I was recently asked if I like this idea: Handle everything, that is coded in an ERP systems today as Process Patterns and instead design it as process models, that can be adapted to the requirements of the customer. The context of the discussion was if the combination of ERP/BPM/SOA would not have tremendous potential.

I aswered, that I have experience with that and that I agree that there is a tremendous potential with that. That really was an interesting discussion, because I did not hear such analysis before in the discussions in the public marketplace. I think this is the right direction to think.

I had already governed the design of the process of about 200 or more business objects, creating about 2.000 models including roughly about 5.000 web service operations. I didn’t use BPMN for that, because it was not flexible enough for this purpose, neither any of the existing languages. I used an own Domain Specific Language (DSL) for Modeling the behavior of those Business Objects.

My summary of that exercise is, that I agree to the original question. Only by modeling the process of Business Objects which are part of the ERP system, the ERP system’s web services will as a result have the right granularity. What is the right granularity for web services? Reusability. If web services are reusable, then they pay off most. In order for them to be reusable, they need to fulfil certain conditions. A web service operation should only do one thing at a time., i.e. not trigger an endless chain of activities in the system. It should have clearly defined preconditions. The effects and results of the web service operations must be clearly defined in terms, that can also be preconditions to other web service operations. That are the most important criteria in my view.

A system must be designed for this philosophy from the beginning. I strongly believe that adding web services to an existing system falls short of this goal. Even if it has some value, it would not use the full potential.

In general what I miss in the public standards is a language to describe the behavior of web services. Yes, BPMN 2.0 goes into that direction. But BPMN 2.0 still has to prove that it can fulfil the promise in practice. I think to a degree it can. It will turn out later, if it is possible to simplify the language or if it becomes an inspiration for other approaches (e.g. constraint based instead of workflow based).  And using BPMN 2.0 in itself does not guarantee the success. Additional guidance is necessary, certain quality criteria that each model must fulfil.

However, if the behavior of web service operations of an ERP system is defined, and if the granularity of the web service operations are so, that they are reusable, then the potential is very big. Because it means, that it is possible to attach own processes to that ERP service and even to interweave own processes in-between ERP processes. For example to add an approval before the release of an order under certain conditions, to add an own method of calculating benefits for the payroll and the like.

However as a limitation to the original question I would say, that not all of the processes modeled could be customized or changed arbitrarily. There are certain core processes, that the ERP system offers, that can not be changed without the danger of losing the consistency of the process. Therefore it is clearly necessary to describe which part of the process needs to remain stable and which parts of the process can change or are open for additions and interweaving. This of course must be part of the model.

Why I am looking at these MDA papers?

It is inevitable in big organizations, that there are central processes that are supported by every part of the organization. But at the same time it is desirable, to support individual processes, that respect local specialties. In this case the local units must be given the possibility to plug into the global processes. This can only be done, if the behavior of the local and the central processes is known – and by this the interaction – the choreography between them – can be defined and described. Therefore it is important to have behavior modeling languages for processes of units and of the choreography. Furthermore sometimes it is necessary to allow a local unit to describe their own processes or aspects of their own processes in their own language – a DSL – and plug them into the central processes.

If this is achieved it is a controlled powerful local flexibility with the integration into centrally controlled processes.

All of these articles and also BPMN 2.0 can help to strife towards this goal.

(Soden & Eichler, 2009) discusses the need of extending the Eclipse Modeling Project under which EMF (based on MOF) is used to define Domain Specific Languages (DSL) and GMF to define Graphical Model Editors and Xtext to define Human Understandable Textual Notations (HUTN) for a defined DSL with a Model Execution Framework (MXF) that allows for the declarative specification of a model execution and simulation.

The idea is to extend an abstract syntax, that defines a Domain Specific Language (DSL) – for example a finite state machine language – with a model that describes runtime instances of the model (including state, counter, … ) plus a declarative (in this case even graphical) model for the behavior of the model simulation.

What I like in the idea is the thrive to make the DSL architect more productive in his work by relieving his duty to implement a model interpreter or model to code translator, if he invents a new DSL. By this, he can write a new DSL (like for example BPMN 2.0) and would be able to simulate the behavior of the execution semantics without implementation work – just by declarative modeling. That is the promise of the approach.

One could discuss, if the chosen Language MAction is the best way to describe model execution semantics, but at least it has to be taken serious. For me this is an interesting DSL prototyping environment. If one looks at model execution at runtime, I do not think that the Eclipse Environment is the right architecture for this. But it is a start – as I said – for DSL Prototyping. Other points that should be discussed in the future in my opinion are:

• Runtime Optimization for the Model by adding shortcuts in the Runtime Model
• Modeling of big examples (like BPMN 2.0) with the new language
• Evaluation of different ways of describing the Model Execution Semantics

References

Soden, M., & Eichler, H. (2009). Towards a Model Execution Framework for Eclipse. First European Workshop on Behaviour Modelling in Model Driven Architecture (BM-MDA) (S. 57-71). Amsterdam, The Netherlands: Centre for Telematics and Information Technology Workshop Proceedings.