kamailio/modules/xmlrpc/doc/xmlrpc.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<section id="xmlrpc" xmlns:xi="http://www.w3.org/2001/XInclude">
    <sectioninfo>
	<authorgroup>
		<author>
		<firstname>Jan</firstname>
		<surname>Janak</surname>
		<affiliation><orgname>iptelorg GmbH</orgname></affiliation>
		<address>
			<email>[email protected]</email>
		</address>
		</author>
	</authorgroup>
	<copyright>
		<year>2005</year>
		<holder>iptelorg GmbH</holder>
	</copyright>
	<revhistory>
		<revision>
		<revnumber>$Revision$</revnumber>
		<date>$Date$</date>
		</revision>
	</revhistory>
	</sectioninfo>


	<section id="xmlrpc.design">
	<title>Design Goals</title>
	<para>
	    
	</para>
	<itemizedlist>
	    <listitem>
		<para>Implemented as a module.</para>
	    </listitem>
	    <listitem>
		<para>API independent of transport protocols.</para>
	    </listitem>
	    <listitem>
		<para>Reuse transports available in SER.</para>
	    </listitem>
	    <listitem>
		<para>The possibility to encrypt all communication.</para>
	    </listitem>
	    <listitem>
		<para>The possibility to authenticate clients.</para>
	    </listitem>
	    <listitem>
		<para>Easy integration with existing languages and
		    implementations.</para>
	    </listitem>
	    <listitem>
		<para>
		    Easy and straightforward implementation of management
		    functions in SER modules.
		</para>
	    </listitem>
	</itemizedlist>
	</section>

	<section id="xmlrpc.overview">
	<title>Overview of Operation</title>
	<para>
		This module implements the XML-RPC transport and encoding interface
		for ser RPCs.
	</para>
	<para>
	    The XML-RPC protocol encodes the name of the method
	    to be called along with its parameter in an XML document which is
	    then conveyed using HTTP (Hyper Text Transfer Protocol) to the
	    server. The server will extract the name of the function to be
	    called along with its parameters from the XML document, execute the
	    function, and encode any data returned by the function into another
	    XML document which is then returned to the client in the body of a
	    200 OK reply to the HTTP request.
	</para>
	<para>
	    XML-RPC is similar to more popular <ulink
		url="http://www.w3.org/TR/soap/">SOAP</ulink> (Simple Object
		Access Protocol), which is an XML-based messaging framework
		used in Web Services developed within the <ulink
		url="http://www.w3c.org">World Wide Web
		Consortium</ulink>. Both protocols are using HTTP as the
		transport protocol for XML documents, but XML-RPC is much
		simpler and easier to implement than SOAP.
	</para>
	<para>
	    Here is an example of single XML-RPC function call to determine
	    current time:
	</para>
	<programlisting>
<![CDATA[
POST /RPC2 HTTP/1.0
User-Agent: Radio UserLand/7.1b7 (WinNT)
Host: time.xmlrpc.com
Content-Type: text/xml
Content-length: 131
	    
<?xml version="1.0"?>
<methodCall>
<methodName>currentTime.getCurrentTime</methodName>
<params>
</params>
</methodCall>
]]>
	</programlisting>
	<para>
	    And the response returned by the server:
	</para>
	<programlisting>
<![CDATA[
HTTP/1.1 200 OK
Connection: close
Content-Length: 183
Content-Type: text/xml
Date: Wed, 03 Oct 2001 15:53:38 GMT
Server: UserLand Frontier/7.0.1-WinNT

