Agents: Method or Rule - WF more robust vs. better performance

Question

Hi all,
we are in ECC 6.0 and building several workflows to cater for HR processes. These workflows will be implemented globally.
Earlier this year, this thread talked a bit about this and I am using some of the statements from it in this post:
Responsable agents: What's better? Role or expression (variable)
We are writing a function module to Find Manager. What I am trying to determine is the best way to use this function module. I can either create a method to call it, or I can create a rule (called 'role' up to 4.6) to call it or I can create a virtual attribute to call it.
This function module will be called a lot as most of the workflows will involve the employee's Manager.
If implemented as a method, an RFC is used and I will need 2 steps in the WF - but I will be able to 'trap' any errors returned by the function module, e.g. manager not found, and use the returned exceptions within the workflow. The method can be implemented in a generic WF_UTILITY class/BOR, it doesn't need to be linked to a particular class/BOR.
If implemented as a rule, it is 1 step instead of 2 - less logs, better performance. But if the rule fails, the workflow goes into error. I do not think there is a way to avoid the workflow going into error.
I might be able to create a virtual attribute for it, but one of the parameters for the function module is the workflow that is calling it & it will also mean that I would have to make sure that every workflow has an instance of the object that I implement the virtual attribute.
Is it worthy to 'trap' the errors and deal with it within the workflow? Or it is better to let the workflow go into error?
Please let me know your thoughts on this one.
Much thanks and regards,
Cristiana

Answer 1

I agree with Raja that you should choose the approach with rules. In your version you can also use tools to re-evaluate rules for active workflows to redetermine the agents, an option you lose if you implement it as a virtual attribute.
Let the rule fail (flag HRS1203-ENFORCE set, the checkbox at the bottom of the rule definition screen) if no agent is found. Don't harcode sending it to anyone if no agent is found, that just gives you less flexibility. Whether the workflow administrator receives a work item in the inbox or sees it in the administrator transactions shouldn't make much difference to an administrator.
If you want to avoid the workflow going into error (sending it to an administrator is not better than letting it go into error, it is just an error handling strategy) you must as in all programming have defined rules for handling the known problems. This could e.g. be a table which specifies who will receive the workflow (with as many parameters as you like for finding the most relevant person) if the proper agent can not be found. I have implemented solutions along those lines, but it always boils down to finding someone who will accept having responsibility for handling errors.