Network Working Group T. Iijima

Network Working Group T. Iijima
Request for Comments: 5381 Y. Atarashi
Category: Informational H. Kimura
M. Kitani
Alaxala Networks Corp.
H. Okita
Hitachi, Ltd.
October 2008

Experience of Implementing NETCONF over SOAP

Status of This Memo

This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.

IESG Note

This document discusses implementation experience of NETCONF over
SOAP. Note that Section 2.4 of RFC 4741 states, "A NETCONF
implementation MUST support the SSH transport protocol mapping".
Therefore, a NETCONF implementation that only supports the SOAP
transport described in this document and not (at least) also SSH is
not in compliance with the NETCONF standards.

Abstract

This document describes how the authors developed a SOAP (Simple
Object Access Protocol)-based NETCONF (Network Configuration
Protocol) client and server. It describes an alternative SOAP
binding for NETCONF that does not interoperate with an RFC 4743
conformant implementation making use of cookies on top of the
persistent transport connections of HTTP. When SOAP is used as a
transport protocol for NETCONF, various kinds of development tools
are available. By making full use of these tools, developers can
significantly reduce their workload. The authors developed an NMS
(Network Management System) and network equipment that can deal with
NETCONF messages sent over SOAP. This document aims to provide
NETCONF development guidelines gained from the experience of
implementing a SOAP-based NETCONF client and server.

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Table of Contents

1. Introduction ....................................................3
1.1. NETCONF over SOAP ..........................................3
1.2. Motivation .................................................3
2. NETCONF Development on Web Services Framework ...................4
2.1. WSDL as an Interface Description Language ..................5
2.2. Generation of APIs .........................................5
3. Architecture of the NETCONF over SOAP Implementation ............5
3.1. SOAP Implementation in NMS .................................6
3.1.1. SOAP Parser in NMS ..................................7
3.1.2. Session Maintenance in NMS ..........................7
3.2. SOAP Implementation in the Network Equipment ...............8
3.2.1. SOAP Parser in the Network Equipment ................8
3.2.2. Session Maintenance in the Network Equipment ........8
4. Guidelines for Developing NETCONF Clients and Servers ...........8
4.1. Procedures of Development of NETCONF Clients ...............9
4.1.1. Developing NETCONF Clients without Eclipse .........10
4.1.2. Developing NETCONF Clients Using Eclipse ...........11
4.2. Procedures of Development of NETCONF Servers ..............13
4.2.1. Developing NETCONF Servers without Eclipse .........14
4.2.2. Developing NETCONF Servers Using Eclipse ...........15
4.2.3. Developing NETCONF Servers with C
Programming Language ...............................18
5. Security Considerations ........................................18
6. Acknowledgements ...............................................18
7. References .....................................................19
7.1. Normative References ......................................19
7.2. Informative References ....................................19

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1. Introduction

1.1. NETCONF over SOAP

This document is not a product from the NETCONF WG but a report on
the experience acquired by individual developers.

SOAP (Simple Object Access Protocol) was specified in [RFC4743] as
one of the transport protocols for NETCONF. It is designed to use
XML (eXtensible Markup Language) as its description language, which
is a fundamental messaging technology for Web Services. For this
reason, SOAP is well suited to the NETCONF protocol and can be
deployed widely.

To develop a SOAP-based NETCONF client and server, several
development tools are available as open-source software. The authors
developed a SOAP-based NETCONF client and server by using available
development tools. The SOAP-based NETCONF client was developed by
utilizing Java APIs (Application Programming Interfaces) that are
automatically generated from the XSD (XML Schema Definition) file and
WSDL (Web Services Description Language) file obtained from [RFC4741]
and [RFC4743], respectively. The SOAP-based NETCONF client that the
authors developed acts as an NMS (Network Management System). The
SOAP-based NETCONF server that the authors developed runs on network
equipment and accepts NETCONF messages sent from the NETCONF client.

1.2. Motivation

The aim of this document is to describe why the authors believe SOAP
is practical as a transport protocol for NETCONF when an NMS is
developed. When developing an NMS that uses SOAP as its transport
protocol, development tools and procedures can be used according to
the Web Services framework. This document also describes the
experience of implementing NETCONF over SOAP so that even those who
have little knowledge of SOAP can start developing a SOAP-based
NETCONF client and server.

