org.springframework.webflow.execution.FlowSession Maven / Gradle / Ivy
/*
* Copyright 2002-2006 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;
import org.springframework.webflow.core.collection.MutableAttributeMap;
import org.springframework.webflow.definition.FlowDefinition;
import org.springframework.webflow.definition.StateDefinition;
/**
* A single, local instantiation of a {@link 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
* {@link #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 {@link FlowSessionStatus#CREATED} when a new execution
* is started.
*
* After passing through the {@link FlowSessionStatus#STARTING} status, the flow
* session is activated (about to be manipulated) and its status becomes
* {@link 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 {@link 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 {@link 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 {@link 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 FlowDefinition
* @see FlowExecution
* @see FlowSessionStatus
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public interface FlowSession {
/**
* Returns the flow definition backing this session.
*/
public FlowDefinition getDefinition();
/**
* Returns the current state of this flow session. This value changes as the
* flow executes.
*/
public StateDefinition getState();
/**
* Returns the current status of this flow session. This value changes as
* the flow executes.
*/
public FlowSessionStatus getStatus();
/**
* Return this session's local attributes; the basis for "flow scope" (flow
* session scope).
* @return the flow scope attributes
*/
public MutableAttributeMap getScope();
/**
* Returns the local "flash map". Attributes in this map are cleared out
* on the next event signaled in the flow execution, so they survive a refresh.
* @return the flash map
*/
public MutableAttributeMap getFlashMap();
/**
* Returns the parent flow session in the current flow execution, or
* null if there is no parent flow session.
*/
public FlowSession getParent();
/**
* Returns whether this flow session is the root flow session in the ongoing
* flow execution. The root flow session does not have a parent flow
* session.
*/
public boolean isRoot();
}