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c248bffd54
* src/ejabberd_c2s.erl: Better handling of malformed JIDs * src/mod_register.erl (try_register/2): Now returns "jid malformed" error if user name is invalid SVN Revision: 174
365 lines
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365 lines
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<HEAD><TITLE>Ejabberd Developers Guide</TITLE>
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<!--PREFIX <ARG ></ARG>-->
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<!--CUT DEF section 1 -->
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<H1 ALIGN=center>Ejabberd Developers Guide</H1>
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<H3 ALIGN=center>Alexey Shchepin<BR>
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<A HREF="mailto:alexey@sevcom.net"><TT>mailto:alexey@sevcom.net</TT></A><BR>
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<A HREF="xmpp:aleksey@jabber.ru"><TT>xmpp:aleksey@jabber.ru</TT></A></H3>
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<H3 ALIGN=center>September 10, 2003</H3><DIV ALIGN=center>
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<IMG SRC="logo.png">
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</DIV><BR>
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<BR>
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<!--TOC section Table of Contents-->
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<H2>Table of Contents</H2><!--SEC END -->
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<UL><LI>
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<A HREF="#htoc1">1 Introduction</A>
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<UL><LI>
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<A HREF="#htoc2">1.1 How it works</A>
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<UL><LI>
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<A HREF="#htoc3">1.1.1 Router</A>
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<LI><A HREF="#htoc4">1.1.2 Local Router</A>
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<LI><A HREF="#htoc5">1.1.3 Session Manager</A>
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<LI><A HREF="#htoc6">1.1.4 S2S Manager</A>
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</UL>
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</UL>
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<LI><A HREF="#htoc7">2 XML representation</A>
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<LI><A HREF="#htoc8">3 Module <TT>xml</TT></A>
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<LI><A HREF="#htoc9">4 <TT>ejabberd</TT> modules</A>
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<UL><LI>
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<A HREF="#htoc10">4.1 <CODE>gen_mod</CODE> behaviour</A>
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<LI><A HREF="#htoc11">4.2 Module <CODE>gen_iq_handler</CODE></A>
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<LI><A HREF="#htoc12">4.3 Services</A>
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</UL>
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</UL>
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<!--TOC section Introduction-->
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<H2><A NAME="htoc1">1</A> Introduction</H2><!--SEC END -->
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<A NAME="sec:intro"></A>
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<TT>ejabberd</TT> is a Free and Open Source fault-tolerant distributed Jabber
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server. It is writen mostly in Erlang.<BR>
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<BR>
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The main features of <TT>ejabberd</TT> is:
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<UL><LI>
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Works on most of popular platforms: *nix (tested on Linux and FreeBSD)
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and Win32
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<LI>Distributed: You can run <TT>ejabberd</TT> on a cluster of machines and all of
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them will serve one Jabber domain.
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<LI>Fault-tolerance: You can setup an <TT>ejabberd</TT> cluster so that all the
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information required for a properly working service will be stored
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permanently on more than one node. This means that if one of the nodes
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crashes, then the others will continue working without disruption.
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You can also add or replace more nodes ``on the fly''.
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<LI>Built-in <A HREF="http://www.jabber.org/jeps/jep-0045.html">Multi-User
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Chat</A> service
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<LI>Built-in IRC transport
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<LI>Built-in
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<A HREF="http://www.jabber.org/jeps/jep-0060.html">Publish-Subscribe</A>
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service
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<LI>Built-in Jabber Users Directory service based on users vCards
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<LI>Support for
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<A HREF="http://www.jabber.org/jeps/jep-0030.html">JEP-0030</A>
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(Service Discovery).
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<LI>Support for
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<A HREF="http://www.jabber.org/jeps/jep-0039.html">JEP-0039</A>
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(Statistics Gathering).
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<LI>Support for <TT>xml:lang</TT> attribute in many XML elements
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</UL>
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<!--TOC subsection How it works-->
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<H3><A NAME="htoc2">1.1</A> How it works</H3><!--SEC END -->
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<A NAME="sec:howitworks"></A>
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A Jabber domain is served by one or more <TT>ejabberd</TT> nodes. These nodes can
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be run on different machines that are connected via a network. They all must
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have the ability to connect to port 4369 of all another nodes, and must have
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the same magic cookie (see Erlang/OTP documentation, in other words the file
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<TT>~ejabberd/.erlang.cookie</TT> must be the same on all nodes). This is
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needed because all nodes exchange information about connected users, S2S
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connections, registered services, etc...<BR>
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<BR>
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Each <TT>ejabberd</TT> node have following modules:
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<UL><LI>
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router;
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<LI>local router.
