A Theory of Service Behavior tries to formalize – as the name sais – the behavior of a service. This is in contrast to the syntax of a service, that merely describes the datatypes, that need to be used – which is commodity. The behavior if a service describes the order of allowed operation calls / message exchanges with a service.
This is a similar field, that BPMN 2.0 Choreography models. However the BPMN 2.0 Choreography Model is an abstraction, while there are different detailed representations, for different purposes.
So the paper proposes, that for the purposes of service validation, (automatic) service construction, service composition and service replacement there is not yet a represenations, that allows for a closed theory – i.e. a structured solution in all cases. Actually it is an opening paper that will be later completed by describing “operating guidelines”, which are intended to fulfil this purpose.
My personal opinion is, that is it a good endeavor. Such work is needed to complete the foundation for modeling tools, that allow for more comfortable modeling consistency checks and functionality.
I especially see much benefits in consistency checking. I also have one or two patents in this area. Important in my view in consistency is a clear definition of the goal of the check and a good method to explain consistency errors to the tool user. Consistency checking is in most cases useful. One needs a little bit of patience, to make a service definition fit to another, because there is always this one unwanted execution that needs to be eliminated. But it is worth the effort, because it is better to eliminate these errors in modeling time than in runtime.
Service construction is in my personal opinion difficult. In my view there are always abiguities in such an endeavor. So I prefer “human” design plus consistency check.
Service composition promises some benefit – especially if there is a skeleton composed, which can be further edited by the human designer. Also here it is important to formulate clear goals of the service composition and to have a complete – i.e. without gaps – description of the underlying services. Especially if there is a Business Process Platform that offers services, that need to be composed, and that is model driven, this is very promising. There are also other projects working on this. I may come back to this some other time.
Service Replacement is certainly an interesting application. If a service is changed, then it is certainly worthwhile to know potentially which consuming services might be affected and which not. This may be the outcome of this part of the research.
So good work – keep it going!
If there is an architecture with a Business Process Platform, then there is the question, which role do the process instances play in such a system.
The business processes are reflected by business objects themselves, which are linked with each other. Events are correlated to the business objects. This makes sense, because the business objects are clearly identifiable, because they are related to a concrete business transaction. There are concrete customers related with it, suppliers, products, dates – the things that make them easy to identify and find.
In contrast, if there are process instances, which have only an anonymous ID, like a Globally Unique Identifier (GUID), then the relationship to a concrete business transaction is rather loosely. Therefore it is hard to manage them. Furthermore if there are business attributes inside of the process instance, typically they are in generic containers (not always) and therefore difficult to use in queries.
So which process instances are needed within a Business Process Platform beside the business objects themselves? Probably some for approval. Some for ad-hoc processes. Not much more comes to my mind.
Monitoring a business process itself is a different story. For this not process instances are needed, but chains of business objects that are actually process objects and some process instances – that I already mentioned.
Unstructured, Semi-Structured and Structured Processes makes a distinction between
- structured,
- unstructured and
- semi-structured
processes, that I like. It is interesting, that in the definition of process the emphasis on the post is less on the sequence of activities, but more on the business goal to reach. That was, what I proposed earlier. And it makes sense. In the end it is more important, what the result of a process is, than what has been done or should be done in which order to try to (!) achieve it. I said “try to” because sometimes just doing a thing can not guarantee that the desired result is achieved. That’s why I say that the result is more important than the doing of an activity or task itself.
Of course it is inevitable that when a business process is implemented in an business process platform, that it is structured. Otherwise it is impossible to implement the business functionality that transforms the business objects that are part of the business process from one state to another. That is said modulo that there may be some generic functionality like a process engine for workflow or generally for execution of modeled process parts of course.
BPMN supports some Ad-Hoc modeling cababilities. There are Ad-Hoc tasks where the sequence is not defined or where it is not defined if none, one or all of them are executed. However one would expect, that any task that can be executed is modeled – at least if it is not, it can not be system supported. Also it is a difference, if the Ad-Hoc cababilities are on the process type level, or on the instance level, meaning that a concrete process instance can be adapted to a new, unexpected flow, sequence or even new Ad-Hoc Tasks.
However the more the tasks become Ad-Hoc the more they become an empty shell. What do I mean by this?
Create an Ad-Hoc task “Calculate stock losses based on financial crisis”. Of course if this is done the first time, there is no busines logic implementation for this. Even if there is a SOA service offering the solution, there needs to be some implementation of calling the service, which means gathering and providing the needed parameters and using the result in other processes.
So – as soon as a process is implemented in a business process platform it has at least some constraints.
Which is ok – because it has been formalized, because it’s execution is more repetitive.
On the other hand especially in times of crisis the importance of Ad-Hoc processes grows to account for the need to compensate unforeseen difficulties in the daily “business as usual”.
The important thing is, that the structured, the unstructured and the semi-structured processes can be integrated as seamless as possible. This is only possible, if there is a common notion of result of a process or of an activity in the process. Furthermore it is an interesting question – especially in semi-structured processes – how much constraints are desribed.
- None Constraints: Unstructured.
- Some Constraints: Semi-Structured.
- All Constraints: Structured.
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