Oct
19
2010

Our second wish to BPMN 2.1 in respect to process execution – human decision

BPMN example for a decision via gateway

BPMN example for a decision via gateway

In every process there are decision points. Conditions can be proved by the process engine by evaluating formulars defined on conditional sequence flows. So the corresponding parameters must be set within processing the task before (diagramm taken from discussion post of Keith Swenson).

We have learned that in the most cases the user should decide during forwarding the business case to the next task. So we are offering the user the decision as items in the context menu of the marked business case in his inbox. For getting these menu items the process analyst can model this as follows (diagram was created using Signavio):

Modeling human dicision with SAPERION/Siganvio

Modeling human dicision with SAPERION/Siganvio

This seems to be BPMN 2.0 conform, but this isn´t. Conform is not to use a gateway but the use of two conditional sequence flows. The problem is that the menu items “approve” and “reject” are defined in the BPMN attribute “Condition Expression”. But how should the process engine know whether to produce menu items or to only evulate that expression after the forwarding request of the user? Our solution was to take another SAPERION specific attribute “Manual” which has to be checked for offering the expression entry as menu items.

Keith Swenson has missed this human decision handling last year and has proposed  another solution in his post Representing Choice in a Process Diagram:

Rejected proposal for making human decisions visible in BPMN 2.0

Rejected proposal for making human decisions visible in BPMN 2.0

His idea was to offer a new empty attachable event. The label on the outgoing sequence flow could then be used for offering the menu item, in this case “hire” and “fire”. When I read this I was happy with it. But another BPMN expert, Bruce Silver, has stated in his post Keith’s Choice that attached events are no good solution. They show the unusual leaving of a task, which isn´t the case with this manual decision.

The proposal of Bruce was, that BPMN should offer another type of sequence flow with an own symbol on the beginning of its shape.

But what a pitty: nothing to see in the current beta version of 2.0. So we want to reactivate this proposal to become more BPMN conform in future!

See as well our first wish for BPMN 2.0 – organisational structure model

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Written by Dr. Martin Bartonitz in: english,general | Tags: , , , ,

9 Comments »

  • Good post. This is an important topic too long overlooked. I keep finding many example of people using out bound arrows of activities to represent “choice” of the user. This pattern is common in human process modeling, but strangely absent from the BPMN standard which is supposed to represent human processes.

    If you have not already, join the BPMN Users Group for discussion of these topics:

    http://groups.google.com/group/bpmn-users-group

    More related posts on my blog using the following search:

    http://kswenson.wordpress.com/tag/bpmn/

    I am reminded that my first request for this is more than two years old now, so don’t expect anything to happen quickly. However, which might be needed is a “profile for human process” — a specific subset with extensions useful for modeling processes that facilitate human work, instead of attempting to automate and replace people. That is a possible approach.

    Comment | 19 October 2010
  • Dr. Martin Bartonitz

    Thanks for your comment and your hint to join the discussion group, which I will follow derictly.
    Yes, my impression is, that too many person coming from the BPEL point of view may have influence to the spec. Otherwise some other more human-centric functions should be there, which I am looking forward to publishi our wishes.

    Comment | 19 October 2010
  • Hi Martin.

    We know the topic as well, the solution we did at one customer is to define the pattern that a gateway directly following a Human Task always is always treated as choice in the human task and therefor shown as buttons for example.

    But I agree, that a “real” solution would be even better! And I like an own icon on the outgoing path. The problem still is, that it is not easily seeablethat this is a XOR.

    Cheers
    Bernd

    Comment | 20 October 2010
  • Dr. Martin Bartonitz

    Hi Bernd,
    yes, in case of a not used gateway one can currently not see whether it is an XOR or not. But if there is another “manual” sequence flow it is an implicit XOR, because the user can only select one menu item and ready.
    Cheers, Martin

    Comment | 20 October 2010
  • Rüdiger Molle

    Hi Martin,
    my proposal is to introduce a different type of gateway called “Manual Exclusive Decision”, the symbol can be a gateway symbol marked with “M”. It could also be “H” to indicate a human decision, but taking into account another situation where the decision is negociated between several users I prefer “M”. The negociated decision might than be described by a gateway symbol marked with “N” and will be interpreted as “Manual Inclusive / Negociated Decision”. Used together with gateways the leaving control flows will indicate the possible alternatives or negociaters of the decision. Within the Signavio context “additional partipants” associated to the gateway can be used or comments added otherwise.
    Regards
    Rüdiger

    Comment | 22 October 2010
  • Dr. Martin Bartonitz

    Yes, this could be a solution. The negative side of this solution with gateways is that you have to use one and there is then one additional element. Less should be more. I would prefer a solution where such a behavior is defined in properties of the human activity or in the type of flow.

    Comment | 22 October 2010
  • Rüdiger Molle

    Hi.
    To me an additional element seems to be not avoidable in order to make the situation visible: integrating a human decision in the activity makes it unvisible in the BPD, when it comes with the type of flow, it will also be represented by an additional element or element type. In this case an exclusive or inclusive human decision must be modeled or the way it will be carried out must be left to the execution environment. With a gate the participants or lane representatives will simply be posted as usual.
    Regards
    Rüdiger

    Comment | 29 October 2010
  • I fully agree this is a weakness of BPMN.
    We propose an approach based on “user gateways”, you may want to read about it here:
    http://marcobrambi.blogspot.com/2011/01/user-gateways-in-bpmn.html
    Do you think this could be helpful?

    Comment | 11 January 2011
  • Dr. Martin Bartonitz

    Hi Marco,
    Yes, I think this is an alternative which can work, Especially in the case a non human task is predecessor. Otherwise the workflow client should handle it in a handysome manner in reducing clicks. In the case a human task is predecessor your solution needs one more object. May be that less is more?
    Martin

    Comment | 12 January 2011

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