001 /*
002 * Copyright 1999-2001,2004 The Apache Software Foundation.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package org.apache.commons.workflow.base;
018
019
020 import org.apache.commons.workflow.Activity;
021 import org.apache.commons.workflow.Context;
022 import org.apache.commons.workflow.Owner;
023 import org.apache.commons.workflow.Step;
024 import org.apache.commons.workflow.StepException;
025
026
027 /**
028 * <p><strong>BaseStep</strong> is a convenient base class for more sophisticated
029 * <code>Step</code> implementations. It includes management of the static
030 * relationships of Steps to each other, and to their owning Activity, but
031 * requires the implementation to provide an <code>execute()</code> method.
032 *
033 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
034 * @author Craig R. McClanahan
035 */
036
037 public abstract class BaseStep implements Step {
038
039
040 // ----------------------------------------------------- Instance Variables
041
042
043 /**
044 * The unique identifier (within this Activity) of this Step.
045 */
046 protected String id = null;
047
048
049 /**
050 * The next Step in our associated Activity.
051 */
052 protected Step nextStep = null;
053
054
055 /**
056 * The Activity or Block that owns this Step.
057 */
058 protected Owner owner = null;
059
060
061
062 /**
063 * The previous Step in our associated Activity.
064 */
065 protected Step previousStep = null;
066
067
068
069 // ------------------------------------------------------------- Properties
070
071
072 /**
073 * Return the unique identifier (within this Activity or Block)
074 * of this Step.
075 */
076 public String getId() {
077
078 return (this.id);
079
080 }
081
082
083 /**
084 * Set the unique identifier (within this Activity or Block)
085 * of this Step.
086 *
087 * @param id The new unique identifier
088 */
089 public void setId(String id) {
090
091 this.id = id;
092
093 }
094
095
096 /**
097 * Return the next Step in our associated Activity or Block.
098 */
099 public Step getNextStep() {
100
101 return (this.nextStep);
102
103 }
104
105
106 /**
107 * Set the next Step in our associated Activity or Block.
108 *
109 * @param nextStep The new next Step
110 */
111 public void setNextStep(Step nextStep) {
112
113 this.nextStep = nextStep;
114
115 }
116
117
118 /**
119 * Return the Activity or Block that owns this Step.
120 */
121 public Owner getOwner() {
122
123 return (this.owner);
124
125 }
126
127
128 /**
129 * Set the Activity or Block that owns this Step.
130 *
131 * @param owner The new owning Activity or Block
132 */
133 public void setOwner(Owner owner) {
134
135 this.owner = owner;
136
137 }
138
139
140 /**
141 * Return the previous Step in our associated Activity or Block.
142 */
143 public Step getPreviousStep() {
144
145 return (this.previousStep);
146
147 }
148
149
150 /**
151 * Set the previous Step in our associated Activity or Block.
152 *
153 * @param previousStep The new previous Step
154 */
155 public void setPreviousStep(Step previousStep) {
156
157 this.previousStep = previousStep;
158
159 }
160
161
162 // --------------------------------------------------------- Public Methods
163
164
165 /**
166 * Perform the executable actions related to this Step, in the context of
167 * the specified Context.
168 *
169 * @param context The Context that is tracking our execution state
170 *
171 * @exception StepException if a processing error has occurred
172 */
173 public abstract void execute(Context context) throws StepException;
174
175
176 }