<?xml version="1.0"?>
<methodResponse>
<params>
<param>
<value><dateTime.iso8601>20011003T08:53:38</dateTime.iso8601>
</value>
</param>
</params>
</methodResponse>
]]>
	</programlisting>
	<para>
	    XML-RPC specification spells HTTP as the official transport
	    protocol for XML-RPC documents. SER does not directly support
	    HTTP, it is a SIP server so SIP is the only protocol supported by
	    SER. Because we would like to reuse all transport protocols
	    available in SER, such as TCP and TLS, it would be natural to use
	    modified version of XML-RPC which would run on top of SIP instead
	    of HTTP. XML-RPC documents would be then encoded in the bodies of
	    SIP requests and replies would be sent by the server in the bodies of
	    SIP replies. This way we could reuse all transport protocols
	    (including UDP) and message parsers available in SER.
	</para>
	<para>
	    Although this approach seems to be the logical choice, there is one
	    big drawback. No existing XML-RPC implementations support SIP as the
	    transport protocol, and there are many existing implementations
	    available for vast majority of existing languages. See the <ulink
	    url="http://www.xmlrpc.com/directory/1568/implementations">XML-RPC
	    implementation page</ulink> for more details. Extending existing
	    implementations with SIP support would not be easy.
	</para>
	<para>
	    Because  extending available XML-RPC implementation would be too
	    expensive, we could also do it the other way around, keep existing
	    XML-RPC implementations and extend SER to support HTTP. Extending
	    SER with HTTP support is easier than it might seem at a first
	    glance, due to the similarity between SIP requests and HTTP
	    requests.
	</para>
	<para>
	    SER already supports TCP, so existing HTTP implementations can send
	    HTTP requests to it. HTTP requests are missing certain mandatory
	    SIP header fields, such as Via, From, and CSeq. The contents of the
	    header fields is mainly used for transaction matching. A SIP server
	    could perform two basic operations when processing an HTTP
	    request:
	    <itemizedlist>
		<listitem>
		    <para>
			Terminate the request, execute the function and send a
			reply back.
		    </para>
		</listitem>
		<listitem>
		    <para>
			Forward the request to another SIP server.
		    </para>
		</listitem>
	    </itemizedlist>
	</para>
	<para>
	    Nothing special is needed on the SIP server terminating the
	    request, except that it has to know where it should send the
	    reply. Parsing of HTTP header field bodies would fail because we do
	    not have parsers for them in SER, but that does not matter anyway
	    because all the information is encoded in the body of the
	    request. HTTP requests contain no Via header fields. Via header
	    fields are used by SIP implementations to determine the destination
	    (IP, transport protocol, and port number) for replies. When
	    processing HTTP requests the SIP server needs to create a fake Via
	    header field based on the source IP address and port number of the
	    TCP connection. The SIP server will use this information when
	    sending a reply back.
	</para>
	<para>
	    Forwarding of HTTP requests by SIP proxies is a little bit more
	    complicated and there are several limitations. First of all, we can
	    only use stateless forwarding, no transactional forwarding, because
	    HTTP requests do not contain all the header fields needed for
	    transaction matching. Any attempt to call t_relay on an HTTP
	    requests would fail. HTTP requests always use TCP and thus we could
	    use stateless forwarding on the SIP server, provided that the
	    request will be also forwarded over TCP. Stateless forwarding does
	    not require the mandatory header fields (which are missing here)
	    and it would work. In addition to that, the SIP server would also
	    append fake Via header field to the request and change the contents
	    of the Request-URI. The Request-URI of HTTP requests sent by XML-RPC
	    implementations typically contain something like "/RPC2" and the
	    first SIP server processing the request should rewrite the value
	    with a valid SIP URI.
	</para>
	<para>
	    <xref linkend="fig.rpc_example"/> shows a scenario which involves
	    two SIP servers, one performs HTTP request "normalization" and
	    forwarding, and the other terminates the request, executes
	    corresponding function, and generates a reply.
	</para>
	<mediaobject id="fig.rpc_example" xreflabel="Figure RPC Example">
	    <imageobject>
		<imagedata align="center" fileref="rpc_example.png" format="PNG"/>
	    </imageobject>
	    <textobject>
		<para>Example RPC Scenario</para>
	    </textobject>
	    <caption>
		Example RPC Scenario
	    </caption>
	</mediaobject>
	<para>
	    <emphasis>Step 1.</emphasis> An HTTP user agent sends an ordinary
	    HTTP request to a SIP server. The user agent can either establish a
	    connection directly to port 5060 or the SIP server can be
	    configured to listen on port 80. The request contains standard HTTP
	    headers and an XML-RPC document in the body:
	    <programlisting>
<![CDATA[
POST / HTTP/1.0.
Host: localhost:5060
User-Agent: xmlrpclib.py/1.0.1 (by www.pythonware.com)
Content-Type: text/xml
Content-Length: 111

