BEAParticipate: Advanced Process Modelling

Last session of the morning was Mateo Almenta Recca of BEA and Kunal Shah of Citigroup talking about advanced process modelling — specifically process exceptions — in ALBPM. Exceptions can be either system exceptions, such as a service being unavailable, or business (user-defined) exceptions, such as an account being closed. System exceptions are typically handled through automated retries and/or transaction rollbacks, whereas business exceptions are modelled into the process by the process designer.

Exception handlers can be built into the process at either the individual activity, group (similar to a BPMN transaction) or process level. Exception handlers at an activity appear just as an alternative path out of that activity, although an exception is typically invoked by a timeout or other non-decision activity instead of an explicit decision at that point. Exception handlers at the group level are shown connected to the group wrapper boundary, as in BPMN transaction exceptions, and process exception handlers are visualized as disconnected from the process but on the same model.

All exception handlers can take one of three basic actions: abort the process and go to the end of the process, go back and retry the step that threw the exception, or skip the step that threw the exception and move on to the next step in the process. The back and skip functionality is always at the activity level: an exception at the group level that causes a “back” instruction from the exception handler would return to the specific activity to be retried, not the entire group; “skip” would skip the activity but continue on to any later activities in the same group. This was counter-intuitive for me and I asked specifically about that: I would have expected that a group would be treated more like a BPMN transaction wrapper, such that a retry or skip would apply to the entire group, not the specific activity. Exception handlers can be automatic or manual steps: an automatic exception handler might perform some related transaction rollback in another system before aborting a process, for example, whereas a manual exception handler might allow for data repair before retrying the failed step.

They then talked about compensation flows, which seems to match the BPMN meaning of a compensation, in that it reverses a completed activity or group of activities. This isn’t so easy as just rolling back any changed data values in the process instance, since there may have been external systems updated that now need to be rolled back to an earlier state, or non-transactional activities such as sending an email. Compensation flows are used when you can’t use automatic rollback because an activity executed successfully, but can also be called by exception handlers. Visually, these appear very similar on the process model to exception handlers, in that they can be attached at the activity, group or process level. Since groups can be nested in a process model, the compensation flow for a group will invoke the compensation flows for any groups nested within it as it rolls back the entire flow of the group.

They finished up with a short Citigroup case study on how they handle trade exceptions in their back-office processes. Although most financial trades are handled straight through with no manual intervention, they handle 2000 trade exceptions each day. From designing a number of similar transactional BPM implementations, I know that there’s huge financial risk if you don’t handle your exceptions in a timely manner: market fluctuations that occur after the trade is accepted and priced but before it’s completed are purely the risk of the financial institution, not the customer, so it’s key to get the exceptions resolved as quickly as possible. Citigroup has implemented this as process-level exception handlers that log the exceptions and pass them on for manual review. In most cases, the exception handling process is just a matter of some manual data repair and the trade is resubmitted to the automated process, although some trades are cancelled from within the exception handler.

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