This document describes an alternative SOAP binding for NETCONF that
does not interoperate with an RFC 4743 conformant implementation as
it relies on cookies used on top of the persistent transport
connections of HTTP. This is provided for information purposes only
based on the implementation experience of the authors.

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2. NETCONF Development on Web Services Framework

SOAP is a fundamental messaging technology for Web Services.
Therefore, if SOAP is used as a transport protocol for NETCONF, a
network configuration performed by NETCONF is achieved on the Web
Services framework. In this section, the overall architecture of Web
Services is described.

+----------------+ +----------------------------+
| Format | | Register / Search |
| | | |
| XML | | UDDI |
| | | (Universal Description, |
| | | Discovery and Integration) |
| | +----------------------------+
| | +----------------------------+ +----------------+
| | | Service Description | | API |
| | | | | |
| | | WSDL | | JAXM |
| | +----------------------------+ | (Java API for |
| | +----------------------------+ | XML Messaging) |
| | | Fundamental Messaging | | JAX-RPC |
| | | | | (Java API for |
| | | SOAP | | XML / RPC) |
+----------------+ +----------------------------+ +----------------+
+----------------------------+
| Transport |
| |
| HTTP, HTTPS... |
+----------------------------+

Figure 1: Overall Architecture of Web Services

As depicted in Figure 1, peripheral technologies around SOAP/HTTP are
well developed. Therefore, if SOAP/HTTP is chosen as a transport
layer for the NETCONF protocol, the NMS development based on the Web
Services framework can choose from different optional services and
might be less expensive based on the use of already available
services.

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2.1. WSDL as an Interface Description Language

WSDL [WSDL] defines how SOAP messages are exchanged between Web
Services entities. Interfaces of Web Services entities are
automatically generated by development tools when importing a WSDL
file. Interfaces generated in this manner act as APIs. For the
development of an NMS, only these APIs are necessary; there is no
need to use SOAP directly.

Useful tools that can import a WSDL file are available with SOAP.
For instance, Apache Axis [Axis] generates an interface from a WSDL
file and is a widely used SOAP implementation middleware.

2.2. Generation of APIs

As described in the previous section, APIs are generated from a WSDL
file by development tools such as Apache Axis. Such APIs are in the
form of a Java library and act as programming interfaces for an NMS.
By using these APIs, an NMS can send SOAP messages to Web Services
entities.

3. Architecture of the NETCONF over SOAP Implementation

The architecture of the NETCONF over SOAP implementation is shown in
Figure 2. A NETCONF implementation residing in an NMS works as a
NETCONF client while network equipment acts as a NETCONF server. In
this document, we call NETCONF-client and NETCONF-server
implementations a NETCONF application and a NETCONF service provider,
respectively. A SOAP implementation may be installed on both the NMS
and the network equipment. Each instance of the SOAP implementations
exchanges SOAP messages based on WSDL, as described in [RFC4743]. If
Java libraries generated from the WSDL are provided in the NMS,
engineers can develop a NETCONF application, which configures network
equipment via the NETCONF protocol, by utilizing the Java library.
There is no need for engineers to use XML or SOAP directly.

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+---------------------------+ +---------------------------+
| NETCONF Client | | NETCONF Server |
| (NMS) | | (Network Equipment) |
| +---------------------+ | | +---------------------+ |
| | NETCONF application | | | | NETCONF service | |
| | | | | | provider | |
| +---------------------+ | | +---------------------+ |
| +---------------------+ | | |
| | Java library | | | |
| +---------------------+ | | |
| +---------------------+ | | +---------------------+ |
| | SOAP Implementation | | | | SOAP Implementation | |
| | (Apache Axis) | | | | | |
| +---------------------+ | | +---------------------+ |
+-------^----------|--------+ +-------^----------|--------+
| | rpc-request | |
| +----- /SOAP ----+ |
| / HTTP(S) |
| |
| rpc-reply |
+---------------- /SOAP ---------------+
/ HTTP(S)
Figure 2: Architecture of NETCONF Implementation Using SOAP

The SOAP implementation in both the NMS and network equipment is
explained in detail in the following sections.

