BPMN – BPEL and XPDL Editors

Over the years I have seen and used many different methods of diagramming business processes. Looking back at all my old diagrams, even something as standard as a hand-off swimlane diagram has taken on many different forms.

For this reason, I decided to dive deeper into BPMN (Business Process Markup Notation) and see if this standard can work for both the customer and the technical team. I was also curious about mapping processes for Service Oriented Architecture workflow implementations, and found that some of the BPMN based diagramming tools that write Execution Language in the background, are pretty cool. So I decided to evaluate a few of the open-source options out there and here’s what I came up with.

The first hurdle I had to get though was all the confusion that has been created between BPMN, BPEL and XPDL. First off, BPMN is a good effort regardless if one is implementing SOA or just diagramming their processes. The industry has long needed a standard for how business processes are diagrammed to help reduce the countless different methods out there. BPMN is a well thought out collection of symbols and rules for diagramming workflow.

XPDL and BPEL are a bit grayer. XPDL (eXtensible Process Diagramming Language) is a good idea because it creates a common XML schema for saving business process diagrams. As long as it is solely thought of as a business process diagram format, then everything is crystal clear (to me a least). It’s when a lengthy list of workflow engines start calling themselves “XPDL” compatible that it really gets confusing to me.

BPEL (Business Process Execution Language) is supposed to be the orchestration language that a workflow engine reads to execute the workflow, not XPDL. Yet some of the workflow engines are using XPDL as the executable orchestration language. Maybe its being parsed into BPEL, but I certainly don’t know and don’t care.

I’m just trying to determine if I should use a workflow editor that creates BPEL, like Intalio, or one that creates XPDL, like JaWE. It seems to me that XPDL is my best choice because I can read XPDL back into a diagramming tool much easier. My real confusion is that if I’m using an XPDL editor and an XPDL “compatible” workflow engine, then what do I care about BPEL? Jon Pyke, chairman of the Workflow Management Coalition (WfMC) says in one of his articles that BPEL and XPDL are not competing technologies, rather they are complimentary but if my XPDL can be used in a “XPDL compatible” workflow engine then it seems to me that they are competing.

Okay, enough venting, I’m sure that someone with more knowledge on the topic than I can set me straight.

On with my evaluation

The first editor and workflow engine combination that I looked at was the Intalio suite. The editor is a plugin for the Eclipse development environment and is pretty good. It’s open-source although there is the shrink-wrapped version that can be purchased from Intalio. I really liked the fact that the diagramming symbols and rules followed the BPMN specifications to the T. I also liked that it was a no-brainer to have it up and running. The one thing that seems a bit out of the standard though, goes back to my earlier rant about XPDL vs. BPEL. The Intalio diagramming editor saves the diagrams as BPEL, which is fine if all I want to do is execute the workflow on a BPEL engine but it seems to me that XPDL should be the standard for saving diagrams.

The next combination that I installed and played with was the Together Workflow Editor, based on the open-source JaWE editor. Unlike Intalio, this editor saves the diagrams as XPDL according to the WfMC. To my disappointment, however, the diagramming symbols were not complete, according to BPMN standards. The attributes can all be stored in the task and transition symbols, but the pool/Swimlane paradigm is missing and I couldn’t find any gateway symbols anywhere. The Shark® workflow engine was also disappointing in that the supposedly open-source version (not the demo) had a very annoying splash screen, which means the source code would need to be modified and recompiled. So much for a quick (no-brainer) installation like Intalio.

Another JaWE based editor that I looked at, was jPed, which wasn’t much different than the TWE version, except that I did find a gateway symbol.

JBoss and the jBPM editor were the next on the list. This editor was every bit as good as the Intalio editor. It contains all the BPMN specification symbols and rules. The non-standard part of the mix is that the jBPM editor saves the diagrams as jPDL, which is similar to XPDL but more Java centric. This makes sense because the project’s scope was to create a tool that supplements a Java project so it was never intended to follow the WfMC standards. Still, not a bad editor and JBoss is pretty easy to get up and running. Of course actually implementing a solution with any of these examples would be a major project and I don’t mean to make it sound like its not.

I tried to install Bonita, which is a Java based, open-source, editor that runs on the JOnAS application server. Looking through the documentation, this looks like an excellent project, however, I tried three times, on two different machines, to download and install JOnAS and the file was corrupt every time. I guess I’ll have to compile the source but I haven’t had the opportunity yet.

Some of the other projects I looked into were BPeX, XPDL Visual Editor, BxModeller and Nezha. BPeX and XPDL Visual Editor are apparently in the early stages and don’t have a release yet. BxModeller, I must admit, I haven’t had a chance to install it yet. It looks like a worthy project though and I’m looking forward to reviewing it.

Nezha is another Eclipse plugin and it may just be my unfamiliarity with Eclipse but I couldn’t get the plugin to load. I haven’t given up though, so hang in there.

Bye,

Dave

Tags: BPEL, BPMN, XPDL