<?xml version='1.0'?>
<methodCall>
<methodName>]]><emphasis>usrloc.statistics</emphasis><![CDATA[</methodName>
<params>
</params>
</methodCall>
]]>
	    </programlisting>
	    This particular request calls method "statistics" from from usrloc
	    module of SER. The method has no parameters.
	</para>
	<para>
	    The outbound SIP server receives the HTTP request and performs a
	    set of actions called "SIP-normalization". This includes creation
	    of fake Via header field based on the source IP and port of the TCP
	    connection, looking up of the target SIP server that should
	    terminate and process the request, and rewriting of the Request-URI
	    with the SIP URI of the target SIP server. Modified HTTP request
	    will be then forwarded statelessly to the target SIP server.
	    <programlisting>
POST <emphasis>sip:proxy01.sip-server.net</emphasis> HTTP/1.0
<emphasis>Via: SIP/2.0/TCP 127.0.0.1:3571</emphasis>
Host: localhost:5060
User-Agent: xmlrpclib.py/1.0.1 (by www.pythonware.com)
Content-Type: text/xml
Content-Length: 111
<![CDATA[
<?xml version='1.0'?>
<methodCall>
<methodName>usrloc.statistics</methodName>
<params>
</params>
</methodCall>
]]>
	    </programlisting>
	</para>
	<para>
	    <emphasis>Step 2.</emphasis> "normalized" HTTP request is
	    statelessly forwarded to the target SIP server over TCP.
	</para>
	<para>
	    <emphasis>Step 3.</emphasis> The target SIP server receives the
	    HTTP request and executes function called
	    <function>dispatch_rpc</function> from xmlrpc SER module. This
	    function will parse the XML-RPC document in the body of the request
	    and lookup the function to be called among all RPC functions
	    exported by the SER core and modules. Function
	    <function>dispatch_rpc</function> will be called from the
	    configuration file just like any other function:
	    <programlisting>
if (method == "POST" || method == "GET") {
    <emphasis>dispatch_rpc();</emphasis>
    break;
};
	    </programlisting>
	    This particular configuration snippet executes the function
	    whenever SER receives GET or POST requests. These two method names
	    indicate HTTP.
	</para>
	<para>
	    <emphasis>Step 4.</emphasis> The function
	    <function>dispatch_rpc</function> scans through the list of all
	    exported RPC functions searching for the
	    <function>statistics</function> function of the usrloc module. The
		<ulink url='http://sip-router.org/docbook/sip-router/branch/master/rpc/ser_rpc.html'>
		SER RPC Module API</ulink>
		describes in detail how modules export RPC functions.
	</para>
	<para>
	    <emphasis>Step 5.</emphasis> As the RPC function from usrloc module
	    is running and gathering statistics, it calls functions of RPC
	    interface to prepare the result for the caller.
	</para>
	<para>
	    <emphasis>Step 6.</emphasis> Once the RPC function finishes, xmlrpc
	    module will build the XML-RPC document from the data received from
	    usrloc module and generate a reply which will be sent to the caller.
	</para>
	<para>
	    <emphasis>Steps 7. and 8.</emphasis> HTTP reply is sent back to the
	    caller and the remote procedure call finishes.
	    <programlisting>
<![CDATA[
HTTP/1.0 200 OK
Via: SIP/2.0/TCP 127.0.0.1:3571
Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))
Content-Length: 651
Warning: 392 127.0.0.1:5060 "Noisy feedback tells:  pid=9975 req_src_ip=127.0.0
1 req_src_port=3571 in_uri=/ out_uri=sip:proxy01.sip-server.net via_cnt==1"

