/*
* Copyright 2004-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.webflow.execution.repository;
import org.springframework.webflow.execution.FlowExecution;
import org.springframework.webflow.execution.FlowExecutionKey;
/**
* Central subsystem interface responsible for the saving and restoring of flow executions, where each flow execution
* represents a state of an active flow definition.
* <p>
* Flow execution repositories are responsible for managing the storage, restoration and removal of flow executions
* launched by clients of the Spring Web Flow system.
* <p>
* When placed in a repository a {@link FlowExecution} object representing the state of a flow at a point in time is
* indexed under a unique {@link FlowExecutionKey}.
*
* @see FlowExecution
* @see FlowExecutionKey
*
* @author Erwin Vervaet
* @author Keith Donald
*/
public interface FlowExecutionRepository {
/**
* Parse the string-encoded flow execution key into its object form. Essentially, the reverse of
* {@link FlowExecutionKey#toString()}.
* @param encodedKey the string encoded key
* @return the parsed flow execution key, the persistent identifier for exactly one flow execution
*/
public FlowExecutionKey parseFlowExecutionKey(String encodedKey) throws FlowExecutionRepositoryException;
/**
* Return the lock for the flow execution, allowing for the lock to be acquired or released. Caution: care should be
* made not to allow for a deadlock situation. If you acquire a lock make sure you release it when you are done. The
* general pattern for safely doing work against a locked conversation follows:
*
* <pre>
* FlowExecutionLock lock = repository.getLock(key);
* lock.lock();
* try {
* FlowExecution execution = repository.getFlowExecution(key);
* // do work
* } finally {
* lock.unlock();
* }
* </pre>
*
* @param key the identifier of the flow execution to lock
* @return the lock
* @throws FlowExecutionRepositoryException a problem occurred accessing the lock object
*/
public FlowExecutionLock getLock(FlowExecutionKey key) throws FlowExecutionRepositoryException;
/**
* Return the <code>FlowExecution</code> 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.
* @param key the flow execution key
* @return the flow execution, fully hydrated and ready to resume
* @throws FlowExecutionRepositoryException if no flow execution was indexed with the key provided
*/
public FlowExecution getFlowExecution(FlowExecutionKey key) throws FlowExecutionRepositoryException;
/**
* Place the <code>FlowExecution</code> 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.
* @param flowExecution the flow execution
* @throws FlowExecutionRepositoryException the flow execution could not be stored
*/
public void putFlowExecution(FlowExecution flowExecution) throws FlowExecutionRepositoryException;
/**
* Remove the flow execution from the repository. This should be called when the flow execution ends (is no longer
* active). Before calling this method, you should acquire the lock for the keyed flow execution.
* @param flowExecution the flow execution
* @throws FlowExecutionRepositoryException the flow execution could not be removed.
*/
public void removeFlowExecution(FlowExecution flowExecution) throws FlowExecutionRepositoryException;
}