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    import org.apache.oozie.workflow.WorkflowException;
021    import org.apache.oozie.workflow.WorkflowInstance;
022    import org.apache.oozie.ErrorCode;
023    
024    import java.util.ArrayList;
025    import java.util.List;
026    
027    //TODO javadoc
028    public abstract class NodeHandler {
029    
030        public interface Context {
031    
032            public NodeDef getNodeDef();
033    
034            public String getExecutionPath();
035    
036            public String getParentExecutionPath(String executionPath);
037    
038            public String getSignalValue();
039    
040            public void setVar(String name, String value);
041    
042            public String getVar(String name);
043    
044            public void setTransientVar(String name, Object value);
045    
046            public Object getTransientVar(String name);
047    
048            public String createExecutionPath(String name);
049    
050            //can be called only from exit(), creation of execPaths is automatic
051            //when a handler returns more than one transition.
052            public void deleteExecutionPath();
053    
054            //must be used by multiExit
055            public String createFullTransition(String executionPath, String transition);
056    
057            public void killJob();
058    
059            public void completeJob();
060    
061            public LiteWorkflowInstance getProcessInstance();
062        }
063    
064        private static final String VISITED = "visited";
065    
066        public static String getLoopFlag(String nodeName) {
067            return nodeName + WorkflowInstance.NODE_VAR_SEPARATOR + VISITED;
068        }
069    
070        public void loopDetection(Context context) throws WorkflowException {
071            String flag = getLoopFlag(context.getNodeDef().getName());
072            if (context.getVar(flag) != null) {
073                throw new WorkflowException(ErrorCode.E0709, context.getNodeDef().getName());
074            }
075            context.setVar(flag, "true");
076        }
077    
078        // TRUE means immediate exit, false means has to be signal
079        public abstract boolean enter(Context context) throws WorkflowException;
080    
081        // the return list contains executionPath#transition, important for fork
082        public List<String> multiExit(Context context) throws WorkflowException {
083            List<String> transitions = new ArrayList<String>(1);
084            String transition = exit(context);
085            if (transition != null) {
086                transitions.add(context.createFullTransition(context.getExecutionPath(), transition));
087            }
088            return transitions;
089        }
090    
091    
092        public abstract String exit(Context context) throws WorkflowException;
093    
094        public void kill(Context context) {
095        }
096    
097        public void fail(Context context) {
098        }
099    }