 - The JSON data interchange
syntax", Edition 2, December 2017, <https://ecma-
international.org/publications-and-standards/standards/
ecma-404/>.
[ISO8601] ISO, "Data elements and interchange formats -- Information
interchange -- Representation of dates and times",
ISO 8601:2004, Edition 3, December 2004,
<https://www.iso.org/standard/40874.html>.
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[MPEG-DASH]
ISO, "Information technology -- Dynamic adaptive streaming
over HTTP (DASH) -- Part 1: Media presentation description
and segment format", ISO/IEC 23009-1:2014, Edition 2, May
2014, <https://www.iso.org/standard/65274.html>.
[MSS] Microsoft, "[MS-SSTR]: Smooth Streaming Protocol",
Protocol Revision 8.0, September 2017,
<https://msdn.microsoft.com/en-us/library/ff469518.aspx>.
[POSIX.1] "The Open Group Base Specifications Issue 7", IEEE
Std 1003.1 2018 Edition, 31 January 2018,
<http://pubs.opengroup.org/onlinepubs/9699919799/>.
[REST] Fielding, R.T., "Representational State Transfer (REST)",
Edition 2, December 2017.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, DOI 10.17487/RFC6707, September
2012, <https://www.rfc-editor.org/info/rfc6707>.
[RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
August 2014, <https://www.rfc-editor.org/info/rfc7336>.
[RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
Network Interconnection (CDNI) Requirements", RFC 7337,
DOI 10.17487/RFC7337, August 2014,
<https://www.rfc-editor.org/info/rfc7337>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <https://www.rfc-editor.org/info/rfc7736>.
[RFC7975] Niven-Jenkins, B., Ed. and R. van Brandenburg, Ed.,
"Request Routing Redirection Interface for Content
Delivery Network (CDN) Interconnection", RFC 7975,
DOI 10.17487/RFC7975, October 2016,
<https://www.rfc-editor.org/info/rfc7975>.
[RFC8216] Pantos, R., Ed. and W. May, "HTTP Live Streaming",
RFC 8216, DOI 10.17487/RFC8216, August 2017,
<https://www.rfc-editor.org/info/rfc8216>.
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Acknowledgments
The authors thank Kevin Ma for his input, and Carsten Bormann for his
review and formalization of the JSON data.
Authors' Addresses
Nir B. Sopher
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Email: nir@apache.org
Ori Finkelman
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Email: ori.finkelman.ietf@gmail.com
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
United States of America
Email: sanjay.mishra@verizon.com
Jay K. Robertson
Qwilt
275 Shoreline Dr Ste 510
Redwood City, CA 94065
United States of America
Email: jayrobertson@acm.org
Alan Arolovitch
Viasat
1295 Beacon street Unit 249
Brookline, MA 02446
United States of America
Email: alan.arolovitch@gmail.com
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