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Transient Trigger - Message or signal intermediate Event needed?

Hi

In "Modeling Workflow Patterns" in the following link:

http://bizagi.com/docs/Workflow%20Patterns%20using%20BizAgi%20Process%20Modeler.pdf

for pattern WCP 23 - Transient Trigger(page 49 of handbook), a "Signal" is mentioned for triggering another part of the process but in the graphical example "Message Event" is used. Since the pattern tries to describe a transient situation, Signal event must be used in my opinion but the description in handbook and graphical example have conflicts with each other. Would you please update me which one is correct? Message or Signal Event Many thanks in advance

Lachin

Best Answer
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Dear Lachin,

Thank you for your feedback.

We clarify that Signal is not strictly needed (it could be Message as well, as stated in the implementation's text).

In the actual example, a Message Event is used because the 2 processes are modeled having messages that communicate them on a one-to-one basis.

As you may notice, the use of a Signal in this example would mean that it would trigger many other instances (a "broadcast").

We will however, perform an adjustment in the handbook, as per your observations, to clarify in the pattern description that both could be involved.

Best regards,

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0

Dear Lachin,

Thank you for your feedback.

We clarify that Signal is not strictly needed (it could be Message as well, as stated in the implementation's text).

In the actual example, a Message Event is used because the 2 processes are modeled having messages that communicate them on a one-to-one basis.

As you may notice, the use of a Signal in this example would mean that it would trigger many other instances (a "broadcast").

We will however, perform an adjustment in the handbook, as per your observations, to clarify in the pattern description that both could be involved.

Best regards,

photo
0

Hi Daisuke

Since in the description of the pattern WCP 23 is written that the trigger would be lost if not acted upon “immediately”, I think Signal Event better describe the situation.

For me the only difference between WCP 23 & WCP 24 is the difference in lifetime of Triggering Events. Email can be waiting to response (Persistent Trigger) but Signal disappears if there is no active process to wait (Transient).

Actually I think the example for WCP 23 is not sufficient to describe the situation of Transiency.

It is much better to describe WCP 24, in my opinion with the diagram 39.

I am putting an example here which I think it describes the situation of Transiency better.

When a car in a shopping mall parking is with lights on an announcement must be done to inform car owner to turn the lights off.

The participants are the store(s) and the shoppers. We don’t know whose car it is, so the announcement describes the car. You don’t know which of the shoppers the car belongs to. You must announce to every shopper. Second, you don’t even know if this is in fact a shopper that owns the car. The car could be owned by an employee, or it could be a shopper in another store. So the actual participant in this case is anyone that might potentially park a car in the store parking lot (potential car parkers).

As you can see in example, the signal event is also limited by the attributes “Black”, “BMW”, “Plate Number″. So if I don’t have a black car I immediately ignore the rest of the message. Or if I have a black car but it’s not a BMW I can ignore this message. The point is the responsibility of the potential signal receiver to identify himself and act accordingly. Nobody is going to make you go turn off your lights. From the perspective of the store, they have fulfilled their obligation by making the announcement.