Network Working Group T. Iijima
Internet-Draft Y. Atarashi
Intended status: Informational H. Kimura
Expires: April 21, 2008 Alaxala Networks Corp.
K. Toumura
H. Okita
Central Research Laboratory,
Hitachi, Ltd.
October 19, 2007
Experience of implementing NETCONF over SOAP
draft-iijima-netconf-soap-implementation-03
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Abstract
NETCONF protocol is standardized to be exchanged over SSH, SOAP, or
BEEP. We developed a network management system based on NETCONF
protocol. For several reasons, we chose the SOAP protocol as a
transport protocol of NETCONF. This document describes why we chose
SOAP as a transport protocol and the insight gained from actual
development.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. NETCONF over SOAP . . . . . . . . . . . . . . . . . . . . 3
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Framework of Web service . . . . . . . . . . . . . . . . . . . 4
2.1. SOAP as a messaging technology . . . . . . . . . . . . . . 4
2.2. WSDL as an Interface Description Language . . . . . . . . 5
3. Insight from our Implementation . . . . . . . . . . . . . . . 6
3.1. SOAP implementation of the NMS . . . . . . . . . . . . . . 7
3.1.1. Session maintenance in NMS . . . . . . . . . . . . . . 7
3.2. SOAP implementation of network equipment . . . . . . . . . 7
3.2.1. SOAP Engine . . . . . . . . . . . . . . . . . . . . . 8
3.2.2. Session maintenance in network equipment . . . . . . . 8
4. A procedure of development of NETCONF manager and agent . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 15
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1. Introduction
1.1. NETCONF over SOAP
In order to enable network equipment configuration automatically from
network systems, NETCONF is designed to use XML as its description
language since XML is easy for systems to understand. XML is a
suitable technology to cope with flexible specification changes and
frequent functional extensions, and it enables automatic operation.
SOAP is also designed to use XML and is expected to become an
indispensable technology of Web service. For this reason, SOAP is a
prospective technology and well suited to the NETCONF protocol.
1.2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [3].
1.3. Motivation
This document describes why SOAP is practical as a transport protocol
of NETCONF in developing a network management system. This document
also describes the experience of implementing NETCONF over SOAP.
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2. Framework of Web service
SOAP is considered to be an indispensable technology of Web service.
So if we use SOAP as a transport protocol of NETCONF, network
configuration by NETCONF is achieved on a framework of Web service.
In this section, we describe the overall architecture of the Web
service.
+---+ +-----------+ +----------------+ +--------------+ +--------+
| | | Security | |Reliable Message| | Transaction | | Search |
|XML| | | | | | | | |
| | |WS-Security| | WS-Reliability | |WS-Transaction| | UDDI |
| | | | | | | | +--------+
| | | | | | | | +--------+ +---------+
| | | | | | | | |language| | API |
| | | | | | | | | | | |
| | | | | | | | | WSDL | | JAXM |
| | +-----------+ +----------------+ +--------------+ +--------+ | JAX-RPC |
| | +----------------------------------------------------------+ | .NET |
| | | Fundamental Messaging | | |
| | | | | |
| | | SOAP | | |
+---+ +----------------------------------------------------------+ +---------+
+----------------------------------------------------------+
| Transport |
| |
| HTTP, HTTPS... |
+----------------------------------------------------------+
Figure 1: Overall architecture of Web service
As depicted in figure 1, peripheral technologies around SOAP/HTTP are
well developed, including security technology. For instance, WS-
Security and WS-Transaction technology are installed on SOAP only by
inserting particular messages in the SOAP Header. If we do not
choose SOAP/HTTP as a transport layer of the NETCONF protocol, we
have to develop each surrounding technology from scratch. Hence,
when introducing additional technologies around SOAP, the development
of a NETCONF-based network management system is relatively easy when
we choose SOAP as a transport protocol of NETCONF.
2.1. SOAP as a messaging technology
SOAP is basically designed to use distributed objects scattered
around the Internet regardless of platform. Therefore, SOAP is
developed as a messaging technology that uses standardized internet
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technology such as HTTP and XML.