3.1. SOAP Implementation in NMS

Several SOAP implementations appropriate for use in an NMS are
available today. Apache Axis is one such widely used implementation.

Axis works as a SOAP implementation and an NMS-development tool. For
instance, WSDL2Java, one of Axis' tools, generates Java-class files
from a WSDL file. Another tool called Java2WSDL does the opposite:
it generates a WSDL file from Java-class files. Consequently,
various benefits can be obtained if Axis is introduced as a SOAP
implementation.

To develop a NETCONF application that is capable of various functions
such as releasing log messages, Java-class files generated by the
Axis tool may be extended by adding more functions. By utilizing
these Java libraries, engineers can easily develop NETCONF
applications.

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3.1.1. SOAP Parser in NMS

The SOAP Parser function is performed entirely by a SOAP
implementation such as Apache Axis.

3.1.2. Session Maintenance in NMS

When exchanging NETCONF messages between an NMS and network
equipment, a NETCONF session has to be maintained on both sides, as
described in [RFC4741].

In [RFC4743], HTTP is specified as an option of an underlying
protocol for NETCONF over SOAP. When HTTP is used for that purpose,
it is also specified that a NETCONF session state is tied to the
state of the underlying transport (TCP) connection (just like in
NETCONF over SSH [RFC4742] and NETCONF over BEEP [RFC4744]).
However, HTTP itself is a stateless protocol, and many server
implementations process user requests independently of previous
requests received over the same transport connection. To simplify
implementation of the NETCONF service provider, we used the cookie
field inside the HTTP header to map incoming requests to NETCONF
sessions. Note that this means our implementation actually uses an
alternative SOAP binding for NETCONF, which does not interoperate
with RFC 4743 compliant implementations.

For example, the implemented NETCONF-session maintenance in the NMS
works as follows. After the NMS sends a NETCONF hello message to the
network equipment, the NETCONF service provider in the network
equipment allocates a session identifier for the NETCONF application
in the NMS and writes it inside the <session> element of a replying
NETCONF hello message, as described in [RFC4741]. At the same time,
the network equipment writes the same value in the cookie field
inside an HTTP header. After that, a SOAP message encompassing the
replying NETCONF hello message is added. When the NMS receives the
newly allocated session identifier from the replying NETCONF hello
message, the NETCONF application stores it and writes it inside a
<session> element for subsequent NETCONF request messages and in a
cookie field for subsequent HTTP headers. By recognizing the session
identifier in NETCONF request messages and the cookie field in HTTP
headers, the network equipment can maintain both a NETCONF session
and the state of an HTTP connection. The NETCONF session is
maintained over the maintained state of the HTTP connection. The
stored session identifier is erased when the NMS sends a NETCONF
close-session message and receives a NETCONF response message from
the network equipment.

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3.2. SOAP Implementation in the Network Equipment

To accept SOAP messages sent from the NMS, it is also necessary to
provide SOAP in the network equipment. As in the case of NMS, some
free SOAP implementations are available today for installation on
network equipment. However, the memory capacity of the network
equipment might be limited. Therefore, the SOAP implementation may
be chosen taking memory capacity into consideration. In some cases,
a memory-saving method will be required when implementing SOAP in the
network equipment.

3.2.1. SOAP Parser in the Network Equipment

A SOAP header inside the SOAP envelope is defined as optional.
Therefore, the module that processes the SOAP header can be omitted
if the memory capacity in the network equipment is insufficient. In
this case, a SOAP parser in the network equipment is allowed to parse
only mandatory parts of a SOAP envelope.

3.2.2. Session Maintenance in the Network Equipment

To maintain NETCONF sessions with the NMS, the NETCONF service
provider in the network equipment has to provide a session identifier
to the NMS, as described in [RFC4741].

