INTERVIEW QUESTION:

Describe the BPMN Event-Based Parallel Gateway and how it is used in process modeling?


The more common BPMN gateways that you might be familiar with are usually data-based gateways. These include the inclusive and exclusive gateways. Here is the list of all the BPMN Gateways.


When a data-based gateway is used, the value of a data element is evaluated by a condition statement to determine which path the process should proceed along. 

BPMN also provides event-based gateways. Event-based gateways do not evaluate data.  Instead, event-based gateways wait for an event which is then used to determine which path the process should proceed along.  An event-based gateway is required anytime a decision is made by another participant based on data that is not visible to our process.

Sometimes, the start of a process is dependent upon several events having occurred.  In this instance a Event-Based Parallel Gateway is used.  
 
BPMN Event-Based Parallel Gateway
 
If you examine the icon used for the BPMN Event-Based Parallel Gateway you will see that it inherits elements from several other BPMN icons.  First, there is the diamond which clearly shows it’s a gateway.  Per the BPMN specification, this gateway is only used to branch the process and is not used for merging or synchronization.  Within the diamond shape, there is a single circle representing a start event.  Finally, there is a plus shape which represent that all of the following events should occur in parallel.  So the Event-Based Parallel Gateway is a gateway that waits to receive multiple start events and allows them all to proceed in parallel.

It is important to note that while the Event-Based Parallel Gateway will allow multiple events to pass through and start the corresponding portion of the process, it does not wait for all of the events to arrive. That is, it does not wait and synchronize the events before the start of each process path is permitted.

posted @ Saturday, July 6, 2013 4:30 PM by Chris Adams