spring-integration/src/reference/docbook/xmpp.xml

<?xml version="1.0" encoding="UTF-8"?>
<chapter xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="xmpp"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>XMPP Support</title>
  <para>
    Spring Integration provides Channel Adapters for <ulink url="http://www.xmpp.org">XMPP</ulink>.
  </para>
  <section id="xmpp-intro">
    <title>Introduction</title>
    <para>
      XMPP describes a way for multiple agents to communicate with each other in a distributed system.
      The canonical use case is to send and receive chat messages, though XMPP can be, and is, used for far more
      applications.
      XMPP is used to describe a network of actors. Within that network, actors may address each other directly, as well
      as broadcast status changes (e.g. "presence").
    </para>
    <para>
      XMPP provides the messaging fabric that underlies some of the biggest Instant Messaging networks in the world,
      including Google Talk (GTalk) - which is also available from within GMail - and Facebook Chat.
      There are many good open-source XMPP servers available. Two popular implementations are
      <ulink url="http://www.igniterealtime.org/projects/openfire/">
        <citetitle>Openfire</citetitle>
      </ulink>
      and
      <ulink url="http://www.ejabberd.im">
        <citetitle>ejabberd</citetitle>
      </ulink>
    </para>
    <para>
    Spring integration provides support for XMPP via XMPP adapters which support sending and receiving both XMPP chat messages and
    presence changes from other entries in your roster. As with other adapters, the XMPP adapters come with support for a
    convenient namespace-based configuration.
    To configure the XMPP namespace, include the following elements in the headers of your XML configuration file:

    <programlisting language="xml"><![CDATA[xmlns:int-xmpp="http://www.springframework.org/schema/integration/xmpp"
xsi:schemaLocation="http://www.springframework.org/schema/integration/xmpp
	http://www.springframework.org/schema/integration/xmpp/spring-integration-xmpp.xsd"]]></programlisting>

    </para>
  </section>

  <section id="xmpp-connection">
    <title>XMPP Connection</title>
    <para>
    Before using inbound or outbound XMPP adapters to participate in the XMPP network, an actor must establish its XMPP connection. This
	connection object could be shared by all XMPP adapters connected to a particular account. Typically this requires - at a minimum -
      <code>user</code>, <code>password</code>, and <code>host</code>.

      To create a basic XMPP connection, you can utilize the convenience of the namespace.
	</para>
    <programlisting language="xml"><![CDATA[<int-xmpp:xmpp-connection
    id="myConnection"
    user="user"
    password="password"
    host="host"
    port="port"
    resource="theNameOfTheResource"
    subscription-mode="accept_all"/>]]></programlisting>

    <para>
    	<note>
    	For added convenience you can rely on the default naming convention and omit the <code>id</code> attribute.
    	The default name <emphasis>xmppConnection</emphasis> will be used for this connection bean.
    	</note>
    </para>
    <para>
    If the XMPP Connection goes stale, reconnection attempts will be made with an automatic login as long as the previous connection
    state was logged (authenticated). We also register a <classname>ConnectionListener</classname> which will log connection events
    if the DEBUG logging level is enabled.
    </para>
  </section>

  <section id="xmpp-messages">
    <title>XMPP Messages</title>
    <section id="xmpp-message-inbound-channel-adapter">
      <title>Inbound Message Channel Adapter</title>
      <para>The Spring Integration adapters support receiving chat messages from other users in the system. To do this, the
        <emphasis>Inbound Message Channel Adapter</emphasis> "logs in" as a user on your behalf and receives the messages sent to that user. Those messages are then
        forwarded to your Spring Integration client.
        The payload of the inbound Spring Integration message may be of the raw type<classname>
          org.jivesoftware.smack.packet.Message</classname>, or of the type
        <classname>java.lang.String</classname> if you set the <code>extract-payload</code> attribute's value to 'true'
        when configuring an adapter.
        Configuration support for the XMPP <emphasis>Inbound Message Channel Adapter</emphasis> is provided via the <code>inbound-channel-adapter</code> element.

