mirror of
https://github.com/vanitasvitae/Smack.git
synced 2024-12-23 19:18:00 +01:00
bdd57b90f7
git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/trunk@2258 b35dd754-fafc-0310-a699-88a17e54d16e
121 lines
4.7 KiB
HTML
121 lines
4.7 KiB
HTML
<html>
|
|
<head>
|
|
<title>Smack: Provider Architecture - Jive Software</title>
|
|
<link rel="stylesheet" type="text/css" href="style.css" />
|
|
</head>
|
|
|
|
<body>
|
|
|
|
<div class="header">
|
|
Provider Architecture: Packet Extensions and Custom IQ's
|
|
</div>
|
|
|
|
<div class="nav">
|
|
« <a href="index.html">Table of Contents</a>
|
|
</div>
|
|
|
|
<p>
|
|
|
|
The Smack provider architecture is a system for plugging in
|
|
custom XML parsing of packet extensions and IQ packets. The
|
|
standard <a href="extensions/index.html">Smack Extensions</a>
|
|
are built using the provider architecture. Two types of
|
|
providers exist:<ul>
|
|
<li><tt>IQProvider</tt> -- parses IQ requests into Java objects.
|
|
<li><tt>PacketExtension</tt> -- parses XML sub-documents attached to
|
|
packets into PacketExtension instances.</ul>
|
|
|
|
<p class="subheader">IQProvider</p>
|
|
|
|
By default, Smack only knows how to process IQ packets with sub-packets that
|
|
are in a few namespaces such as:<ul>
|
|
<li>jabber:iq:auth
|
|
<li>jabber:iq:roster
|
|
<li>jabber:iq:register</ul>
|
|
|
|
Because many more IQ types are part of XMPP and its extensions, a pluggable IQ parsing
|
|
mechanism is provided. IQ providers are registered programatically or by creating a
|
|
smack.providers file in the META-INF directory of your JAR file. The file is an XML
|
|
document that contains one or more iqProvider entries, as in the following example:
|
|
|
|
<pre>
|
|
<?xml version="1.0"?>
|
|
<smackProviders>
|
|
<iqProvider>
|
|
<elementName>query</elementName>
|
|
<namespace>jabber:iq:time</namespace>
|
|
<className>org.jivesoftware.smack.packet.Time</className>
|
|
</iqProvider>
|
|
</smackProviders></pre>
|
|
|
|
Each IQ provider is associated with an element name and a namespace. In the
|
|
example above, the element name is <tt>query</tt> and the namespace is
|
|
<tt>abber:iq:time</tt>. If multiple provider entries attempt to register to
|
|
handle the same namespace, the first entry loaded from the classpath will
|
|
take precedence. <p>
|
|
|
|
The IQ provider class can either implement the IQProvider
|
|
interface, or extend the IQ class. In the former case, each IQProvider is
|
|
responsible for parsing the raw XML stream to create an IQ instance. In
|
|
the latter case, bean introspection is used to try to automatically set
|
|
properties of the IQ instance using the values found in the IQ packet XML.
|
|
For example, an XMPP time packet resembles the following:
|
|
|
|
<pre>
|
|
<iq type='result' to='joe@example.com' from='mary@example.com' id='time_1'>
|
|
<query xmlns='jabber:iq:time'>
|
|
<utc>20020910T17:58:35</utc>
|
|
<tz>MDT</tz>
|
|
<display>Tue Sep 10 12:58:35 2002</display>
|
|
</query>
|
|
</iq></pre>
|
|
|
|
In order for this packet to be automatically mapped to the Time object listed in the
|
|
providers file above, it must have the methods setUtc(String), setTz(String), and
|
|
setDisplay(String). The introspection service will automatically try to convert the String
|
|
value from the XML into a boolean, int, long, float, double, or Class depending on the
|
|
type the IQ instance expects.<p>
|
|
|
|
<p class="subheader">PacketExtensionProvider</p>
|
|
|
|
Packet extension providers provide a pluggable system for
|
|
packet extensions, which are child elements in a custom namespace
|
|
of IQ, message and presence packets.
|
|
Each extension provider is registered with an element name and namespace
|
|
in the smack.providers file as in the following example:
|
|
|
|
<pre>
|
|
<?xml version="1.0"?>
|
|
<smackProviders>
|
|
<extensionProvider>
|
|
<elementName>x</elementName>
|
|
<namespace>jabber:iq:event</namespace>
|
|
<className>org.jivesoftware.smack.packet.MessageEvent</className>
|
|
</extensionProvider>
|
|
</smackProviders></pre>
|
|
|
|
If multiple provider entries attempt to register to handle the same element
|
|
name and namespace, the first entry loaded from the classpath will take
|
|
precedence.<p>
|
|
|
|
Whenever a packet extension is found in a packet, parsing will
|
|
be passed to the correct provider. Each provider can either implement the
|
|
PacketExtensionProvider interface or be a standard Java Bean. In the
|
|
former case, each extension provider is responsible for parsing the raw
|
|
XML stream to contruct an object. In the latter case, bean introspection
|
|
is used to try to automatically set the properties of the class using
|
|
the values in the packet extension sub-element.<p>
|
|
|
|
When an extension provider is not registered for an element name and
|
|
namespace combination, Smack will store all top-level elements of the
|
|
sub-packet in DefaultPacketExtension object and then attach it to the packet.
|
|
|
|
|
|
<br clear="all" /><br><br>
|
|
|
|
<div class="footer">
|
|
Copyright © Jive Software 2002-2004
|
|
</div>
|
|
|
|
</body>
|
|
</html>
|