001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     * 
010     *      http://www.apache.org/licenses/LICENSE-2.0
011     * 
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.oozie.workflow.lite;
019    
020    
021    import org.apache.oozie.workflow.WorkflowException;
022    import org.apache.oozie.util.ParamChecker;
023    import org.apache.oozie.ErrorCode;
024    
025    import java.util.ArrayList;
026    import java.util.List;
027    
028    /**
029     * Workflow lite start node definition.
030     */
031    public class StartNodeDef extends NodeDef {
032    
033        /**
034         * Reserved name fo the start node. <p/> It is an invalid token, it will never match an application node name.
035         */
036        public static final String START = "::start::";
037    
038        /**
039         * Default constructor.
040         */
041        public StartNodeDef() {
042        }
043    
044        /**
045         * Create a start node definition.
046         *
047         * @param transitionTo transition on workflow start.
048         */
049        public StartNodeDef(String transitionTo) {
050            super(START, null, StartNodeHandler.class, createList(ParamChecker.notEmpty(transitionTo, "transitionTo")));
051        }
052    
053        private static List<String> createList(String transition) {
054            List<String> list = new ArrayList<String>();
055            list.add(transition);
056            return list;
057        }
058    
059        /**
060         * Start node handler. <p/> It does an immediate transition to the transitionTo node.
061         */
062        public static class StartNodeHandler extends NodeHandler {
063    
064            public boolean enter(Context context) throws WorkflowException {
065                if (!context.getSignalValue().equals(StartNodeDef.START)) {
066                    throw new WorkflowException(ErrorCode.E0715, context.getSignalValue());
067                }
068                return true;
069            }
070    
071            public String exit(Context context) {
072                return context.getNodeDef().getTransitions().get(0);
073            }
074    
075            public void kill(Context context) {
076            }
077    
078            public void fail(Context context) {
079            }
080        }
081    
082    }