Frank's Blog

Enhanced eEPCs 

Today was the first time in my life that I wished for eEPC (enhanced event-driven process chains) stencils for OmniGraffle. Hence, I created a simple set that you can download here. The beautiful things that you can do with them are depicted below:

I introduced two visual extensions to the eEPC notation in the example. First, I'm depicting often executed functions larger, whereas seldom used functions are shown smaller. The same holds for events, systems, and roles. Via these simple layout changes, an immediate feedback of the important parts of an eEPC is given. This is quite important, since EPCs usually fill walls. As a second extension, I also depicted the often traversed edges in the diagram in bold. This also adds to an immediate visual feedback for the viewer. In my example, I simply assumed the important parts. If you have log data or annotations available, you could even simply automatically enhance your diagram.
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BPEL in Practice 

Today I found a very nice article about a practical application of BPEL that I cannot hide from you:

"Process Integration of Mobile Farm Machines Using Automatically Generated BPEL Processes.

Increasing IT requirements in agriculture and farming lead to situations where mobile farm machines need to be integrated in the business processes of a farm. Since these processes and the communication partners change with the farm the farm machine works for an adapted process description must be created and used. Due to the strong variability and heterogenity of the partners Web Services and especially BPEL constitute an adequate infrastructure for the generation of such adapted business processes. Starting point for this approach is a BPEL model which serves a a template for automatic creation of an adapted concrete BPEL process."

(cited from Wirtschaftsinformatik 49 (2007) 4, S. 289-294)

The complete text is in German, but it is nevertheless worth reading it. One last citation: What do you think is a farmer doing after he gets out of his bed? Answer: The farmer first configures his IT environment using a software solution. Well done!
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Good Enough 

Sometimes, I get asked why---and how---I wrote a doctoral thesis. There are some simple answers for the former question: Why?

1. Stay a student.
2. Get paid to be a student.
3. If you're out of arguments, you always have the doctoral joker ;-)

The second question seems to be more complicated, but indeed is also very simple: Do your job good enough. While people often search for something to become perfect, this seldom appears to be the same to other people. Just like the 80:20 rule, focus on the important things. Here is a simple graph to depict the idea:

The horizontal axis shows the time that flies by. The vertical axis shows the amount of additional knowledge you earn each time unit. In the beginning, you quickly graps knowledge. Over time, your reach the meridian. Then, you cool down. While you're still working on the topic, something absolutely new and directly related to your work is hard to find anymore. Finally, prepare finishing your thesis. The important point is to submit your thesis just in time. While you would still be able to find additional knowledge, it's not mattering for your thesis anymore. So, that's at least how I did it. And believe me, you can apply the good enough rule to almost everything!
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Compatibility and Conformance 

Welcome back to the research session. This time I've been explaining the difference between compatibility and conformance and raise the issues that need urgent research. Both terms are related to the area of service-oriented architectures:

Compatibility is the property of two or more services working seamlessly together. Usually, one service is treated as the requester, meaning it is the starting point for investigation. Seamlessly means without any deadlocks. Hence, compatibility extends traditional investigations of soundness for process-internal structures to a set of services. I always rely on interaction soundness, since it's a simple - but yet powerful - kind of compatibility notion. In a sentence, interaction soundness proves a business process to be compatible with a set of predefined services that can be dynamically bound to the requesting process.

Conformance is the property of a service implementation to share certain invariants with its specification. As can already be concluded, a useful definition of conformance is quite complicated. Traditionally, we can argue that a service implementation and specification are conform if both have the same observable behavior, i.e. they are bisimulation equivalent. While bisimulation equivalence is a valid property, it is too strong regarding practical application. Consider for instance:

where an explicit choice has already been made at design-time. While this might be a wanted refinement, specification and implementation are not conformant regarding bisimulation equivalence (Since the implementation cannot receive an expertise).

Another common conformance notion is simulation. If the specification can simulate anything the implementation can do, both should be conformant. In fact, this solves the problem illustrated with bisimulation. It raises, however, compatibility issues. Consider for instance the following figure

where two specification are compatible (i.e. they always interact deadlock free) but both implementations (that conform to the specifications according to simulation) are not compatible anymore! Indeed, it would be enaugh for both specification to only have their first activity and still be similar to their specifications!

The examples illustrated some of the problems that occur using bisimulation and simulation as conformance notions. We're currently working hard to find a suitable solution.
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I'm going to be an author 

While I didn't updated this blog for almost half a year, now the time has come to tell you something new. First of all, I finished writing my thesis and handed it in for review. (That's of course my excuse ;-) But having finished a scientific work about BPM is not absolutely satisfying me. Since I always need more deadlines to work for, I now transfer my findings into a textbook. The thing will be called nothing less than "Frank Puhlmann's Business Process Management: Design, Specification, and Analysis". As already my name as part of the title suggests - in combination with the subtitle - I'm going to present my very own approach to BPM in this book. The book will be split into three major parts, where in the first part a graphical notation for designing business processes will be introduced. This notation closely resembles a subset of the BPMN - restricted for usability. The second part will introduce the formal specification of business processes. I will present a straightforward semantics for the graphical notation using the pi-calculus (is there still anything else out there?). Using the formal specification, the third part discusses the analysis of business processes regarding structural criteria. Since a well designed business process is of course free of structural error, the last chapter also closes the link with the first one, where the question of "good design" is discussed. As an appetizer, I can already show you the cover design. By the way, I took the picture in Chicago, IL, where I attended the fourth international conference on service oriented computing last December.

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