Java Reference
In-Depth Information
. . . . .
}
Using JMS to integrate with external systems
At the beginning of this chapter, we have mentioned that the JCA Adaptor handles
the communication between the application server and the HornetQ server.
As a matter of fact, one possible way to perform
Enterprise Application Integration
(EAI)
is via
Java Connector Architecture
(
JCA
), which can be used to drive JMS
inbound and outbound connections.
Initially, Java connectors were intended to access legacy transaction servers on
mainframes in a synchronous request/reply mode, and this is how the majority of the
connectors worked in the beginning. The standard is currently evolving toward more
asynchronous and two-way connectivity; this is exactly the case of JMS communic-
ation, which is inherently asynchronous (but also offers the capability of simulating
a synchronous request/response mode). In the next section we will show you how
to use a Java Resource Adapter to enable communication between JBoss' HornetQ
Messaging system and Apache ActiveMQ integrated with Apache Geronimo.
Tip
JMS/JCA integration versus web services
If we are discussing EAI we cannot help but talk about the difference with web
services, which is a de facto standard for integrating heterogeneous systems.
One advantage of using JMS/JCA integration is that it provides support for re-
source adaptation, which maps the Java EE security, transaction, and commu-
nication pooling to the corresponding EIS technology. This makes this technology
fairly attractive especially if you are connecting some existing, well-consolidated,
and homogeneous systems. (Remember that if you are using JMS as the driver,
you are bound to Java-to-Java interaction).
