Posted by: Adam Deane | 21/03/2011

The case of the missing OR

BPM Sherlock HolmesHorrendous ! Absolutely horrible! What a dreadful way to die, said Watson in shock.
He slowly walked over to the body, twisted and tangled up in a net of its own making.
Sadly, it looks to me like a clear case of suicide, remarked Watson in despair.

Wrong! pronounced Homes in a deep loud voice.
Wrong Watson! Look again! Look at the evidence!
This is no suicide. This is murder! And of the worst kind!

Are you sure Holmes? asked a puzzled Watson. It looks to me like suicide.
The workflow instance ran its course, got stuck at one of the business rules, and caused a bottleneck. It couldn’t rollback, it couldn’t go forward. Stuck.
The only thing the process could do was kill itself, and start a new one
How do you deduct that this a murder?

Look at the workflow body closely replied Holmes.
You will see the sign of the killer.

I am looking, responded Watson in frustration. I am looking, but I cannot see any signs. Everything seems to be in order. The workflow steps are neat and tidy, connected with business rules and flow activities. Looks very professional. Proper BPMN. Seems that the person modelling the process did a good job. I must admit that I don’t understand most of it, but it seems well designed.

Too well designed! retorted Holmes in anger. Swimlanes, events, activities and gateways – all put in to hide the killers real intention!
We are not taking about a natural death here. This poor workflow was modelled to death!

But who would do such a thing? cried Watson in anguish

We are looking at the work of our most dangerous adversaries, one so evil, that it makes Professor James Moriarty look like a schoolboy
We are speaking here of the professional modeller

Unlike most enterprise architects, business analysts and workflow developers that create workflows that embed exception handling in the workflow to pick up on human errors and deal with them – The professional modeller builds a perfect workflow, one that covers all bases.
All, that is until the workflow changes and causes a hole in the logic. And as business will always change – so will the business process.

Trying to build a perfect workflow is impossible and unrequired. Every workflow needs exception handling to deal with human nature. The professional modeller does not believe in human nature, thus he becomes our most dangerous adversary.

But how do you spot these professional modellers?

Elementary, my dear Watson. Look at the workflow, said Holmes.
Can you see the point where the process got stuck. That is called a XOR Gateway.
It’s only used by professional modellers
XOR, represents a decision to take exactly one path in the flow. More than one path cannot be taken – they are mutually exclusive, hence the name. This is the behaviour generally assigned to the professional modellers.

Most human beings would use an OR gateway. Its more intuitive. It’s easier to understand. It the human way of thought flow.
OR specifies that one or more of the available paths will be taken. They could all be taken, or only one of them. Simple. Logical.

Every profession adds their own quirks and acronyms to make them feel special.
Programmers use the term “jQuery”, Database professionals like using “left outer join”, the ECM crew will use “digital signitures” – all unrequired features that give them a nice buzz.
In our industry it’s XOR. Using it once shows wisdom, using it twice shows a user fetish, but beware of those who use it everywhere they can.

What do can do now! panicked Watson breathless and pale.
What can we do to stop it?

Nothing, said Holmes. we must wait till he strikes again, or learns from its own experience.
Meanwhile lets go to the pub….


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