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<params>
<param><value><array><data>
<value><struct>
<member><name>domain</name>
<value><string>aliases</string></value></member>
<member><name>users</name>
<value><i4>0</i4></value></member>
<member><name>expired</name>
<value><i4>0</i4></value></member>
</struct></value>
<value><struct>
<member><name>domain</name>
<value><string>location</string></value></member>
<member><name>users</name>
<value><i4>0</i4></value></member>
<member><name>expired</name>
<value><i4>0</i4></value></member>
</struct></value>
</data></array></value></param>
</params>
</methodResponse>
]]>
	    </programlisting>
	</para>
	<note>
	    <para>
		The scenario described on <xref linkend="fig.rpc_example"/>
		involves two SIP servers. This is just to demonstrate that in
		setups containing more SIP servers it is possible to forward
		HTTP requests from one SIP server to another and use standard
		SIP routing mechanisms to decide which SIP server should
		process the request. There is no need to have multiple SIP
		servers in simple setups, because one SIP server can both add 
		fake Via header field and process the RPC at the same
		time. Modified configuration file snipped could then look like
		this:
		<programlisting>
if (method == "POST" || method == "GET") {
    <emphasis>dispatch_rpc();</emphasis> # Process the request
    break;
};
		</programlisting>
	    </para>
	</note>
    </section>



	<section id="xmlrpc.implementation">
	<title>XML-RPC Implementation</title>
	<para>
	    The purpose of the functions of this module is to convert XML-RPC
	    document carried in the body of HTTP requests into data returned by
	    the RPC interface and back. The module also contains functions
	    necessary to "normalize" HTTP requests. The module uses <ulink
		url="http://xmlrpc-c.sourceforge.net">xmlrpc-c</ulink>
	    library to perform XML-RPC related functions.
	</para>
	<para>
	    The module always returns 200 OK HTTP reply, it will never return
	    any other HTTP reply. Failures are expressed in XML-RPC documents
	    in the body of the reply. There is basic method introspection
	    support in the module. Currently the module can list all functions
	    exported by the server and for each function it can return the
	    documentation string describing the function.
	</para>
	<section id="xmlrpc.implementation.requests">
	    <title>Requests</title>
	    <para>
		Requests processed by the module are standard XML-RPC requests
		encoded in bodies of HTTP requests.
		<programlisting>
<![CDATA[
POST / HTTP/1.0
Host: localhost:5060
User-Agent: xmlrpclib.py/1.0.1 (by www.pythonware.com)
Content-Type: text/xml
Content-Length: 112

<?xml version='1.0'?>
<methodCall>
]]><emphasis><![CDATA[<methodName>system.listMethods</methodName>]]></emphasis><![CDATA[
<params>
</params>
</methodCall>
]]>
		</programlisting>
		The name of the method to be called in this example is
		"listMethods". This is one of the introspection methods. SER
		will call <function>dispatch_rpc</function> function of xmlrpc
		module to handle the request. The function will parse the
		XML-RPC document, lookup <function>listMethods</function>
		function in the list of all export RPC functions, prepare the
		context for the function and execute it.
	    </para>
	</section>
	<section id="xmlrpc.implementation.replies">
	    <title>Replies</title>
	    <para>
		The module will always generate 200 OK. Other response codes
		and classes are reserved for SER. The status code of the
		XML-RPC reply, response code, and additional data will be
		encoded in the body of the reply. Failure replies do not
		contain any data, just the response code and reason phrase:
		<programlisting>
<![CDATA[
HTTP/1.0 200 OK
Via: SIP/2.0/TCP 127.0.0.1:2464
Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))
Content-Length: 301

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
]]><emphasis><![CDATA[
<fault>
<value><struct>
<member><name>faultCode</name>
<value><i4>501</i4></value></member>
<member><name>faultString</name>
<value><string>Method Not Implemented</string></value></member>
</struct></value>
</fault>
]]></emphasis><![CDATA[
</methodResponse>
]]>
		</programlisting>
		This particular reply indicates that there is no such RPC
		method available on the server.
	    </para>
	    <para>
		Success replies always contain at least one return value. In
		our case the simplest success replies contain single boolean
		with value 1:
		<programlisting>
<![CDATA[
HTTP/1.0 200 OK
Via: SIP/2.0/TCP 127.0.0.1:4626
Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))
Content-Length: 150