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<LI>session manager;
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<LI>S2S manager;
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</UL>
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<!--TOC subsubsection Router-->
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<H4><A NAME="htoc3">1.1.1</A> Router</H4><!--SEC END -->
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This module is the main router of Jabber packets on each node. It routes
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them based on their destinations domains. It has two tables: local and global
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routes. First, domain of packet destination searched in local table, and if it
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found, then the packet is routed to appropriate process. If no, then it
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searches in global table, and is routed to the appropriate <TT>ejabberd</TT> node or
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process. If it does not exists in either tables, then it sent to the S2S
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manager.<BR>
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<BR>
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<!--TOC subsubsection Local Router-->
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<H4><A NAME="htoc4">1.1.2</A> Local Router</H4><!--SEC END -->
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This module routes packets which have a destination domain equal to this server
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name. If destination JID has a non-empty user part, then it routed to the
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session manager, else it is processed depending on it's content.<BR>
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<BR>
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<!--TOC subsubsection Session Manager-->
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<H4><A NAME="htoc5">1.1.3</A> Session Manager</H4><!--SEC END -->
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This module routes packets to local users. It searches for what user resource
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packet must be sended via presence table. If this resource is connected to
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this node, it is routed to C2S process, if it connected via another node, then
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the packet is sent to session manager on that node.<BR>
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<BR>
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<!--TOC subsubsection S2S Manager-->
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<H4><A NAME="htoc6">1.1.4</A> S2S Manager</H4><!--SEC END -->
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This module routes packets to other Jabber servers. First, it checks if an
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open S2S connection from the domain of the packet source to the domain of
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packet destination already exists. If it is open on another node, then it
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routes the packet to S2S manager on that node, if it is open on this node, then
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it is routed to the process that serves this connection, and if a connection
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does not exist, then it is opened and registered.<BR>
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<BR>
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<!--TOC section XML representation-->
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<H2><A NAME="htoc7">2</A> XML representation</H2><!--SEC END -->
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<A NAME="sec:xmlrepr"></A>
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Each XML stanza represented as following tuple:
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<PRE>
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XMLElement = {xmlelement, Name, Attrs, [ElementOrCDATA]}
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Name = string()
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Attrs = [Attr]
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Attr = {Key, Val}
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Key = string()
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Val = string()
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ElementOrCDATA = XMLElement | CDATA
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CDATA = {xmlcdata, string()}
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</PRE>E. g. this stanza:
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<PRE>
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<message to='test@conference.e.localhost' type='groupchat'>
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<body>test</body>
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</message>
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</PRE>represented as following structure:
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<PRE>
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{xmlelement, "message",
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[{"to", "test@conference.e.localhost"},
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{"type", "groupchat"}],
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[{xmlelement, "body",
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[],
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[{xmlcdata, "test"}]}]}}
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</PRE>
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<!--TOC section Module <TT>xml</TT>-->
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<H2><A NAME="htoc8">3</A> Module <TT>xml</TT></H2><!--SEC END -->
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<A NAME="sec:xmlmod"></A>
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<DL COMPACT=compact><DT>
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<CODE><B>element_to_string(El) -> string()</B></CODE><DD>
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<PRE>
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El = XMLElement
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</PRE>Returns string representation of XML stanza <TT>El</TT>.<BR>
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<BR>
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<DT><CODE><B>crypt(S) -> string()</B></CODE><DD>
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<PRE>
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S = string()
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</PRE>Returns string which correspond to <TT>S</TT> with encoded XML special
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characters.<BR>
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<BR>
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<DT><CODE><B>remove_cdata(ECList) -> EList</B></CODE><DD>
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<PRE>
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ECList = [ElementOrCDATA]
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EList = [XMLElement]
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</PRE><TT>EList</TT> is a list of all non-CDATA elements of ECList.<BR>
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<BR>
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<DT><CODE><B>get_path_s(El, Path) -> Res</B></CODE><DD>
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<PRE>
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El = XMLElement
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Path = [PathItem]
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PathItem = PathElem | PathAttr | PathCDATA
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PathElem = {elem, Name}
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PathAttr = {attr, Name}
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PathCDATA = cdata
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Name = string()
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Res = string() | XMLElement
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</PRE>If <TT>Path</TT> is empty, then returns <TT>El</TT>. Else sequentially
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consider elements of <TT>Path</TT>. Each element is one of:
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<DL COMPACT=compact><DT>
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<CODE><B>{elem, Name}</B></CODE><DD> <TT>Name</TT> is name of subelement of
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<TT>El</TT>, if such element exists, then this element considered in
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following steps, else returns empty string.
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<DT><CODE><B>{attr, Name}</B></CODE><DD> If <TT>El</TT> have attribute <TT>Name</TT>, then
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returns value of this attribute, else returns empty string.
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<DT><CODE><B>cdata</B></CODE><DD> Returns CDATA of <TT>El</TT>.