        <programlisting language="xml"><![CDATA[<int-xmpp:inbound-channel-adapter id="xmppInboundAdapter"
	channel="xmppInbound"
	xmpp-connection="testConnection"
	extract-payload="false"
	auto-startup="true"/>]]></programlisting>

	As you can see amongst the usual attributes this adapter also requires a reference to an XMPP Connection.
      </para>
      <para>
       It is also important to mention that the XMPP inbound adapter is an <emphasis>event driven adapter</emphasis>
       and a <classname>Lifecycle</classname> implementation.
       When started it will register a <classname>PacketListener</classname> that will listen for incoming XMPP Chat Messages.
       It forwards any received messages to the underlying adapter which will convert them to Spring Integration Messages and
       send them to the specified <classname>channel</classname>. It will unregister the <classname>PacketListener</classname>
       when it is stopped.
      </para>
    </section>


    <section id="xmpp-message-outbound-channel-adapter">
      <title>Outbound Message Channel Adapter</title>

     <para>
     	You may also send chat messages to other users on XMPP using the <emphasis>Outbound Message Channel Adapter</emphasis>.
     	Configuration support for the XMPP <emphasis>Outbound Message Channel Adapter</emphasis> is provided via the <code>outbound-channel-adapter</code> element.

     	<programlisting language="xml"><![CDATA[<int-xmpp:outbound-channel-adapter id="outboundEventAdapter"
						channel="outboundEventChannel"
						xmpp-connection="testConnection"/>]]></programlisting>

		The adapter expects as its input - at a minimum - a payload of type <classname>java.lang.String</classname>, and a header value
		for <classname>XmppHeaders.CHAT_TO</classname> that specifies to which user the Message should be sent.
		To create a message you might use the following Java code:

		<programlisting language="java"><![CDATA[Message<String> xmppOutboundMsg = MessageBuilder.withPayload("Hello, XMPP!" )
						.setHeader(XmppHeaders.CHAT_TO, "userhandle")
						.build();]]></programlisting>

		Another mechanism of setting the header is by using the XMPP header-enricher support. Here is an example.

		<programlisting language="xml"><![CDATA[<int-xmpp:header-enricher input-channel="input" output-channel="output">
	<int-xmpp:chat-to value="test1@example.org"/>
</int-xmpp:header-enricher>]]></programlisting>
     </para>
    </section>
  </section>


  <section id="xmpp-presence">
    <title>XMPP Presence</title>

        <para>
        XMPP also supports broadcasting state. You can use this capability to
        let people who have you on their roster see your state changes. This happens all the time with your IM clients; you
        change your away status, and then set an away message, and everybody who has you on their roster sees your icon or username
        change to reflect this new state, and additionally might see your new "away" message.
        If you would like to receive notification, or notify others, of state changes, you can use Spring Integration's "presence" adapters.
       </para>

    <section id="xmpp-roster-inbound-channel-adapter">
      <title>Inbound Presence Message Channel Adapter</title>
    <para>
      Spring Integration provides an <emphasis>Inbound Presence Message Channel Adapter</emphasis> which supports receiving Presence
      events from other users in the system who happen to be on your Roster. To do this, the adapter "logs in" as a user
      on your behalf, registers a <classname>RosterListener</classname> and forwards received Presence update events as Messages to the channel
      identified by the <code>channel</code> attribute. The payload of the Message will be a <classname>org.jivesoftware.smack.packet.Presence</classname>
	  object (see http://www.igniterealtime.org/builds/smack/docs/3.1.0/javadoc/org/jivesoftware/smack/packet/Presence.html).
    </para>
    <para>
    Configuration support for the XMPP <emphasis>Inbound Presence Message Channel Adapter</emphasis> is provided via
    the <code>presence-inbound-channel-adapter</code> element.
 <programlisting language="xml"><![CDATA[<int-xmpp:presence-inbound-channel-adapter channel="outChannel"
		xmpp-connection="testConnection" auto-startup="false"/>]]></programlisting>

	  As you can see amongst the usual attributes this adapter also requires a reference to an XMPP Connection.
	  It is also important to mention that this adapter is an event driven adapter and a <classname>Lifecycle</classname> implementation.
	  It will register a <classname>RosterListener</classname> when started and will unregister that <classname>RosterListener</classname>
	  when stopped.
    </para>
    </section>

    <section id="xmpp-roster-outbound-channel-adapter">
      <title>Outbound Presence Message Channel Adapter</title>

      <para>
      Spring Integration also supports sending Presence events to be seen by other users in the network who happen to have you on their
      Roster. When you send a Message to the <emphasis>Outbound Presence Message Channel Adapter</emphasis> it extracts the payload,
      which is expected to be of type <classname>org.jivesoftware.smack.packet.Presence</classname>
	  (see http://www.igniterealtime.org/builds/smack/docs/3.1.0/javadoc/org/jivesoftware/smack/packet/Presence.html) and sends it to
	  the XMPP Connection, thus advertising your presence events to the rest of the network.
      </para>
      <para>
      Configuration support for the XMPP <emphasis>Outbound Presence Message Channel Adapter</emphasis> is provided via
      the <code>presence-outbound-channel-adapter</code> element.