In addition, SOAP is so flexible that it is easy to incorporate other
technologies. For instance, the notion of session can be easily
incorporated in SOAP by inserting a message ID into a SOAP Header.
2.2. WSDL as an Interface Description Language
WSDL is designed so as to bind easily with SOAP. WSDL is an
innovative technology for Web service since the development tool
automatically generates interfaces to Web service by simply importing
WSDL into the development tool. Developers only need to customize
the programs by putting the generated interfaces together.
Regarding development tools that understand WSDL, useful technologies
are available with SOAP. For instance, Apache Axis is an interface
generator from WSDL as well as a widely used SOAP implementation. If
we choose SOAP as a transport protocol, we do not need to develop
interfaces to Web service by ourselves owing to the development tool.
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3. Insight from our Implementation
In this section, we describe the architecture of NETCONF
implementation using SOAP as its transport protocol. Figure 2 is the
architecture of the NETCONF implementation using SOAP. SOAP
implementation is implemented on both a network management system and
network equipment. And each SOAP implementation exchanges SOAP
messages based on the WSDL which is provided by [2]. If Java library
which is generated from the WSDL are provided on the network
management system, engineers can develop NETCONF application, which
can configure network equipment via the NETCONF protocol. NETCONF
application works as a NETCONF manager and network equipment works as
a NETCONF agent.
+-------------------------------------------------------+
| Network Management System |
| |
| +--------------------------------------------+ |
| | NETCONF application | |
| +--------------------------------------------+ |
| +--------------------------------------------+ |
| | Java library | |
| +--------------------------------------------+ |
| +--------------------------------------------+ |
| | SOAP Implementation | |
| | | |
| | Apache Axis | |
| +--------------------------------------------+ |
+---------------------|----------^----------------------+
| |
rpc-request | | rpc-reply
/ SOAP | | / SOAP
/ HTTP(S) | | / HTTP(S)
| |
+---------------------v----------|----------------------+
| +--------------------------------------------+ |
| | SOAP Implementation | |
| +--------------------------------------------+ |
| |
| Network Equipment |
+-------------------------------------------------------+
Figure 2: Architecture of NETCONF implementation using SOAP
In the following section, we explain the SOAP implementation in
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detail in both a network management system and network equipment.
3.1. SOAP implementation of the NMS
Several SOAP implementations capable of being installed on NMS
(network management system) are available today. For instance,
Apache Axis is a practical free software implementation of SOAP when
we choose SOAP as a transport protocol. Rapid parsing in the NMS is
achieved by Axis since it uses SAX as its parser.
Also, Axis is not only a SOAP implementation but a useful tool to
develop a NMS. For instance, WSDL2Java, one of Axis's tools, can
generate Java's class file from WSDL file which is provided from
another vendor. Another tool called Java2WSDL does the opposite. We
can generate WSDL file from Java's class file. After we develop a
Java library that can configure network equipment, the interface to
network equipment can be opened to the public in a form of WSDL.
Conclusively, various kinds of benefits can be acquired if we
introduce Axis as a SOAP implementation.
In order to develop NETCONF-capable applications, Java library, which
is generated by Apache Axis tool and run over SOAP implementation,
has to incorporate such functions as management of sessions,
validation of XML messages, and releasing of log messages. By
utilizing these Java library, engineers can easily develop NETCONF
applications.
3.1.1. Session maintenance in NMS
In order to enable session maintenance between NMS and network
equipment, we used cookie field in a HTTP header as a session
identifier. After NMS sends a hello message to network equipment,
NMS receives a newly allocated session identifier which is written in
the cookie field of a replying hello message. For the following SOAP
messages exchange, NMS preserves the cookie paired with the network
equipment's MAC address and uses the it as a session identifier after
that. The store cookie is erased when the NMS sends a close session
message and received a response message from network equipment.
3.2. SOAP implementation of network equipment
SOAP must also be implemented in the network equipment in order to
accept SOAP messages sent from the NMS. Like the case of NMS, some
free SOAP implementations to be installed on network equipment are
available today. However, in the case of network equipment, memory
capacity might be limited. Therefore a memory saving method might be
required when we implement SOAP in the network equipment.