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<params>
]]><emphasis><![CDATA[<param><value><boolean>1</boolean></value></param>]]></emphasis><![CDATA[
</params>
</methodResponse>
]]>
		</programlisting>
		This is exactly how the reply looks like when an RPC function
		does not add any data to the reply set.
	    </para>
	    <para>
		If an RPC function adds just a single item (it calls
		<function>add</function> once
		with just one character in the formatting string) then the data
		will be converted to XML-RPC representation according to the
		rules described in
		<ulink url='http://sip-router.org/docbook/sip-router/branch/master/rpc/ser_rpc.html#rpc.data_types'>
		SER RPC Type Conversion</ulink> and
		the reply will contain just the single value:
		<programlisting>
<![CDATA[
HTTP/1.0 200 OK
Via: SIP/2.0/TCP 127.0.0.1:3793
Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))
Content-Length: 216

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<params>
]]><emphasis><![CDATA[<param><value><string>Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))</string></value></param>]]></emphasis><![CDATA[
</params>
</methodResponse>
]]>
		</programlisting>
	    </para>
	    <para>
		If an RPC function adds more than one data items to the result
		set then the module will return an array containing all the
		data items:
		<programlisting>
<![CDATA[
HTTP/1.0 200 OK
Via: SIP/2.0/TCP 127.0.0.1:2932
Server: Sip EXpress router (0.10.99-janakj_experimental (i386/linux))
Content-Length: 276

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<params>
<param><value>]]><emphasis><![CDATA[<array><data>
<value><string>./ser</string></value>
<value><string>-f</string></value>
<value><string>ser.cfg</string></value>
</data></array>]]></emphasis><![CDATA[</value></param>
</params>
</methodResponse>
]]>
		</programlisting>
		This is probably the most common scenario.
	    </para>
	</section>
	<section id="xmlrpc.implementation.type_conversion">
	    <title>Type Conversion</title>
	    <para>
		The data types of the RPC API are converted to the data types
		of XML-RPC and vice versa. <xref
		linkend="tab.type_conversion"/> shows for each RPC API data
		type corresponding XML-RPC data type.
		<table id="tab.type_conversion">
		    <title>Data Type Conversion</title>
		    <tgroup cols="3">
			<tbody>
			    <row>
				<entry>RPC API</entry>
				<entry>XML-RPC</entry>
				<entry>RPC Example</entry>
				<entry>XML-RPC Example</entry>
			    </row>
			    <row>
				<entry>Integer</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<i4></i4>
					]]>
				    </markup>
				</entry>
				<entry>rpc->add("d", 42)</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<i4>42</i4>
					]]>
				    </markup>
				</entry>
			    </row>
			    <row>
				<entry>Float</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<double></double>
					]]>
				    </markup>
				</entry>
				<entry>rpc->add("f", -12.214)</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<double>-12.214</double>
					]]>
				    </markup>
				</entry>
			    </row>
			    <row>
				<entry>String</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<string></string>
					]]>
				    </markup>
				</entry>
				<entry>rpc->add("s","Don't panic")</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<string>Don't panic</string>
					]]>
				    </markup>
				</entry>
			    </row>
			    <row>
				<entry>Struct</entry>
				<entry>
				    <markup role="xmlrpc">
					<![CDATA[
					<struct></struct>
					]]>
				    </markup>
				</entry>
				<entry>rpc->struct_add(handle,"sd","param1",42,"param2",-12.214)</entry>
				<entry>
				    <programlisting>
<![CDATA[
<struct>
  <member>
    <name>param1</name>
    <value>
      <i4>42</i4>
    </value>
  </member>
  <member>
    <name>param2</name>
    <value>
      <double>-12.214</i4>
    </value>
  </member>
</struct>
]]>
				    </programlisting>
				</entry>
			    </row>
			</tbody>
		    </tgroup>
		</table>
	    </para>
	</section>
	<section id="xmlrpc.implementation.limitations">
	    <title>Limitations</title>
	    <para>
		SER xmlrpc modules does not implement all data types allowed in
		XML-RPC. As well it does not implement arrays and nested
		structures. This simplification is a feature, not bug. In our
		case the XML-RPC interface will be used mainly for management
		purposes and we do not need all the bells and whistles of
		XML-RPC. Parsing and interpreting nested structures is
		complex and we try to avoid it.
	    </para>
	</section>
	<section id="xmlrpc.interoperability_problems">
	    <title>Interoperability Problems</title>
	    <para>
		Due to a bug in Python xmlrpclib there is an interoperability 
		problem with basic clients using it: by default an xmlrpclib client 
		expects the server to immediately close the connection after answering
		and if the server does not close the connections the xmlrpclib client
		will wait forever.
		</para>
		<para>
		There are 2 ways to work around this problem: write a "fixed"
		Transport class and initialize xmlpclib using it (recommended) or
		make ser close the tcp connection after each request.
		</para>
		<para>
		The <ulink url='http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules_s/xmlrpc/examples/xmlrpc_test.py'>
		examples/xmlrpc_test.py
		</ulink> provides a very simple example of using xmlrpclib with a
		Transport class that works.
		</para>
		<para>
		For the second solution (force closing tcp connections after answering)
		the XMLRPC route should have a <function>set_reply_close()</function>
		command before <function>dispatch_rpc()</function>.
		<function>set_reply_no_connect()</function> is also recommended
		(avoid trying to open tcp connection to xmlrpc clients that closed it).
		Alternatively ending the XMLRPC route with return -1, exit -1 or
		drop -1 can also be used, but note that this will not work for 
		async rpcs (it will close the connection immeidately and not on the
		async response).
		<example>
		<programlisting>
<![CDATA[
route[XMLRPC]{
	# close connection only for xmlrpclib user agents
	if search("^User-Agent:.*xmlrpclib"))
		set_reply_close();
	set_reply_no_connect(); # optional
	dispatch_rpc();
}
]]>
		</programlisting>
		</example>
		</para>
	    <para>
		Another common problem is CRLF handling. According to the xml spec
		CR ('\r') must be escaped (to &amp;#xD;) or they will be "normalized"
		when parsing the xml document. However some xmlrpc clients do not
		follow this rule (e.g. clients based on the python or php xmlrpclib)
		and send CRLF unescaped. A possible workaround is to enable
		automatic LFLF to CRLF conversion (using the
		<varname>double_lf_to_crlf</varname> modules parameter) and replace
		CRLF with LFLF in the client queries.
		</para>
	</section>
    </section>

