docs/user-manual/modules/ROOT/pages/publish-subscribe-channel.adoc

[[PublishSubscribeChannel-PublishSubscribeChannel]]
= Publish Subscribe Channel

Camel supports the
http://www.enterpriseintegrationpatterns.com/PublishSubscribeChannel.html[Publish
Subscribe Channel] from the
xref:enterprise-integration-patterns.adoc[EIP patterns] using for
example the following components:

* xref:components::jms-component.adoc[JMS] for working with JMS Topics for high performance,
clustering and load balancing
* xref:components::xmpp-component.adoc[XMPP] when using rooms for group communication
* xref:components::seda-component.adoc[SEDA] for working with SEDA in the same
xref:camelcontext.adoc[CamelContext] which can work in pub-sub, but
allowing multiple consumers.
* xref:components::vm-component.adoc[VM] as SEDA but for intra-JVM.

image::eip/PublishSubscribeSolution.gif[image]

[[PublishSubscribeChannel-Samples]]
== Samples

Another option is to explicitly list the publish-subscribe relationship
in your routing logic; this keeps the producer and consumer decoupled
but lets you control the fine grained routing configuration using the
xref:dsl.adoc[DSL] or xref:xml-configuration.adoc[Xml Configuration].

In Java code:

[source,java]
----
from("direct:a")
    .multicast()
      .to("direct:b")
      .to("direct:c")
      .to("direct:d")
    .end() // end multicast
----

And in XML:

[source,xml]
----
<camelContext xmlns="http://camel.apache.org/schema/spring">
    <route>
        <from uri="direct:a"/>
        <multicast>
            <to uri="direct:b"/>
            <to uri="direct:c"/>
            <to uri="direct:d"/>
        </multicast>
    </route>
</camelContext>
----