Hi Gert, the spi package is only applicable JBoss containers.
But the idea is simple: Create a service entity that can hold a reference to the process engine and bind a lookup mechanism to JNDI.
I am not a weblogic expert, but IIRC weblogic has "startup" classes that can be used for such purposes.
Alternatively you might look into packaging jbpm as an EAR.
I am doing a POC for a big company to use a Jbpm as workflow engine in order to migrate form Staffware tibco to Jbpm.
I made Jbpm works (jbpm 3.2.6) on weblogic AS 10.3 and oracle 10g database. But with this version I had to do some changes as described here: http://www.jboss.org/index.html?module=bb&op=viewtopic&t=157949
But, my boss doesn't like this because he wants to by support from Jboss.
Now, I want to deploy Jbpm 4.0 in the same environment because it seems more interesting than the other version.
Can you give me the URL of svn of this project and may be I can give you some helps