SOA/BPM performance best practices (End user interaction considerations)

When designing the end user's interface and interaction with the BPM system, one mainly has to deal with getting a list of tasks to be worked at, claiming tasks, and completing tasks.

Querying to-do tasks
Experience has shown that when end users have large degrees of freedom in filtering and sorting the list of tasks they have access to, that they might develop a kind of cherry-picking behaviour. This might result in much more task queries being performed than actual work being completed. Cases of a 20 to 1 ratio have been observed. When the nature of the business requires the flexibility of arbitrary filtering and sorting, then there is not a lot that can be done, but if this freedom is not necessary, it is advisable to design the end user's interaction with the system in a way that doesn't offer filtering and sorting capabilities that aren't required.

Concurrent access to tasks
When two or more persons try to claim or check out the same task from their group's task list, only the first one will succeed. The other persons will get some kind of an access error, when trying to claim a task, that has been claimed by someone else before.
Such claim collisions are counterproductive, since they usually trigger additional queries. A possible remedy would be to design the client side code in a way that whenever a claim attempt reports a collision that the code randomly tries to claim one of the next tasks in the list and present that one to the end user.
The probability of claim collisions becomes larger with the number of concurrent users accessing a common group task list, the frequency of task list refreshes, and the inappropriateness of the mechanism to select a task from a common list. Claim collisions not only cause additional queries to be processed, they also can frustrate the end users.

Multiple task assignments
The previous sub-section suggests to keep the number of persons accessing a common task list “small”. If instead of putting it on a common task list, a single task is assigned to multiple people, similar collision effects can occur. Keeping the number of persons a single task is assigned to as small as possible is again a good strategy.