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3.2.1. SOAP Engine
The SOAP message consists of protocol header such as HTTP header and
a SOAP Envelope. The SOAP Envelope is necessary in every SOAP
message. But in regard to the SOAP encodingStyle attribute inside
the Envelope elements, it is not required to be there even though it
is encouraged. So if there's a memory constraint, we can omit a
module of parsing encodingStyle. In that case, default encodingStyle
of "http://schema.xmlsoap.org/soap/encoding" is applied.
Inside of the SOAP Envelope, there are SOAP Header and SOAP Body.
However, the SOAP Header is defined as optional. So, when memory
capacity in network equipment is insufficient, the module that
processes SOAP Header can be omitted. After all, a SOAP engine in
network equipment is allowed to have only a SOAP Envelope and Body
parser.
3.2.2. Session maintenance in network equipment
In order to maintain sessions with the NMS, SOAP implementation in
network equipment must provide session identifier to the NMS. SOAP
implementation in network equipment sets session identifier paired
with network equipment's MAC address in a cookie field of the HTTP
header and sends it as a response message to initial hello message
sent from the NMS. The session identifier is used when locking the
configuration of the network equipment. When network equipment
receives a close message from the NMS, the network equipment erases
the cookie identifier.
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4. A procedure of development of NETCONF manager and agent
TBD
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5. Security Considerations
Security should be considered from two angles. One is transport-
level security, and the other is message-level security. Transport-
level security, such as encryption of entire messages, is a matter of
SSL/TLS. However, message-level security, such as partial encryption
of messages or signatures, should be done by using other
technologies. To fulfill that need, WS-security has been defined.
WS-Security is a Web service technology and is dependent on SOAP
technology. WS-Security technology can be incorporated by inserting
XML encryption and XML signatures into the SOAP Header.
Also, WS-Reliability achieves confirmation of sent messages and
resending of messages. WS-Reliability is also achieved by inserting
particular messages into the SOAP Header.
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6. IANA Considerations
This document has no actions for IANA.
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7. References
7.1. Normative References
[1] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
[2] Goddard, T., "Using NETCONF over the Simple Object Access
Protocol (SOAP)", RFC 4743, December 2006.
7.2. Informative References
[3] Bradner, S. , "Key words for use in RFCs to Indicate
Requirement Levels" , BCP 14 , RFC 2119 , March 1997 .
[4] Sperberg-McQueen, C. , Bray, T. , and J. Paoli , "XML 1.0
Recommendation" , World Wide Web Consortium FirstEdition REC-
xml-19980210 , February 1998 ,
<http://www.w3.org/TR/1998/REC-xml-19980210> .
[5] "Web Services - Axis" .
<http://ws.apache.org/axis/>
[6] "Web Service Description Language (WSDL) 1.1".
<http://www.w3.org/TR/wsdl/>
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Authors' Addresses
Iijima Tomoyuki
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan
Phone: +81-44-549-1200
Fax: +81-44-549-1272
Email: atarashi@alaxala.net
Yoshifumi Atarashi
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan
Phone: +81-44-549-1200
Fax: +81-44-549-1272
Email: atarashi@alaxala.net
Hiroyasu Kimura
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan
Phone: +81-44-549-1200
Fax: +81-44-549-1272
Email: h-kimura@alaxala.net
Toumura Kunihiko
Central Research Laboratory, Hitachi, Ltd.
1-280 Higashi-Koigakubo
Kokubunji, Tokyo 185-8601
Japan
Phone: +81-42-323-1111
Fax: +81-42-327-7868
Email: kunihiko.toumura.yv@hitachi.com
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Hideki Okita
Central Research Laboratory, Hitachi, Ltd.
1-280 Higashi-Koigakubo
Kokubunji, Tokyo 185-8601
Japan
Phone: +81-42-323-1111
Fax: +81-42-327-7868
Email: hideki.okita.pf@hitachi.com
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