      <programlisting language="xml"><![CDATA[<int-xmpp:presence-outbound-channel-adapter id="eventOutboundPresenceChannel"
	xmpp-connection="testConnection"/>]]></programlisting>

	  It can also be a <emphasis>Polling Consumer</emphasis> (if it receives Messages from a Pollable Channel) in which case you would
	  need to register a Poller.

	  <programlisting language="xml"><![CDATA[<int-xmpp:presence-outbound-channel-adapter id="pollingOutboundPresenceAdapter"
		xmpp-connection="testConnection"
		channel="pollingChannel">
	<int:poller fixed-rate="1000" max-messages-per-poll="1"/>
</int-xmpp:presence-outbound-channel-adapter>]]></programlisting>

	Like its inbound counterpart, it requires a reference to an XMPP Connection.
      </para>
    </section>
    <para>
    	<note>
		If you are relying on the default naming convention for an XMPP Connection bean (described earlier), and you have only one
		XMPP Connection bean configured in your Application Context, you may omit the <code>xmpp-connection</code> attribute.
		In that case, the bean with the name <emphasis>xmppConnection</emphasis> will be located and injected into the adapter.
    	</note>
    </para>
  </section>
  <section id="xmpp-advanced">
		<title>Advanced Configuration</title>

    	<para>
    	Since Spring Integration XMPP support is based on the Smack 3.1 API (http://www.igniterealtime.org/downloads/index.jsp), it is important
    	to know a few details related to more complex configuration of the XMPP Connection object.
    	</para>
    	<para>
    	As stated earlier the <code>xmpp-connection</code> namespace support is designed to simplify basic connection configuration and
    	only supports a few common configuration attributes. However, the <classname>org.jivesoftware.smack.ConnectionConfiguration</classname>
        object defines about 20 attributes, and there is no real value of adding namespace support for all of them. So, for more complex connection
        configurations, simply configure an instance of our <classname>XmppConnectionFactoryBean</classname> as a regular bean, and inject a
    	<classname>org.jivesoftware.smack.ConnectionConfiguration</classname> as a constructor argument to that FactoryBean. Every property
    	you need, can be specified directly on that ConnectionConfiguration instance (a bean definition with the 'p' namespace would work well).
        This way SSL, or any other attributes, could be set directly. Here's an example:

        <programlisting language="xml"><![CDATA[<bean id="xmppConnection" class="o.s.i.xmpp.XmppConnectionFactoryBean">
    <constructor-arg>
        <bean class="org.jivesoftware.smack.ConnectionConfiguration">
            <constructor-arg value="myServiceName"/>
            <property name="truststorePath" value="..."/>
            <property name="socketFactory" ref="..."/>
        </bean>
    </constructor-arg>
</bean>
<int:channel id="outboundEventChannel"/>

<int-xmpp:outbound-channel-adapter id="outboundEventAdapter"
    channel="outboundEventChannel"
    xmpp-connection="xmppConnection"/>]]></programlisting>
    	</para>
    <para>
    Another important aspect of the Smack API is static initializers. For more complex cases (e.g., registering a SASL Mechanism), you may need
    to execute certain static initializers. One of those static initializers is <classname>SASLAuthentication</classname>, which allows
    you to register supported SASL mechanisms. For that level of complexity, we would recommend Spring JavaConfig-style of the XMPP Connection
    configuration. Then, you can configure the entire component through Java code and execute all other necessary Java code including
    static initializers at the appropriate time.

    <programlisting language="java"><![CDATA[@Configuration
public class CustomConnectionConfiguration {
  @Bean
  public XMPPConnection xmppConnection() {
	SASLAuthentication.supportSASLMechanism("EXTERNAL", 0); // static initializer

	ConnectionConfiguration config = new ConnectionConfiguration("localhost", 5223);
	config.setTrustorePath("path_to_truststore.jks");
	config.setSecurityEnabled(true);
	config.setSocketFactory(SSLSocketFactory.getDefault());
	return new XMPPConnection(config);
  }
}]]></programlisting>
	For more information on the JavaConfig style of Application Context configuration, refer to the following section in the Spring Reference Manual:
	http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/beans.html#beans-java
    </para>
    </section>

</chapter>