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</DL><BR>
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<BR>
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<DT><B>TODO:</B><DD>
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<PRE>
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get_cdata/1, get_tag_cdata/1
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get_attr/2, get_attr_s/2
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get_tag_attr/2, get_tag_attr_s/2
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get_subtag/2
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</PRE></DL>
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<!--TOC section <TT>ejabberd</TT> modules-->
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<H2><A NAME="htoc9">4</A> <TT>ejabberd</TT> modules</H2><!--SEC END -->
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<A NAME="sec:emods"></A>
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<!--TOC subsection <CODE>gen_mod</CODE> behaviour-->
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<H3><A NAME="htoc10">4.1</A> <CODE>gen_mod</CODE> behaviour</H3><!--SEC END -->
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<A NAME="sec:genmod"></A>
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TBD<BR>
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<BR>
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<!--TOC subsection Module <CODE>gen_iq_handler</CODE>-->
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<H3><A NAME="htoc11">4.2</A> Module <CODE>gen_iq_handler</CODE></H3><!--SEC END -->
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<A NAME="sec:geniqhandl"></A>
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The module <CODE>gen_iq_handler</CODE> allows to easily write handlers for IQ packets
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of particular XML namespaces that addressed to server or to users bare JIDs.<BR>
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<BR>
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In this module the following functions are defined:
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<DL COMPACT=compact><DT>
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<CODE><B>add_iq_handler(Component, NS, Module, Function, Type)</B></CODE><DD>
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<PRE>
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Component = Module = Function = atom()
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NS = string()
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Type = no_queue | one_queue | parallel
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</PRE>Registers function <CODE>Module:Function</CODE> as handler for IQ packets that
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contain child of namespace <CODE>NS</CODE> in <CODE>Component</CODE>. Queueing
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discipline is <CODE>Type</CODE>. There are at least two components defined:
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<DL COMPACT=compact><DT>
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<CODE><B>ejabberd_local</B></CODE><DD> Handles packets that addressed to server JID;
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<DT><CODE><B>ejabberd_sm</B></CODE><DD> Handles packets that addressed to users bare JIDs.
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</DL>
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<DT><CODE><B>remove_iq_handler(Component, NS)</B></CODE><DD>
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<PRE>
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Component = atom()
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NS = string()
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</PRE>Removes IQ handler for namespace <CODE>NS</CODE> from <CODE>Component</CODE>.
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</DL>
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Handler function must have the following type:
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<DL COMPACT=compact><DT>
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<CODE><B>Module:Function(From, To, IQ)</B></CODE><DD>
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<PRE>
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From = To = jid()
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</PRE></DL>
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<PRE>
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-module(mod_cputime).
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-behaviour(gen_mod).
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-export([start/1,
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stop/0,
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process_local_iq/3]).
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-include("ejabberd.hrl").
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-include("jlib.hrl").
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-define(NS_CPUTIME, "ejabberd:cputime").
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start(Opts) ->
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IQDisc = gen_mod:get_opt(iqdisc, Opts, one_queue),
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gen_iq_handler:add_iq_handler(ejabberd_local, ?NS_CPUTIME,
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?MODULE, process_local_iq, IQDisc).
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stop() ->
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gen_iq_handler:remove_iq_handler(ejabberd_local, ?NS_CPUTIME).
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process_local_iq(From, To, {iq, ID, Type, XMLNS, SubEl}) ->
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case Type of
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set ->
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{iq, ID, error, XMLNS,
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[SubEl, ?ERR_NOT_ALLOWED]};
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get ->
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CPUTime = element(1, erlang:statistics(runtime))/1000,
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SCPUTime = lists:flatten(io_lib:format("~.3f", CPUTime)),
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{iq, ID, result, XMLNS,
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[{xmlelement, "query",
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[{"xmlns", ?NS_CPUTIME}],
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[{xmlelement, "cputime", [], [{xmlcdata, SCPUTime}]}]}]}
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end.
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</PRE>
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<!--TOC subsection Services-->
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<H3><A NAME="htoc12">4.3</A> Services</H3><!--SEC END -->
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<A NAME="sec:services"></A>
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TBD<BR>
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<BR>
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TODO: use <CODE>proc_lib</CODE>
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<PRE>
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-module(mod_echo).
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-behaviour(gen_mod).
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-export([start/1, init/1, stop/0]).
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-include("ejabberd.hrl").
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-include("jlib.hrl").
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start(Opts) ->
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Host = gen_mod:get_opt(host, Opts, "echo." ++ ?MYNAME),
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register(ejabberd_mod_echo, spawn(?MODULE, init, [Host])).
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init(Host) ->
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ejabberd_router:register_local_route(Host),
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loop(Host).
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loop(Host) ->
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receive
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{route, From, To, Packet} ->
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ejabberd_router:route(To, From, Packet),
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loop(Host);
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stop ->
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ejabberd_router:unregister_local_route(Host),
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ok;
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_ ->
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loop(Host)
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end.
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stop() ->
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ejabberd_mod_echo ! stop,
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ok.
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</PRE>
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<BLOCKQUOTE><EM>This document was translated from L<sup>A</sup>T<sub>E</sub>X by
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</EM><A HREF="http://pauillac.inria.fr/~maranget/hevea/index.html"><EM>H<FONT SIZE=2><sup>E</sup></FONT>V<FONT SIZE=2><sup>E</sup></FONT>A</EM></A><EM>.
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