Calling Expression Rule inside Timer Event

Question

We have a requirement to build the scheduler process to run 3 days before every quarter. The Logic has been built in the expression rule . When I am trying to call the rule in the timer to get the specific day to run, the process is not running whereas when I implicitly paste the logic, it works. Is there any limitations that expression rule can't be evaluated inside the timer.

Mike Schmitt · Answer

I'm a little fuzzy on this, but I think you have to assume the value of the timer expression (whether based on an expression rule, or hardcoded) will be evaluated upon activation of the timer node (or upon publication of the process model for start process timers), and no changes to the value or output of the expression after that point will have any effect.

Chris · Answer

Yes, agree with both comments here. You will also note this if you set a start timer for a process model based on a constant, then you change the constant later, the process model start time will not change until you re-publish the process model, at which time the timer re-evaluates against the new constant value. 
 We use Stewart's solution typically - have a parent process start an instance every day, run to an XOR node where your rule is evaluated to determine if it is the correct day. If it is the 3rd day before the quarter, continue to the process. If it is not, simply exit to an end node. Have a short cleanup period on the processes and this should work fine for you.

Mike Schmitt · Answer

Much as I said in my earlier comment on htis post, I believe * any * expressionable content on the execution time / start time for the process is evaluated at publishing time and not again until re-publishing. When you use an expression rule as a container for some more advanced code like this, you should usually assume it will act exactly the same way as if you hardcoded that same code direclty into the expressionable box in the process model itself. If you're seeing any behavior that seems to defy this, then you need to post some clearer code snippets / screenshots, because the single screenshot you've posted in your earlier comment doesn't really show us anything.

Calling Expression Rule inside Timer Event

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