BPEL Anyone?

Question

I saw an excellent presentation on Seam, and aside from its integration with JSF and EJB 3.0, I was particularly interested in how they worked in JBoss's version of BPEL, jBPM. I'm not 100% sold on BPEL, but it definitely seems like a great way to reduce coupling and complexity in larger enterprise systems.
Anyone been using BPEL? Ready for prime time yet? Or was it a horrendous mistake that is now being undone? :^)
- Saish

Answer 1

I've looked at it as a replacement for Tibco's BusinessWorks application which is one of the biggest dogs I have ever worked with. Before anyone asks, I don't have time to describe all the issues with that tool. Just know that it is extremely painful.
The WYSIWIG editor for the workflow or the tool itself? (Or both, I guess)
Having said that, the idea behind it is pretty good for a workflow type archtecture. BPEL seems to be a standardization of that kind of environment. The one thing that I would caution you on is trying to do too much in that kind of environment. It's not a replacement for a text based language like Java. It's a complimentary tool. If it is like BW (and I'm pretty sure it is) it excels at modelling high level transactions and business logic. We are talking coarse-grained steps here. Big time. Use good OO design to build the lower-level system logic (using Java most likely) and call it from BPEL.
That's my initial impression as well. I remember reading in "Pragmatic Programmer" the idea of a 'blackboard' for really complex workflows and business transactions. To me, BEPL seemed a good way to implement a 'blackboard'.
At least in the original Seam presentation, Gavin King went over the various additional 'scopes' that Seam provides. One is 'between' request and session, called 'conversational'. Pretty slick in that it allows MDI usage of a web app without contentions in HttpSession. More pertinent to this discussion, though, was 'business process' scope, which was 'beyond' application scope. Bascially, he hooked Seam into jBPL to store incomplete workflows until they were ready to go to the database for storage.
Anyway, there are lots of free impementations. Give it a swing and let me know if I make any ddamn sense.
Definitely makes sense. And thanks for the as always salient reply!
One thing that BW desperately needs is a good scripting-language (Python, perhaps) based activity. Some things don't quite warrant a whole Java object model and don't quite work with boxed and arrows either. You might want to look for a way to do that before you end up with a big mess, if you start using it.
I'm thinking of handling large-scale events in the system (say when an application is completed and can be processed internally, then when ready for customer review and then final handling.) So, really, I'm thinking of using BPEL to represent large components in the system as state machines, governing the allowable transitions from one, large component state (or system state) to another for a given workflow. (Sorry to be vague, but I'm trying to keep things at a high level now).
I also think there's room for a rules engine somewhere in the mix. The workflow itself is fairly standardized, though there are multiple paths to a given component event. It's in each component that regulations vary from state to state or county to county. So it seemed to me that one could get a lot of bang for the buck via:
Using EJB 3.0 for transaction management and JPA for O/R mapping. Much of the system already uses Hibernate.
Use BPEL for high-level state transitions in workflow that are too complex to model in either EJB or POJO's, since most of the transitions are 'orthogonal' to the object model itself, similar to aspects.
Use a Rules Engine for the complex variety of validations that occur in the object model itself. Again, so that the object model is cleaner and concerned with fewer duties.Finally, it seems to me that one additional advantage, though I am dubious it can be achieved in reality, is that theoretically a business analyst can develop BPEL graphs and potentially write additional rules engine ... err ... rules if the grammar is English-enough.
Ah, I'm rambling. I'm just honestly excited about BPEL and not totally sure what the best use of it might be. :^)
- Saish