This document discusses jBPM4 container integration with application servers, specifically deployment and undeployment of processes on JBoss AS. It describes how processes are versioned and stored in the database, and that redeployment is not idempotent. It outlines the approaches of using versions or timestamps for identifying deployments and different deployment scenarios. It also discusses the process lifecycle and classloading issues that can occur during undeployment or if artifacts are removed while the server is shutdown. The status and next steps covered are implementing on JBoss AS 4.2.x, JNDI bindings, and relationship to the 'enterprise' module.

1. jBPM4 container
integration: Deployer
Heiko Braun <hbraun@redhat.com>
09.03.2009

2. Overview
• Process deployment specifics
• Concepts and gotchas with deployment/
undeployment
• Status and next steps

3. AS deployments
• Create a *.par archive and copy it to
server/<config>/deploy
• Can be done while AS running or when it’s
shutdown
• Covered by the AS deployer API

4. Process deployment:
BPM specifics
• In BPM we expect long running processes
• i.e. exists across AS reboots
• Processes are versioned:
• Deployment can lead to a new version
or “replace” a prior one (aka patching)
• Process model is actually a database model:
• Redeployment is not idempotent [1]
[1] “Acting as if used only once, even if used multiple times. “

5. Deployment
• Two approaches: Version or
timestamp identification
• Version: Explicit as part of
the process definition
(*.jpdl.xml)
• Timestamp: Implicit, refers
to the actual deployment
artifact (filesystem)
• Applies to the same deployment
artifact (filename)
• Derived policy identifies
processes that will be stored in
DB

6. Deployment scenarios
• Patching a process (i.e. replacing a class,
bugfix, etc):
- same artifact with same version
• Providing a new process (i.e. different pdl):
- same artifact different version, or no
version at all
• Otherwise: New artifact, new version

7. Undeployment
• Single approach: Does the
deployment artifact exist?
• Usally undeployment happens
when removing files from server/
<config>/deploy
• Exception: On server shutdown,
all deployer get undeployment
callbacks
• Only if the deployment artifact
is deleted the process will be
removed

8. Undeployment
scenarios
• Server shutdown
- retain process
• Artifact removed w. server running
- delete process
• Artifact removed with server stopped
- Not realized by process engine ?!

9. Process lifecycle and
classloader
• Server boot
- Associate classloader, flag process “ready”
• Server shutdown
- Remove classloader, flag process “shutdown”
• Gotcha: Artifact removed while server is shutdown
• upon boot only processes w. artifacts will be flagged
“ready”
• leaves non-usable (“shutdown”) processes that need to
be removed manually

10. Status
• Resides in ‘modules/integration’
• Implemented for AS 5
• No JNDI binding yet
• No classloader association
• Works as proof of concept

11. Next steps
• Port to AS 4.2.x
• Implement JNDI bindings
• Relationship to ‘enterprise’ module
• Extended in container test coverage

12. Q&A

13. Appendix:
Implemention on AS 5
• Deployment example
16:22:41,522 INFO [JBPMDeployer] Deploy JBPMDeploymentMetaData {unit=vfszip:/Users/hbraun/dev/prj/jboss/tags/JBoss_5_0_0_GA/build/
output/jboss-5.0.0.GA/server/default/deploy/Simple-Alpha2.jar/Simple_noversion.jpdl.xml, jpdl=vfszip:/Users/hbraun/dev/prj/jboss/tags/
JBoss_5_0_0_GA/build/output/jboss-5.0.0.GA/server/default/deploy/Simple-Alpha2.jar/Simple_noversion.jpdl.xml,
cl=BaseClassLoader@bc4d42{vfszip:/Users/hbraun/dev/prj/jboss/tags/JBoss_5_0_0_GA/build/output/jboss-5.0.0.GA/server/default/deploy/Simple-
Alpha2.jar}}
16:22:41,571 INFO [VersionTimestampPolicy] Timestamp driven policy evaluation: process 'Simple_noversion', timestamp 1236612157000
16:22:41,615 INFO [JBPMDeployer] Deploy JBPMDeploymentMetaData {unit=vfszip:/Users/hbraun/dev/prj/jboss/tags/JBoss_5_0_0_GA/build/
output/jboss-5.0.0.GA/server/default/deploy/Simple-Alpha2.jar/Simple_version.jpdl.xml, jpdl=vfszip:/Users/hbraun/dev/prj/jboss/tags/
JBoss_5_0_0_GA/build/output/jboss-5.0.0.GA/server/default/deploy/Simple-Alpha2.jar/Simple_version.jpdl.xml,
cl=BaseClassLoader@bc4d42{vfszip:/Users/hbraun/dev/prj/jboss/tags/JBoss_5_0_0_GA/build/output/jboss-5.0.0.GA/server/default/deploy/Simple-
Alpha2.jar}}
16:22:41,641 INFO [VersionTimestampPolicy] Version driven policy evaluation: process 'Simple_withversion', version 3

14. Appendix:
Implemention on AS 5
• Embracing EE5:
2009-03-09 15:26:22,737 INFO [org.jbpm.integration.jboss5.JBPMServiceImpl] (main) ProcessEngine bound to: java:/jbpm4
class myEJB {
[...]
try
{
InitialContext ctx = new InitialContext();
this.processEngine = (ProcessEngine)ctx.lookup(quot;java:/jbpm4quot;);
}
catch (Exception e)
{
throw new RuntimeException(quot;Failed to lookup process enginequot;);
}
}