Information Technology Reference
In-Depth Information
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Start events
: These events are drawn with a single, thin border line. They repres-
ent an external interaction that causes the beginning of a business process in-
stance.
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Intermediate events
: These events are drawn with double, thin border line. They
are in charge of catching external events or throwing events, even outside the pro-
cess instance scope. They can influence the flow of the process, but they cannot
start it nor end it.
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End events
: These events represent the end of a process instance or the end of an
execution path inside a process instance. It is always sent and never received from
outside the process instance scope.
For each main type of event (start event, intermediate event, and end event), there are
many subtypes defined by the specification. For example, the last three events in the pre-
vious diagram are specific subtypes. The terminate end event marks that all the active exe-
cution paths in the process instance must finish, as long as one path reaches said node.
The intermediate timer event will wait for a given amount of time before continuing with
the execution flow. Finally, the start signal event will start a new process instance when an
external signal of a specific kind is sent to the runtime environment. There are many
more; but for the first examples we'll see, these will suffice. Support for a wide variety of
all three main types of events is provided by jBPM6.
Activities
Activities define a piece of work that is being done inside the process scope. They could
be atomic or nonatomic activities, depending on whether they can be further divided into
more activities or not. For such purposes, the standard defines three different types of
activities: tasks, subprocesses, and call activities. These are represented as boxes in the
following diagram:
As seen in the preceding diagram, a rounded rectangle defines a task, which can have dif-
ferent subtypes. An icon on the top-left corner can define different types of atomic activit-
ies, such as User tasks (a human should provide a specific input in these kind of tasks), a
Script task (when a particular piece of script needs to be executed), a generic task (it will
have no icon and is thought to be defined in runtime), or many more.