For example, the implemented NETCONF-session maintenance in the
network equipment works as follows. When the network equipment
receives a NETCONF hello message from the NMS, the NETCONF service
provider in the network equipment sets a session identifier inside
the <session> element of a replying NETCONF hello message, as
described in [RFC4741]. At the same time, the network equipment also
sets the same value in the cookie field inside an HTTP header. After
that, a SOAP message encompassing the replying NETCONF hello message
is added. The cookie field inside the HTTP header is used for
maintaining the state of the HTTP connection over which the NETCONF-
session maintenance is ensured. The network equipment then sends an
HTTP response message to the NMS. When the network equipment
receives a NETCONF close-session message from the NMS, it erases the
stored session identifier.

4. Guidelines for Developing NETCONF Clients and Servers

In the case of SOAP transport mapping, sharing information on the
kinds of development tools that are available would help developers
start developing SOAP-based NETCONF clients and servers. That would
contribute to the rapid deployment of SOAP-based NETCONF clients and
servers.

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4.1. Procedures of Development of NETCONF Clients

To develop a SOAP-based NETCONF client, a stub code may be generated.
A stub is a library that is generated automatically from WSDL by a
Web Services tool and that acts as a group of APIs. When using
Apache Axis as a Web Services tool, a generated stub is in the form
of Java APIs. These Java APIs display interfaces of a Web Service as
if they are methods capable of configuring a local machine.

The WSDL file named "netconf-soap_1.0.wsdl", which is selected from
[RFC4743], specifies NETCONF messages to be exchanged between the
NETCONF client and server. These NETCONF messages are the "hello"
message and "rpc" message. Therefore, stub codes for creating the
"hello" message and "rpc" message are generated from "netconf-
soap_1.0.wsdl". However, the file "netconf-soap_1.0.wsdl" is not
sufficient because no service element is specified.

In "myNetconfService.wsdl", which is also selected from [RFC4743], a
service element is specified and "netconf-soap_1.0.wsdl" is imported.
Stub codes generated from those WSDL files are found in files such as
"Netconf.java", "NetconfLocator.java", and "NetconfBindingStub.java".

When interfaces are used to operate the NETCONF protocol in the
manner of "get-config" and "edit-config", for example, an XML schema
file named "netconf.xsd", which is selected from [RFC4741], is used
by being imported into "netconf-soap_1.0.wsdl". Using the XML
schema, methods of operating the NETCONF protocol are generated in
files such as "GetConfigType.java" and "EditConfigType.java".

When interfaces are used to configure network functions at the
network equipment, a data model of each network function has to be
defined in the style of an XML schema. The XML schema may be
imported into "netconf-soap_1.0.wsdl" in the same manner as that of
the XML schema in [RFC4741].

The connection between the NETCONF schema and a data model should be
made by inserting the following attribute into elements of each data
model. This attribute is defined in the XML schema in [RFC4741].

<xs:attribute name="operation" type="editOperationType"
default="merge"/>

Consequently, using "myNetconfService.wsdl" to import "netconf-
soap_1.0.wsdl", NETCONF schema, and the data model makes it possible
to generate stub files containing interfaces to configure network
equipment.

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When stub codes are generated, the development environment may be
arranged as well. The development of a Java-based NETCONF client may
use JDK (Java Development Kit) [JDK] and Apache Axis. In addition,
using some IDE (Integrated Development Environment) such as Eclipse
[Eclipse] with Apache Ant [Ant] and NetBeans [NetBeans] would reduce
the developer workload significantly. When Eclipse is used as an
IDE, first, the library (*.jar files) of Axis has to be added to the
development project's build path as an external library. The library
of Axis acts as a SOAP library, so there is no need to be concerned
about SOAP messaging when programming a NETCONF client using the
library of Axis.

4.1.1. Developing NETCONF Clients without Eclipse

Given that development of a NETCONF client is carried out in the
environment of a Windows computer without Eclipse, and that
"myNetconfService.wsdl" is placed in the "C:\NetconfClient"
directory, a stub is generated by executing the following command in
the command prompt.

C:\NetconfClient>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
\lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
0.2.jar;%AXIS_HOME%\lib\wsdl4j-1.5.1.jar
org.apache.axis.wsdl.WSDL2Java -p stub myNetconfService.wsdl

In the directory where the WSDL file is located, the WSDL2Java
command is executed. Locations of each Axis library have to be
specified. The environment variable of "AXIS_HOME" is the directory
where Axis is installed. By executing the above command, files with
an extension of "*.java" are generated in the "stub" directory, which
is specified by the above command. Inside the stub directory, we can
find files such as "NetconfBindingStub.java", "Hello.java", and
"GetConfigType.java".

