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,
013 software distributed under the License is distributed on an
014 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 KIND, either express or implied. See the License for the
016 specific language governing permissions and limitations
017 under the License.
018 */
019 package org.apache.wiki.workflow;
020
021 import java.security.Principal;
022
023 /**
024 * AbstractStep subclass that executes instructions, uninterrupted, and results
025 * in an Outcome. Concrete classes only need to implement {@link Task#execute()}.
026 * When the execution step completes, <code>execute</code> must return
027 * {@link Outcome#STEP_COMPLETE}, {@link Outcome#STEP_CONTINUE} or
028 * {@link Outcome#STEP_ABORT}. Subclasses can add any errors by calling the
029 * helper method {@link AbstractStep#addError(String)}. The execute method should
030 * <em>generally</em> capture and add errors to the error list instead of
031 * throwing a WikiException.
032 * <p>
033 *
034 * @since 2.5
035 */
036 public abstract class Task extends AbstractStep
037 {
038 private static final long serialVersionUID = 4630293957752430807L;
039
040 private Step m_successor = null;
041
042 /**
043 * Protected constructor that creates a new Task with a specified message key.
044 * After construction, the protected method {@link #setWorkflow(Workflow)} should be
045 * called.
046 *
047 * @param messageKey
048 * the Step's message key, such as
049 * <code>decision.editPageApproval</code>. By convention, the
050 * message prefix should be a lower-case version of the Step's
051 * type, plus a period (<em>e.g.</em>, <code>task.</code>
052 * and <code>decision.</code>).
053 */
054 public Task( String messageKey )
055 {
056 super( messageKey );
057 super.addSuccessor( Outcome.STEP_COMPLETE, null );
058 super.addSuccessor( Outcome.STEP_ABORT, null );
059 }
060
061 /**
062 * Constructs a new instance of a Task, with an associated Workflow and
063 * message key.
064 *
065 * @param workflow
066 * the associated workflow
067 * @param messageKey
068 * the i18n message key
069 */
070 public Task( Workflow workflow, String messageKey )
071 {
072 this( messageKey );
073 setWorkflow( workflow );
074 }
075
076 /**
077 * Returns {@link SystemPrincipal#SYSTEM_USER}.
078 * @return the system principal
079 */
080 public final Principal getActor()
081 {
082 return SystemPrincipal.SYSTEM_USER;
083 }
084
085 /**
086 * Sets the successor Step to this one, which will be triggered if the Task
087 * completes successfully (that is, {@link Step#getOutcome()} returns
088 * {@link Outcome#STEP_COMPLETE}. This method is really a convenient
089 * shortcut for {@link Step#addSuccessor(Outcome, Step)}, where the first
090 * parameter is {@link Outcome#STEP_COMPLETE}.
091 *
092 * @param step
093 * the successor
094 */
095 public final synchronized void setSuccessor( Step step )
096 {
097 m_successor = step;
098 }
099
100 /**
101 * Identifies the next Step after this Task finishes successfully. This
102 * method will always return the value set in method
103 * {@link #setSuccessor(Step)}, regardless of the current completion state.
104 *
105 * @return the next step
106 */
107 public final synchronized Step getSuccessor()
108 {
109 return m_successor;
110 }
111
112 }