Frank Michael Kraft's Blog

So – it is very useful to have this tool for the top-down design of process interaction now. Inversely it can be used for the validation of an already existing bottom-up modeling. In reality it will be a mixture between the two. It is of central importance to have the enforceability in mind, that is to define a process, that is actually executeable by the participants. For this the model levels serve as basis for validation.

If we go down to the technical modeling, it is now possible to model Conversations, which are groups of Message Flows, Correlations, which are assignments between a message and a process instance, Service Bindings, Data Flow, … Compared to BPMN 1.2 the DataFlow is more than an artifact now (i.e. more than just a pictogram). It has a datastructure and the Activities have DataInput and DataOutput. Also the DataObject can be used as Parameterspecification for reusable Subprocesses. The Events have been enhanced. There are complex Events, Events , that can interrupt an activity or not, it is possible to define Event-Subprocesses that run aside from the Sequence Flow.

Here some critical comments from my side may be allowed. I think the workflow type of modeling is too strong in this. First there are strong sequence flow relationships established, only to be loosened later by many Events. I think it would be better for the future to define the relationships more loosely from the beginning. For example they could be modeled as preconditions depending on the status. That is something for the future.

Personally I found the discussion around the relationship between public and private processes very fascinating. One time it seemed like we had so many problems with it, that we could not do it. And additionally to this there was the climax of the debate with the concurrent submission. We were blamed, that our model was too strict. A very good discussion! But we found a very simple and elegant solution to these problems. The sequence flow is now not so strict than it was before. It has been loosened, and the difficulties disappeared.

Furthermore one important area is to have in mind the asynchronity of messages. That can produce race conditions between messages. However this in my opinion is not mainly a technical problem, but is due to the asynchronous nature of business processes, that I hope to discuss in the Blog as well in the future. Most problems on the message technology side can be avoided on the business process design level – and that is good news.

There are more changes from 1.2 to 2.0, but in my view these were the most important.BPMN has become quite powerful. Sometimes it is not so clear as to how to solve a certain modeling problem. However the success will depend on elaborating best practices and good guidance.

My wishlist for BPMN in the future? Modeling of Interactions with and of Business Objects. Find simpler ways to model special cases. Model a Process specific  Status.

But now is the time that BPMN 2.0 has to be used and proven in practice. After that we can establish our common opinion about the wishlist for the future. It is a language. And the vocabluary is only the beginning of the process to learn to speak that language. Therefore a good coaching process is what I can recommend.

Elaborating more on what I said before about loosely coupled processes, I want to emphasize today, that the cut of the processes is of major importance – i.e. which parts are loosely coupled and which parts are tightly coupled. Furthermore if process parts are loosely coupled, it is of big importance which process parts are public and which are private. Public process parts constitute a contract, that the other participant can rely on (when to request, when to confirm), while private processes are only needed within the operations of one participant’s organization – for example an approval or a special form of approval that is irrelevant to the other partner. This has these benefits:

• Flexibility: It is possible for one participant to adapt the private process to changes as business requires it without the need to negotiate with the other partner, as long as the change still complies to the public process.
• Stability: The participant can rely on the behavior of the opposite participant, even when the opposite participant makes changes that comply to the public process.
• Visibility: In Process Monitoring internals are not visibible because they should not. It is a decision of discretion which parts of the process should be visible to other partners. However I believe that BPMN 2.0 might be amended for this purpose, because for this it might be necessary that also non-communication activities can be part of a public process.
• Decoupling: The number of private processes that comply to a public process needs not to be multiplied with the number of choreographies, that comply to a public process. Say you have 3 choreographies that you want to combine with 3 private processes. Then without decoupling you have 3*3=9 process models. With decoupling you have 3 + 1 + 3 = 7 process models.

It is important to understand, that the Choreography is an abstract process while the private process is a concrete process – i.e. can be executed by a process engine and has process instances. So the Choreography Model will never be executed by a process engine. It is the summary view of the participants. It never proceeds on it’s own. It proceeds, if one of the participants proceed (as far as the public process is concerned).

If you ever tried to build a central process with process instances that decide about the message flow, you might have tasted how difficult that is. For simple processes this might still be possible. However you always find these difficulties:

• Either the central process does not have enought information to decide – and that are business decisions in the end – or
• The central process needs to know nearly everything.
• As soon as information reaches the central process by means of messages, it is already outdated (because the sender might have evolved in the mean time).
• Also in many decisions it is necessary to involve humans, not just rules.
• If humans are involved, they might not only to decide left-right, but regroup – solve differently (e.g. create return instead of lowering delivery quantity).

This all leads to the conlusion, that I have made for myself: If there is a middle tier, it needs to be a full fledged business application in the end. With business objects, UIs and the like.

Then we have 3 partipants instead of 2 – which is fine. Then we have 2 Choreographies between them, which are still abstract.

Some words about the BPMN 2.0 process as I personally percieved it.

I found the collaboration between the companies very productive. Often some have a hidden agenda or have prejudices. In this case I can testify, that I personally did not perceive such a thing.

Of yourse every company has it’s worldview. I found IBM had the strength in workflow technology and metamodeling. I found, that Oracle had an especially deep knowledge in message exchange. And SAP had extensibe experience in business processes and their modeling.

There were strong contrary positions, due to the fact, that there were two different consortiums that prepared a submission.

• Adaptive, Axway Software, Hewlett-Packard, Lombardi Software, MEGA International, Troux, Unisys.
• IBM, Oracle, SAP AG, and Unisys.

There was a collaboration of project management level and the assessment of a common submission. On the concept level there was the discussion of BPDM (Business Process Definition Metamodel) should be the unterlying meta model or not, a 2007 OMG standard for a general exchange format for processes.For IBM, Oracle, SAP a native BPMN metamodel with possible mapping to BPDM was the course we chose.

But there was a very productive part in this controversy. Because members of the other submission team joined also our discussion, our discussion was much enriched. Especially the contributions of the NIST (National Institute of Standards and Technology of the US) revealed many special cases that can happen during message exchange, that were not previously in the discussion. I found that especially inspiring, because I had encountered many of these special cases previously in my architecture projects. That was about the same time that I joined the discussion in more detail. However within the BPDM approach I found some pre-determinations that I definitely could not follow. For example I could not agree, that temporal relations (i.e. that message has to be earlier/later than that messate) should be the main way to describe relations, because in my opinion mere temporal relations do not sufficiently describe cause/effect relationship or constraints between exchanged messages. However there was a significant openness in the discussion that allowed us to find compromises that could achieve very good advances to adress use cases. I personally had significant objections to the choreography modeling. However they could also be resolved – not so elegantly as I had wished – but resolved.

However this was a very interesting discussion, that was not fully completed within the scope of BPMN 2.0 and that I hope I can follow up in the near future.

In the next blog post I will go into details of the my view on BPMN 2.0 and the new modeling possibilities that it offers.