Next, it is necessary to compile these files by executing the
following command in the command prompt.

C:\NetconfClient>javac -classpath .;%AXIS_HOME%\lib\axis.jar;%
AXIS_HOME%\lib\jaxrpc.jar stub/*.java

After the compilation of those java files, "*.class" files are
generated. After the compiling is done, the source code of the
NETCONF client has to be written. Sample source code of the NETCONF
client is shown in Figure 3. This NETCONF client is written by
utilizing stub classes and interfaces, which are imported into the
local package and referenced.

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import org.apache.axis.types.UnsignedInt;
import org.apache.axis.types.*;

public class NetconfClient {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try{
NetconfClient client = new NetconfClient();
java.net.URL url = new java.net.URL(args[0]);
stub.Netconf netconf =
new stub.NetconfLocator();
stub.NetconfPortType stubNetconf =
netconf.getnetconfPort(url);

URI[] uri = new URI[1];
stub.holders.HelloCapabilitiesHolder
capability = new
stub.holders.HelloCapabilitiesHolder(uri);

UnsignedInt id = new UnsignedInt();
id.setValue(1);
org.apache.axis.holders.UnsignedIntHolder
holder = new
org.apache.axis.holders.UnsignedIntHolder(id)
;
stubNetconf.hello(capability, holder);
}catch(Exception e){
e.printStackTrace();
}
}
}

Figure 3: Sample Source Code of NETCONF Clients

To add functions such as the release of log messages, these functions
have to be incorporated at this stage. Again, the NETCONF client is
developed by compiling its source codes.

4.1.2. Developing NETCONF Clients Using Eclipse

When we use Eclipse and Apache Ant, the procedures described in the
previous section are significantly simplified and executed at one
time. In this case, files named "build.xml" and "build.properties"
are required for Apache Ant.

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The file named "build.xml" is written in XML and seen by Apache Ant
when Apache Ant is running on Eclipse. The file specifies how Apache
Ant behaves. According to the descriptions of the file, Apache Ant
compiles source codes, generates JAR (Java ARchive) file, and so on.
On the other hand, the file named "build.properties" specifies
properties of the development environment where Apache Ant runs.
This file is referred to by the "build.xml" file.

Examples of "build.xml" and "build.properties" are shown in Figure 4
and Figure 5, respectively.

<?xml version="1.0"?>
<project name="NetconfClient" default="all" basedir=".">
<property file="build.properties"/>
<path id="axis-classpath">
<fileset dir="${axis.libdir}">
<include name="*.jar"/>
</fileset>
</path>
<target name="prepare">
<mkdir dir="${destdir}"/>
</target>
<target name="stub" depends="prepare">
<java classname="org.apache.axis.wsdl.WSDL2Java" fork
="Yes">
<arg value="-o"/>
<arg value="${srcdir}"/>
<arg value="-p"/>
<arg value="${stub.stubdir}"/>
<arg value="${stub.wsdlpath}"/>
<classpath refid="axis-classpath"/>
</java>
</target>
<target name="compile" depends="stub">
<javac srcdir="${srcdir}" destdir="${destdir}"
encoding="UTF-8">
<classpath refid="axis-classpath"/>
</javac>
</target>
<target name="stub-jar" depends="compile">
<jar jarfile="${stub.jar}" basedir="${destdir}"/>
</target>
<target name="all" depends="stub-jar"/>
</project>

Figure 4: build.xml of NETCONF Clients

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axis.libdir=C:/axis-1_4/lib
srcdir=src
destdir=classes
stub.stubdir=stub
stub.wsdlpath=myNetconfService.wsdl
stub.jar=NETCONF.jar

Figure 5: build.properties of NETCONF Clients

The location of the WSDL file should be specified in the
"build.properties" file. In the case shown in Figure 5, the location
of the WSDL file is specified as being under the current directory.

