001    /**
002     * Copyright (c) 2010 Yahoo! Inc. All rights reserved.
003     * Licensed under the Apache License, Version 2.0 (the "License");
004     * you may not use this file except in compliance with the License.
005     * You may obtain a copy of the License at
006     *
007     *   http://www.apache.org/licenses/LICENSE-2.0
008     *
009     *  Unless required by applicable law or agreed to in writing, software
010     *  distributed under the License is distributed on an "AS IS" BASIS,
011     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012     *  See the License for the specific language governing permissions and
013     *  limitations under the License. See accompanying LICENSE file.
014     */
015    package org.apache.oozie.workflow.lite;
016    
017    
018    import org.apache.oozie.workflow.WorkflowException;
019    import org.apache.oozie.util.ParamChecker;
020    import org.apache.oozie.ErrorCode;
021    
022    import java.util.ArrayList;
023    import java.util.List;
024    
025    /**
026     * Workflow lite start node definition.
027     */
028    public class StartNodeDef extends NodeDef {
029    
030        /**
031         * Reserved name fo the start node. <p/> It is an invalid token, it will never match an application node name.
032         */
033        public static final String START = "::start::";
034    
035        /**
036         * Default constructor.
037         */
038        public StartNodeDef() {
039        }
040    
041        /**
042         * Create a start node definition.
043         *
044         * @param transitionTo transition on workflow start.
045         */
046        public StartNodeDef(String transitionTo) {
047            super(START, null, StartNodeHandler.class, createList(ParamChecker.notEmpty(transitionTo, "transitionTo")));
048        }
049    
050        private static List<String> createList(String transition) {
051            List<String> list = new ArrayList<String>();
052            list.add(transition);
053            return list;
054        }
055    
056        /**
057         * Start node handler. <p/> It does an immediate transition to the transitionTo node.
058         */
059        public static class StartNodeHandler extends NodeHandler {
060    
061            public boolean enter(Context context) throws WorkflowException {
062                if (!context.getSignalValue().equals(StartNodeDef.START)) {
063                    throw new WorkflowException(ErrorCode.E0715, context.getSignalValue());
064                }
065                return true;
066            }
067    
068            public String exit(Context context) {
069                return context.getNodeDef().getTransitions().get(0);
070            }
071    
072            public void kill(Context context) {
073            }
074    
075            public void fail(Context context) {
076            }
077        }
078    
079    }