| A single, local instantiation of a
FlowDefinition flow definition launched within an overall flow execution.
This object maintains all instance state including session status within
exactly one governing FlowExecution, as well as the current flow state. This
object also acts as the local "flow scope" data model. Data in
FlowSession.getScope() flow scope lives for the life of this object and is
cleaned up automatically when this object is destroyed. Destruction happens
when this session enters an end state.
A flow session will go through several status changes during its lifecycle.
Initially it will be
FlowSessionStatus.CREATED when a new execution
is started.
After passing through the
FlowSessionStatus.STARTING status, the flow
session is activated (about to be manipulated) and its status becomes
FlowSessionStatus.ACTIVE . In the case of a new execution session
activation happens immediately after creation to put the "root flow" at the
top of the stack and transition it to its start state.
When control returns to the client for user think time the status is updated
to
FlowSessionStatus.PAUSED . The flow is no longer actively
processing then, as it is stored off to a repository waiting on the user to
resume.
If a flow session is pushed down in the stack because a subflow is spawned,
its status becomes
FlowSessionStatus.SUSPENDED until the subflow
returns (ends) and is popped off the stack. The resuming flow session then
becomes active once again.
When a flow session is terminated because an EndState is reached its status
becomes
FlowSessionStatus.ENDED , which ends its life. When this
happens the session is popped off the stack and discarded, and any allocated
resources in "flow scope" are automatically cleaned up.
Note that a flow session is in no way linked to an HTTP session. It
just uses the familiar "session" naming convention to denote a stateful
object.
See Also: FlowDefinition
See Also: FlowExecution
See Also: FlowSessionStatus
author:
Keith Donald
author:
Erwin Vervaet |