/*
* 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.mvc.servlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.webflow.core.FlowException;
import org.springframework.webflow.core.collection.MutableAttributeMap;
import org.springframework.webflow.execution.FlowExecutionOutcome;
/**
* A controller helper used for customizing access to a <i>single</i> flow definition in a Servlet enviroment. This
* helper is used to:
* <ol>
* <li>Launch executions of that flow with data in the execution input map
* <li>Handle outcomes reached by that flow in a custom manner
* <li>Handle unhandled exceptions dealing with that flow in a custom manner.
* </ol>
* Such a handler can be visually thought of as a "flow reference" on a Garrett IA diagram. It holds a reference to the
* flow id to launch, how to provision its input, how to process its outcomes, and how to handle uncaught exceptions.
*
* @author Keith Donald
*/
public interface FlowHandler {
/**
* Returns the id of the flow handled by this handler. Used by a Controller to load the flow definition. Optional.
* @return the flow id, or null if the flow id should be determined by the caller
*/
public String getFlowId();
/**
* Creates the flow execution input map to pass to a new instance of the flow being started. Used by a Controller to
* launch the flow execution with the correct input.
* @param request the current request
* @return the input map, or null if the contents of the input map should be determined by the caller
*/
public MutableAttributeMap<Object> createExecutionInputMap(HttpServletRequest request);
/**
* Handles a specific flow execution outcome. Used by a Controller to get the location of the resource to redirect
* to after the outcome is handled.
* <p>
* The following prefixes are supported for qualifying the returned location string:
* <ul>
* <li>servletRelative: - the location is relative to the current servlet</li>
* <li>contextRelative: - the location is relative to the current web application</li>
* <li>serverRelative: - the location is relative to the server root</li>
* </ul>
* If the returned location is a path with no prefix, for example "/hotels/index", it is treated as relative to the
* current servlet by default. Fully qualified URLs beginning with http:// or https:// may also be returned.
* <p>
* For servlet-relative, context-relative, and server-relative URLs, a leading slash is optional.
*
* @param outcome the outcome that was reached
* @param request the current request
* @param response the current response
* @return the location of the new resource to redirect to, or null if the execution outcome was not handled and
* should be handled by the caller
*/
public String handleExecutionOutcome(FlowExecutionOutcome outcome, HttpServletRequest request,
HttpServletResponse response);
/**
* Handles a flow exception that was not handled by the Web Flow system. Used by a Controller to handle a specific
* type of exception dealing with this flow in a custom manner.
* @param e the unhandled exception originating from Spring Web Flow. May be thrown by the flow execution itself or
* the flow executor system if no execution could be restored.
* @param request the current request
* @param response the current response
* @return the location of the error resource to redirect to, or null if the execution outcome was not handled and
* should be handled by the caller
*/
public String handleException(FlowException e, HttpServletRequest request, HttpServletResponse response);
}