org.springframework.webflow.execution.repository.impl

Class DefaultFlowExecutionRepository

java.lang.Object

org.springframework.webflow.execution.repository.support.AbstractFlowExecutionRepository

org.springframework.webflow.execution.repository.snapshot.AbstractSnapshottingFlowExecutionRepository

org.springframework.webflow.execution.repository.impl.DefaultFlowExecutionRepository

All Implemented Interfaces:

FlowExecutionKeyFactory, FlowExecutionRepository

public class DefaultFlowExecutionRepository
extends AbstractSnapshottingFlowExecutionRepository

The default flow execution repository implementation. Takes one to max flow execution snapshots, where each snapshot represents a copy of a FlowExecution taken at a point in time. Snapshots are created via a FlowExecutionSnapshotFactory and that may or may not involve creating a copy of a flow execution through Java serialization. In particular when the flow-execution-repository element is configured with max-execution-snapshots="0", creating snapshot copies is effectively turned off.

The set of active flow executions are managed by a ConversationManager implementation, which this repository delegates to.

This repository is responsible for:

• Beginning a new Conversation when a FlowExecution is assigned a persistent key. Each conversation is assigned a unique conversation id which forms one part of the flow execution key.
• Taking execution snapshots to persist flow execution state. A snapshot is a copy of the execution created at a point in time that can be restored and continued. Snapshotting supports users going back in their browser to continue their flow execution from a previoius point.
• Ending conversations when flow executions end.

This repository implementation also provides support for execution invalidation after completion, where once a logical flow execution completes, it and all of its snapshots are removed. This cleans up memory and prevents the possibility of duplicate submission after completion.

Author:

Keith Donald

Field Summary

Fields inherited from class org.springframework.webflow.execution.repository.support.AbstractFlowExecutionRepository

logger

Constructor Summary

Constructors

Constructor and Description
DefaultFlowExecutionRepository(ConversationManager conversationManager, FlowExecutionSnapshotFactory snapshotFactory) Create a new default flow execution repository using the given state restorer, conversation manager, and snapshot factory.

Method Summary

Modifier and Type	Method and Description
protected FlowExecutionSnapshotGroup	createFlowExecutionSnapshotGroup()
FlowExecution	getFlowExecution(FlowExecutionKey key) Return the FlowExecution indexed by the provided key.
int	getMaxSnapshots() Returns the max number of snapshots allowed per flow execution by this repository.
protected FlowExecutionSnapshotGroup	getSnapshotGroup(Conversation conversation) Returns the snapshot group associated with the governing conversation.
protected java.io.Serializable	nextSnapshotId(java.io.Serializable executionId) The next snapshot id to use for a FlowExecution instance.
void	putFlowExecution(FlowExecution flowExecution) Place the FlowExecution in this repository under the provided key.
void	removeAllFlowExecutionSnapshots(FlowExecution execution) Remove all snapshots associated with the flow execution from storage, invalidating all history.
void	removeFlowExecutionSnapshot(FlowExecution execution) Remove the snapshot that was used to restore this flow execution, discarding it for future use.
void	setMaxSnapshots(int maxSnapshots) Sets the maximum number of snapshots allowed per flow execution by this repository.
void	updateFlowExecutionSnapshot(FlowExecution execution) Capture the current state of the flow execution by updating its snapshot in storage.

Methods inherited from class org.springframework.webflow.execution.repository.snapshot.AbstractSnapshottingFlowExecutionRepository

getSnapshotFactory, getSnapshotId, putConversationScope, restoreFlowExecution, snapshot

Methods inherited from class org.springframework.webflow.execution.repository.support.AbstractFlowExecutionRepository

assertKeySet, createConversationParameters, getAlwaysGenerateNewNextKey, getConversation, getConversation, getConversationManager, getKey, getLock, parseFlowExecutionKey, removeFlowExecution, setAlwaysGenerateNewNextKey

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DefaultFlowExecutionRepository

public DefaultFlowExecutionRepository(ConversationManager conversationManager,
                                      FlowExecutionSnapshotFactory snapshotFactory)

Create a new default flow execution repository using the given state restorer, conversation manager, and snapshot factory.

Parameters:

conversationManager - the conversation manager to use

snapshotFactory - the flow execution snapshot factory to use

Method Detail

getMaxSnapshots

public int getMaxSnapshots()

Returns the max number of snapshots allowed per flow execution by this repository.

setMaxSnapshots

public void setMaxSnapshots(int maxSnapshots)

Sets the maximum number of snapshots allowed per flow execution by this repository. Use -1 for unlimited. The default is 30.

nextSnapshotId

protected java.io.Serializable nextSnapshotId(java.io.Serializable executionId)

Description copied from class: AbstractFlowExecutionRepository

The next snapshot id to use for a FlowExecution instance. Called when getting a flow execution key.

Specified by:

nextSnapshotId in class AbstractFlowExecutionRepository

Returns:

the id of the flow execution

getFlowExecution

public FlowExecution getFlowExecution(FlowExecutionKey key)

Description copied from interface: FlowExecutionRepository

Return the FlowExecution indexed by the provided key. The returned flow execution represents the restored state of an executing flow from a point in time. This should be called to resume a persistent flow execution. Before calling this method, you should acquire the lock for the keyed flow execution.

Specified by:

getFlowExecution in interface FlowExecutionRepository

Specified by:

getFlowExecution in class AbstractFlowExecutionRepository

Parameters:

key - the flow execution key

Returns:

the flow execution, fully hydrated and ready to resume

putFlowExecution

public void putFlowExecution(FlowExecution flowExecution)

Description copied from interface: FlowExecutionRepository

Place the FlowExecution in this repository under the provided key. This should be called to save or update the persistent state of an active (but paused) flow execution. Before calling this method, you should acquire the lock for the keyed flow execution.

Specified by:

putFlowExecution in interface FlowExecutionRepository

Specified by:

putFlowExecution in class AbstractFlowExecutionRepository

Parameters:

flowExecution - the flow execution

updateFlowExecutionSnapshot

public void updateFlowExecutionSnapshot(FlowExecution execution)

Description copied from interface: FlowExecutionKeyFactory

Capture the current state of the flow execution by updating its snapshot in storage. Does nothing if the no key has been assigned or no snapshot has already been taken.

Parameters:

execution - the flow execution

removeFlowExecutionSnapshot

public void removeFlowExecutionSnapshot(FlowExecution execution)

Description copied from interface: FlowExecutionKeyFactory

Remove the snapshot that was used to restore this flow execution, discarding it for future use. Does nothing if the no key been assigned or no snapshot has been taken.

Parameters:

execution - the flow execution

removeAllFlowExecutionSnapshots

public void removeAllFlowExecutionSnapshots(FlowExecution execution)

Description copied from interface: FlowExecutionKeyFactory

Remove all snapshots associated with the flow execution from storage, invalidating all history. Does nothing if no key has been assigned or no snapshots have been taken.

Parameters:

execution - the flow execution

createFlowExecutionSnapshotGroup

protected FlowExecutionSnapshotGroup createFlowExecutionSnapshotGroup()

getSnapshotGroup

protected FlowExecutionSnapshotGroup getSnapshotGroup(Conversation conversation)

Returns the snapshot group associated with the governing conversation.

Parameters:

conversation - the conversation where the snapshot group is stored

Returns:

the snapshot group