Information Technology Reference
In-Depth Information
The server failover and distribution mechanism
Whenever we have generic systems that might cover very diverse cases of our organiza-
tion, it becomes more and more important that we have a way to scale up such applications.
In order to do so for a BPM system, process persistence is the key. This is because it will
not only release precious memory resources when not needed, but also allow the creation
of different nodes in a High Availability grid managing said processes if they have more
idle time, all synchronized through the database.
However, this carries another issue that we should discuss: the possibility that two different
servers (or even two different threads in the same server) may try to access and change the
same process instance simultaneously. This can be solved in the same server with very
simple in-memory synchronization mechanisms. However, when you have different servers
competing for the same process instance, we need something more powerful, that is, trans-
action management.
Transaction management allows us to make sure that different servers will not work on the
same process instance at the exact same time, and persisted process instances will not be
persisted if a runtime error occurs (a possibility provided by the rollback capacity of trans-
actions).
Now that we understood the necessity of persistence and transactions in a BPM system, it's
time to analyze how these components are provided in jBPM6.