By running Apache Ant on Eclipse, the steps specified in Figure 4 are
taken. First, stub codes are generated. Then, compiling of those
stub codes is executed. We were careful about the encoding style
used for the compiling. After the compilation, Apache Ant will
generate a JAR file, which is the output that compresses all stub
files (*.class) and acts as a library. In this example, the name
"NETCONF.jar" is specified in Figure 5. The "NETCONF.jar" file also
has to be added to the build path of the development project as an
external library.

After the "NETCONF.jar" file is added to the build path of the
development project, source codes of the NETCONF client can be
written by utilizing stub classes and interfaces. Source codes like
the one shown in Figure 3 can be written. By running Apache Ant
again, the source code of the NETCONF client is compiled. The
NETCONF client is developed in this manner.

4.2. Procedures of Development of NETCONF Servers

In the Web Services framework, there are two approaches for
developing a Web Services provider, namely a NETCONF server. One is
called the top-down approach, and the other is called the bottom-up
approach. The top-down approach is carried out by first designing a
WSDL file. A skeleton source code from the WSDL file is then
generated by using a Web Services tool such as Apache Axis. The
generated skeleton code is just a template of the Web Services
provider's source code. Therefore, even though the Web Services
provider's skeleton code works on its own, if additional functions
were necessary, the generated skeleton code would require additional
source codes. This approach is superior to the bottom-up approach in
terms of interoperability because the specification is already
defined in the WSDL file. All vendors have to be in compliance with
the WSDL file.

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In contrast, the bottom-up approach is carried out by first creating
Web Services from source code (e.g., Java bean) and then generating a
WSDL file from the source code by using a Web Services tool such as
Axis. This approach is faster and easier than the top-down approach.
However, in the bottom-up approach, it is difficult to ensure
interoperability since implementation of a Web Services becomes
vendor-specific.

When developing a NETCONF server, the WSDL file is already defined in
[RFC4743], so there is no choice but to develop the NETCONF server
using the top-down approach. The remainder of this section describes
the top-down approach for developing a NETCONF server.

To develop a SOAP-based NETCONF server using the top-down approach, a
skeleton code is necessary. A skeleton is a library, which is also
generated automatically from WSDL by a Web Services tool. When using
Axis as a Web Services tool, the generated skeleton is in the form of
a Java library. From the same WSDL file as that used for generating
the stub code, skeleton codes are generated in files such as
"NetconfBindingSkeleton.java", "Hello.java", and
"GetConfigType.java".

When skeleton codes are being generated, the development environment
may be arranged as well. Moreover, when a Java-based NETCONF server
is being developed, in addition to JDK and Axis, a servlet container
such as Apache Tomcat [Tomcat] is necessary. The "webapps\axis"
directory under the Axis directory has to be copied to the "webapps"
directory under the Tomcat directory.

4.2.1. Developing NETCONF Servers without Eclipse

Given that the development environment of a NETCONF server is created
in the environment of a Windows computer without Eclipse and
"myNetconfService.wsdl" is placed in the "C:\NetconfServer"
directory, a skeleton is generated by executing the following command
in the command prompt.

C:\NetconfServer>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
\lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
0.2.jar;%AXIS_HOME%\lib\wsdl4j-1.5.1.jar
org.apache.axis.wsdl.WSDL2Java -p skeleton -s -S true -d Session
myNetconfService.wsdl

In the directory where the WSDL file is located, a WSDL2Java command
is executed. Locations of each Axis library should be specified.
The environment variable of "AXIS_HOME" is a directory where Axis is
installed. By executing the above command, files with an extension

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of "*.java" are generated in the "skeleton" directory, which is
specified in the above command. Inside the skeleton directory, files
such as "NetconfBindingSkeleton.java", "Hello.java", and
"GetConfigType.java" exist. Furthermore, files named "deploy.wsdd"
and "undeploy.wsdd" are found. "Deploy.wsdd" and "undeploy.wsdd" are
used when deploying a NETCONF server in a servlet container and when
undeploying a NETCONF server from a servlet container, respectively.

Adding source codes of NETCONF server functions to skeleton codes
such as "NetconfBindingImpl.java" is required as the need arises.
Functions such as the release of log messages have to be added at
this stage. After that, by executing the following command in the
command prompt, compilation of java files is carried out. Doing so
will generate "*.class" files.

