Information Technology Reference
In-Depth Information
When the rounded rectangle has a particular sign on the bottom, the activity is considered
as a subprocess, which means that it can be decomposed into different activities. Depend-
ing on the sign, it can mean that the round rectangle will contain many subactivities that
are just not relevant to the current process definition's scope. This can be executed once
(when it is a plus sign) or many times (when three parallel lines are on the bottom). Usu-
ally, these subactivities are embedded inside the subprocess activity box.
Finally, if we want to invoke a process definition defined outside the scope of the current
process, we use call activities. This encourages reutilization and transfers the control of
the execution to the activity being called. Call activities are defined by a thicker border
line, like the third rectangle from left in the previous diagram.
All of these types of activities, tasks, subprocesses, and call activities are supported by the
jBPM6 process designer at runtime.
Gateways
Gateways control the divergence and convergence of sequence flows in a process. They
are represented by a rhombus, and the drawing inside the rhombus determines the differ-
ent types. The following diagram shows examples of different BPMN gateways:
BPMN2 gateways have one outgoing connection and many incoming connections (when a
gateway is diverging), or many outgoing connections and one incoming connection (when
a gateway is diverging). The most commonly used gateways are as follows:
•
Exclusive (or XOR-based) gateway
: This is marked with an
X
sign and it allows
only one outgoing execution path to be executed, depending on conditions
defined in the outgoing flows. When converging, it carries on whichever path
reached it, because it expects one flow to be executing only.
•
Parallel (or AND-based) gateway
: This is marked with a plus sign and allows us
to define concurrent paths. When diverging, it creates a new execution path for
each outgoing connection; when converging, it waits for all connections to finish
and carry on with one execution path.
