Java Reference
In-Depth Information
Understanding BPEL Process Basics
Problem
You want to see a simple BPEL process to get an overview of how to create composite service
orchestrations, without getting in too much detail.
Solution
If you deployed the Apache ODE Hello World example in the previous recipe, navigate to
the $TOMCAT_HOME/webapps/ode/WEB-INF/processes/HelloWorld2folder and open the
HelloWorld2.bpelfile with a text editor.
Discussion
Here's a quick overview of the sorts of things you can do with BPEL to give you an idea of
the scope of the language:
▪ Receive a client request message with <receive> .
▪ Invoke other web services within the composition using <invoke> .
▪ Send a response back to invoking clients using <reply> .
▪ Copy data from part of one message or variable into another using <assign> .
▪ Represent exceptions and handle them using <throw> , <catch> , and <catchAll> .
▪ Implement conditional logic using <switch> , <if> , <else> , and <pick> .
▪ Loop using <while> .
▪ Perform a step in the process after a duration or on a certain date and time using <wait> .
There are a variety of other constructs to help you create robust workflows in BPEL, but these
are the basic items that you'll use most frequently.
In the last recipe, you deployed the Hello World example that ships with the Apache ODE
BPEL engine. Let's open the file to see that there really isn't any magic to putting these puzzle
pieces together.
Other than the standard Apache license, Example 9-1 shows the complete, portable Hel-
loWorld2 process file.
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