C:\NetconfServer>javac -classpath .;%AXIS_HOME%\lib\axis.jar;%
AXIS_HOME%\lib\jaxrpc.jar skeleton/*.java

A NETCONF server can be developed by following the above-described
procedures. These class files should be copied into the directory
"webapps\axis\WEB-INFO\classes" of the Apache Tomcat directory.
Finally, the NETCONF server is deployed by executing the following
command.

C:\NetconfServer>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
\lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
0.2.jar org.apache.axis.client.AdminClient -p 832 depoy.wsdd

The command is executed in the directory where "deploy.wsdd" is
located. The file "deploy.wsdd" is generated at the same time the
skeleton code is generated. After deployment, the NETCONF server
receives NETCONF messages sent from the NETCONF client.

4.2.2. Developing NETCONF Servers Using Eclipse

When Eclipse and Apache Ant are used, the procedures described in the
previous section are significantly simplified and executed at one
time. Files named "build.xml" and "build.properties" are required
for Apache Ant. Examples of "build.xml" and "build.properties" are
shown in Figure 6 and Figure 7, respectively.

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<?xml version="1.0"?>
<project name="NetconfService" default="all" basedir=".">
<property file="build.properties"/>
<path id="axis-classpath">
<fileset dir="${axis.libdir}">
<include name="*.jar"/>
</fileset>
</path>
<target name="prepare">
<mkdir dir="${srcdir}"/>
<mkdir dir="${destdir}"/>
</target>
<target name="skeleton" depends="prepare">
<java classname="org.apache.axis.wsdl.WSDL2Java" fork
="Yes">
<arg value="-p"/>
<arg value="${skeletondir}"/>
<arg value="-o"/>
<arg value="${srcdir}"/>
<arg value="-s"/>
<arg value="-S"/>
<arg value="true"/>
<arg value="-d"/>
<arg value="Session"/>
<arg value="${wsdlpath}"/>
<classpath refid="axis-classpath"/>
</java>
</target>
<target name="compile" depends="skeleton">
<javac srcdir="${srcdir}" destdir="${destdir}"
encoding="UTF-8">
<classpath refid="axis-classpath"/>
</javac>
</target>
<target name="copy2axis" depends="compile">
<copy todir="${tomcat.axis.classesdir}" overwrite=
"true">
<fileset dir="${destdir}">
<include name="*.class"/>
<include name="*/*.class"/>
<include name="*/*/*.class"/>
</fileset>
</copy>
</target>
<target name="deploy" depends="copy2axis">
<java classname="org.apache.axis.client.AdminClient"
fork="Yes">
<arg value="-p"/>

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<arg value="${deploy.port}"/>
<arg value="${deploy.ddname}"/>
<classpath refid="axis-classpath"/>
</java>
</target>
<target name="all" depends="deploy"/>
</project>

Figure 6: build.xml of NETCONF Servers

axis.libdir=C:/axis-1_4/lib
tomcat.axis.classesdir=
C:/Program Files/Apache Software Foundation/Tomcat 6.0/
webapps/axis/WEB-INF/classes
srcdir=src
destdir=classes
skeletondir=skeleton
wsdlpath=myNetconfService.wsdl
deploy.port=832
deploy.ddname=src/skeleton/deploy.wsdd

Figure 7: build.properties of NETCONF Servers

The locations of the WSDL file and "deploy.wsdd" file have to be
specified in the "build.properties" file. In Figure 7, the location
of the WSDL file and "deploy.wsdd" file are specified as being under
the current directory.

By running Apache Ant on Eclipse, the steps shown in Figure 6 are
followed. First, skeleton codes have to be generated. After the
skeleton codes are generated, source codes of the NETCONF server
functions may be added to the skeleton codes according to the
functions that developers intend to add.

Then, by running Apache Ant again, compiling of the skeleton codes is
executed. As a result, class files of the NETCONF server are
generated. Apache Ant copies these class files to the directory of
Tomcat and deploys the NETCONF server. After that, the NETCONF
server becomes accessible by the NETCONF client.

