Red Hat
Feb 1, 2014
by Maciej Swiderski
After release of 6.0 of jBPM, there were number of questions coming from community about how processes can be deployed into the new and shiny jbpm console?

So let's start with short recap on how the deployment model look like in jBPM 6. In version 5.x processes were stored in so called packages produced by Guvnor and next downloaded by jbpm console for execution using KnowledgeAgent. Alternatively one could drop their process files (bpmn2 files) into a predefined directory that was scanned on the jbpm console start. That was it.

That enforces users to always use Guvnor when dynamic deployment was needed. Although there is nothing wrong with it, actually that was recommended approach but not everyone was happy with that setup.

Version 6, on the other hand moves away from proprietary packages in favor of, well known and mature, Apache Maven based packaging - known as knowledge archives - kjar. What does that mean? First of all, processes, rules etc (aka business assets) are now part of a simple jar file built and managed by Maven. Along the business assets, java classes and other file types are stored in the jar file too. Moreover, as any other maven artifact, kjar can have defined dependencies on other artifacts including other kjars.
What makes the kjar special when compared with regular jars? It is a single descriptor file kept inside META-INF directory of the kjar - kmodule.xml. That descriptor allows to define:

  • knowledge bases and their properties
  • knowledge sessions and their properties
  • work item handlers
  • event listeners
By default, this descriptor is empty (just kmodule root element) and is considered as marker file. Whenever a runtime component (such as jbpm console) is about to process kjar it looks up kmodule.xml to build its runtime representation. See documentation for more details about kmodule.xml and kjars.

Alright, now we know bit more about what is actually placed on runtime environment - kjar. So how we can deploy kjar into running jbpm console? There are several ways:

Design and build your kjar inside jbpm console

The easiest way is to actually use jbpm console to completely build the kjar. For that purpose there is entire perspective available - Authoring perspective - that consist of quite big set of editors tailored for various asset types.

First, you have to have repository created where your projects (after they are built they become kjars) will be stored. When running the demo setup of jbpm console (installed by jbpm installer), you will have two repositories already available - jbpm-playground and uf-playground. You can use any of these or create new repository.
Once you have repository available, create new item - a project - you need to specify GAV (GroupId, ArtifactId, Version) to name your project.
Next you create business assets in it, like business processes, rules, data model, forms, etc. And now we are at the stage where we should build and deploy our project into runtime. Nothing simpler than that - just press "Build & Deploy" button and you're ready to rock!

Is that really that simple?! In most of the cases, yes, it is really that simple. But you need to be aware of several rules (convention over configuration) that drive the build and deploy. First rule is that everything needs to be properly designed - processes, rules, etc - that is the build phase that catches any compilation or validation errors and provides feedback to the user via Problems Panel.
Assuming, all assets are built successfully, the deploy phase comes into the picture. Deploy phase is actually a two step process:
  • Maven phase - 
    • it installs build project (now it's kjar already) into Maven local repository (usually ~/.m2/repository but it can be configured with standard maven way - settings.xml)
    • deploys built project into jbpm console embedded Maven repository - it's a remote repository accessible over http and can be declared in pom.xml, settings.xml as any other maven repository
  • Runtime phase
    • once Maven phase is completed successfully, jbpm console will attempt to deploy the kjar into runtime environment for execution. Here are few requirements to make this happen:
      • kmodule.xml needs to be empty - which it is by default unless you edited it via Project Editor
      • kmodule.xml must have at least one knowledge base and stateful knowledge session defined and marked as default
When both phases are successfully completed, your kjar is deployed to runtime environment and ready for execution. Simply go to Process Management --> Process Definitions to examine what's there and start executing your just deployed processes.

So that's first and the easiest way to get started with deployments in jBPM 6.

Build project in IDE and push to console for build and deploy

Another approach would be when you prefer to do the heavy work in your IDE like Eclipse (since the modeling capabilities - bpmn2 modeler - is only available in Eclipse).  So you do pretty much similar steps, although no need to create repository here but clone an existing one from jbpm console instead.  So you first start with cloning of an existing repository. 

git clone ssh://{jbpmconsole-host}:{port}/{repository-name}

Then create Maven project - you can actually do that with jBPM Project wizard in eclipse, that creates simple Maven project with sample business process and executable class in it to get you started much faster. 

Note: make sure you place the project in the cloned repository structure so it can be later on pushed back.

It declares dependencies to jbpm-test module to be able to execute the sample process.
Once you have a mavenized project, you're ready to start working on your business assets, data model and more. 
When done, you're ready to push your project into jbpm console so it can be built and deployed to runtime environment. To do so, you need to use any GIT tool that allows you to pull and push changes from your working copy into the master repository. To add all files in your working copy into commit index:

git add -A

then examine if you haven't added too much like the target folder, if so create or edit .gitignore file to exclude unneeded files. And commit:

git commit -m "my first jbpm project"

once committed, push it to origin

git push origin master

now go into jbpm console Authoring perspective, and you should see you project in the repository, it's ready to be build and deployed. Just follow same step from the first approach to build and deploy it. 
That was second approach to deploying business assets into jbpm console version 6. Somehow in between developers and business users. Might also be seen as collaboration way - where initially business users create high level processes, rules etc and then developers step in and add implementation details and some "glue code" to make it fully executable.

Build and deploy to Maven from IDE

This one focuses completely on developers and allows to actually do the work without being too much aware of jbpm console. So here developers build regular maven projects that include business assets, java classes, forms and then add the kmodule.xml to make the jar become kjar. Everything is done in IDE of developer choice. Same goes for version control system, it does not have to be git any more, in this case. That is because, jbpm console won't be used as source management tool for these projects but it will be used only for pure execution capabilities.

Once you're done with development, you simply build the project with maven (mvm clean install). That makes it directly available for any other components that would like to use it on your local machine. So if you're running jbpm console on your machine you can directly skip to section deployment (three paragraphs below ;))

When jbpm console is running on remote host, you have two ways to make it aware of your artifacts built externally:
  • deploy (using maven) your projects into jbpm console Maven repository - as this is like any other repository you can use maven deploy goal after you have defined that repository either in your pom.xml or settings.xml
  • make jbpm console maven installation aware of any external maven repositories it should consider while deploying kjars
The first one, deploy to maven repository, does not have anything special, it's as simple as defining the repository in settings.xml so it can be successfully contacted and the artifact can be stored when running mvm clean install deploy.
Then the second approach is again standard maven way. On the machine (and user) that jbpm console is running, you need to add your main maven repository into settings.xml so whenever jbpm console will attempt to deploy the kjar it will look up for it in your maven repository.

With all these steps, jbpm console is now capable of finding the kjars that are outside of it's local maven repository so it can download them when needed. You can now go to jbpm console Deploy --> Deployments perspective where you can add new deployment units manually.
It's as simple as providing GAV of the project you want to deploy and optionally knowledge base and knowledge session names if you defined more than what is there by default.
In addition to that, you can select runtime strategy that fits your requirements for that given kjar - chose one from Singleton, Per Request or Per Process instance.

That concludes deployment options available in jBPM version 6. It promotes well known standards defined by maven and allow various ways of integrating with the jbpm console functionality. You, as a user, are in the control how you work with the tooling where you can leverage it's full power to do everything over the web, integrate with GIT server, to do everything externally and use it only for execution.

Hope that puts some light on the way you can use jBPM 6 out of the box and empowers your day to day work. As usual, ending with the same sentence: all comments and ideas are more than welcome.