org.springframework.webflow.execution
Interface FlowExecutionListener

All Known Implementing Classes:

FlowExecutionListenerAdapter

public interface FlowExecutionListener

Interface to be implemented by objects that wish to listen and respond to the lifecycle of flow executions.

An 'observer' that is very aspect like, allowing you to insert 'cross cutting' behavior at well-defined points within one or more well-defined flow execution lifecycles.

For example, one custom listener may apply security checks at the flow execution level, preventing a flow from starting or a state from entering if the curent user does not have the necessary permissions. Another listener may track flow execution navigation history to support bread crumbs. Another may perform auditing, or setup and tear down connections to a transactional resource.

Note that flow execution listeners are registered with a flow execution when that execution is created by a factory or restored by a FlowExecutionRepository. Typically a listener will not be registered with a flow execution at runtime, when the flow execution is already active.

Author:

Keith Donald, Erwin Vervaet

See Also:

FlowDefinition, StateDefinition, FlowExecution, RequestContext, Event, ViewSelection

Method Summary

void	eventSignaled(RequestContext context, Event event) Called when an event is signaled in the current state, but prior to any state transition.
void	exceptionThrown(RequestContext context, FlowExecutionException exception) Called when an exception is thrown during a flow execution, before the exception is handled by any registered handler.
void	paused(RequestContext context, ViewSelection selectedView) Called when a flow execution is paused, for instance when it is waiting for user input (after event processing).
void	requestProcessed(RequestContext context) Called when a client request has completed processing.
void	requestSubmitted(RequestContext context) Called when any client request is submitted to manipulate this flow execution.
void	resumed(RequestContext context) Called after a flow execution is successfully reactivated after pause (but before event processing).
void	sessionEnded(RequestContext context, FlowSession session, AttributeMap output) Called when a flow execution session ends.
void	sessionEnding(RequestContext context, FlowSession session, MutableAttributeMap output) Called when the active flow execution session has been asked to end but before it has ended.
void	sessionStarted(RequestContext context, FlowSession session) Called when a new flow session has started.
void	sessionStarting(RequestContext context, FlowDefinition definition, MutableAttributeMap input) Called immediately after a start event is signaled, indicating a new session of the flow is starting but has not yet entered its start state.
void	stateEntered(RequestContext context, StateDefinition previousState, StateDefinition state) Called when a state transitions, after the transition occured.
void	stateEntering(RequestContext context, StateDefinition state) Called when a state transitions, after the transition is matched but before the transition occurs.

Method Detail

requestSubmitted

void requestSubmitted(RequestContext context)

Called when any client request is submitted to manipulate this flow execution. This call happens before request processing.

Parameters:

context - the source of the event

requestProcessed

void requestProcessed(RequestContext context)

Called when a client request has completed processing.

Parameters:

context - the source of the event

sessionStarting

void sessionStarting(RequestContext context,
                     FlowDefinition definition,
                     MutableAttributeMap input)

Called immediately after a start event is signaled, indicating a new session of the flow is starting but has not yet entered its start state. An exception may be thrown from this method to veto the start operation. Any type of runtime exception can be used for this purpose.

Parameters:

context - the source of the event

definition - the flow for which a new session is starting

input - a mutable input map to the starting flow session

sessionStarted

void sessionStarted(RequestContext context,
                    FlowSession session)

Called when a new flow session has started. At this point the start state has been entered.

Parameters:

context - the source of the event

eventSignaled

void eventSignaled(RequestContext context,
                   Event event)

Called when an event is signaled in the current state, but prior to any state transition.

Parameters:

context - the source of the event

event - the event that occured

stateEntering

void stateEntering(RequestContext context,
                   StateDefinition state)
                   throws EnterStateVetoException

Called when a state transitions, after the transition is matched but before the transition occurs.

Parameters:

context - the source of the event

state - the proposed state to transition to

Throws:

EnterStateVetoException - when entering the state is not allowed

stateEntered

void stateEntered(RequestContext context,
                  StateDefinition previousState,
                  StateDefinition state)

Called when a state transitions, after the transition occured.

Parameters:

context - the source of the event

previousState - from state of the transition

state - to state of the transition

paused

void paused(RequestContext context,
            ViewSelection selectedView)

Called when a flow execution is paused, for instance when it is waiting for user input (after event processing).

Parameters:

context - the source of the event

selectedView - the view that will display

resumed

void resumed(RequestContext context)

Called after a flow execution is successfully reactivated after pause (but before event processing).

Parameters:

context - the source of the event

sessionEnding

void sessionEnding(RequestContext context,
                   FlowSession session,
                   MutableAttributeMap output)

Called when the active flow execution session has been asked to end but before it has ended.

Parameters:

context - the source of the event

session - the current active session that is ending

output - the flow output produced by the ending session, this map may be modified by this listener to affect the output returned

sessionEnded

void sessionEnded(RequestContext context,
                  FlowSession session,
                  AttributeMap output)

Called when a flow execution session ends. If the ended session was the root session of the flow execution, the entire flow execution also ends.

Parameters:

context - the source of the event

session - ending flow session

output - final, unmodifiable output returned by the ended session

exceptionThrown

void exceptionThrown(RequestContext context,
                     FlowExecutionException exception)

Called when an exception is thrown during a flow execution, before the exception is handled by any registered handler.

Parameters:

context - the source of the exception

exception - the exception that occurred