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4.2.3. Developing NETCONF Servers with C Programming Language

When the NETCONF server for network equipment is being implemented,
memory capacity might be limited, so it might not be possible to
install a Java environment on the network equipment. The network-
equipment platform might not support a Web Services tool. In that
case, it may be necessary to implement SOAP as well as the NETCONF
server by using C programming language on the network equipment.

To develop a NETCONF server capable of receiving NETCONF messages
sent over SOAP/HTTP, the network equipment may have an HTTP daemon
and a NETCONF service provider. A commonly used HTTP daemon can be
used. A SOAP module may be added to the HTTP daemon as a connector
between the HTTP daemon and the NETCONF service provider. The
NETCONF service provider for parsing NETCONF messages sent from the
NETCONF client and sending reply NETCONF messages toward the NETCONF
client may be developed.

When an HTTP daemon receives a SOAP message that is sent over HTTP,
the message is handed over to the SOAP module incorporated in the
HTTP daemon. Then, the SOAP module removes the SOAP header and
passes NETCONF messages to the NETCONF service provider. After that,
the NETCONF service provider parses the NETCONF messages and
configures the network equipment accordingly.

5. Security Considerations

The security considerations of [RFC4741] and [RFC4743] are applicable
in this document. Implementers or users of SOAP-based NETCONF
clients and servers should take these considerations into account.

As specified in the security considerations section of [RFC4743],
transport-level security, such as authentication of users and
encryption of transport protocol, has to be ensured by TLS (Transport
Layer Security) in the case of NETCONF SOAP binding. That is,
security has to be provided in the form of NETCONF/SOAP/HTTPS.

6. Acknowledgements

Extensive input was received from the members of the NETCONF design
team, including: Andy Bierman, Simon Leinen, Bert Wijnen, Mehmet
Ersue, Ted Goddard, Ray Atarashi, Ron Bonica, and Dan Romascanu. The
following people have also reviewed this document and provided
valuable input: Jari Arkko, Pasi Eronen, Chris Newman, Tim Polk,
David Ward, Magnus Westerlund, and Christian Vogt.

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RFC 5381 Experience of Implementing NETCONF/SOAP October 2008

7. References

7.1. Normative References

[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.

[RFC4743] Goddard, T., "Using NETCONF over the Simple Object Access
Protocol (SOAP)", RFC 4743, December 2006.

7.2. Informative References

[Ant] "Apache Ant".
<http://ant.apache.org/>

[Axis] "Web Services - Axis".
<http://ws.apache.org/axis/>

[Eclipse] "Eclipse".
<http://www.eclipse.org/>

[JDK] "Java SE".
<http://java.sun.com/javase/index.jsp>

[NetBeans] "NetBeans".
<http://www.netbeans.org/index.html>

[RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF
Configuration Protocol over Secure SHell (SSH)",
RFC 4742, December 2006.

[RFC4744] Lear, E. and K. Crozier, "Using the NETCONF Protocol over
the Blocks Extensible Exchange Protocol (BEEP)",
RFC 4744, December 2006.

[Tomcat] "Apache Tomcat".
<http://tomcat.apache.org/>

[WSDL] "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: +81-44-549-1735
Fax: +81-44-549-1272
EMail: [email protected]

Yoshifumi Atarashi
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan

Phone: +81-44-549-1735
Fax: +81-44-549-1272
EMail: [email protected]

Hiroyasu Kimura
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan

Phone: +81-44-549-1735
Fax: +81-44-549-1272
EMail: [email protected]

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RFC 5381 Experience of Implementing NETCONF/SOAP October 2008

Makoto Kitani
Alaxala Networks Corp.
Shin-Kawasaki Mitsui Bldg.
890 Saiwai-ku Kashimada
Kawasaki, Kanagawa 212-0058
Japan

Phone: +81-44-549-1735
Fax: +81-44-549-1272
EMail: [email protected]

Hideki Okita
Hitachi, Ltd.
1-280 Higashi-Koigakubo
Kokubunji, Tokyo 185-8601
Japan

Phone: +81-42-323-1111
Fax: +81-42-327-7868
EMail: [email protected]

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RFC 5381 Experience of Implementing NETCONF/SOAP October 2008

Full Copyright Statement

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contained in BCP 78, and except as set forth therein, the authors
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