	<section id="xmlrpc.client_examples">
	<title>Client Examples</title>
	<!-- TODO:
	    implement clients in various languages 
	- pros, cons 
	- How failures
	    are mapped to XMLRPC 
	- How success replies are mapped 
	- How data
	    types of the API are mapped to XMLRPC elements 
	- 200 OK with no
	    data transformed to one value - True
	-->
	<para>
	<itemizedlist>
		<listitem><para>
			<ulink url='http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules_s/xmlrpc/examples/xmlrpc_test.pl'>
			<emphasis>examples/xmlrpc_test.pl</emphasis>
			</ulink> (basic perl application that builds and sends an
			<emphasis>XMLRPC</emphasis> request from its commandline
			parameters).
		</para></listitem>
		<listitem><para>
			<ulink url='http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules_s/xmlrpc/examples/xmlrpc_test.py'>
			<emphasis>examples/xmlrpc_test.py</emphasis>
			</ulink> (basic python application that builds and sends an
			<emphasis>XMLRPC</emphasis> request from its commandline
			parameters).
		</para></listitem>
		<listitem><para>
			<ulink url='http://git.sip-router.org/cgi-bin/gitweb.cgi?p=ser;a=tree;f=ser_ctl'>
			<emphasis>ser_ctl</emphasis>
			</ulink>
			(complex python application that 
			uses the <emphasis>XML-RPC</emphasis> interface implemented by the
			<emphasis>xmlrpc</emphasis> module).
		</para></listitem>
		<listitem><para>
			<ulink uri='http://www.iptel.org/serweb'>
			<emphasis>serweb</emphasis>
			</ulink>
			(php application that can use
			the <emphasis>XML-RPC</emphasis> interface to call ser 
			functions).
		</para></listitem>
	</itemizedlist>
	</para>
    </section>

	<xi:include href="params.xml"/>
	<xi:include href="functions.xml"/>

</section>