here is also a student :-)
jbpm and bpel are process definition languages.
You can modell something like this:
First you have to connect to the database
Secondly you have to logon to the database
Thirdly you can start a select operation
Lastly you have to logoff and disconnect the database
You can write this in a jbpm-processdefinition or in a BPEL-Processdefinition. Both say exactly the workflow of you operation. Yaou cannot logon to database without a connect. In this example it is a technical requirement but it's not a necessity.
Both will do the same (like C and Cobol :-) ) but have different aims:
jbpm is used simply for orchestrating of processes
bpel is the big brother for internetoperations.
If you look in the docu to bpel of jboss:
2.5. Which one is for me?
Introduction to jBPM BPEL
Some business processes involve frequent interactions with heterogeneous systems or partners. In these cases interoperability
is essential, and XML is the obvious data transfer format. If you run into a similar scenario, we encourage
you to choose BPEL. Manipulating XML documents with Java or any other non-XML language is tedious,
verbose and error-prone. BPEL alleviates much of this pain through the following features:
? message exchange with efficiency (no Java/XML binding) and type safety (automatic format checking)
? comfortable message content manipulation (XPath 1.0 expressions)
? asynchronous message reception
? encapsulation of the underlying web services machinery
If this is not your case and you are mostly coordinating Java components, use jPDL. You'll find it easier to use and
you will be able to model practically any imaginable scenario by leveraging jBPM's workflow-rich features.
Hope this helps