1 /*
2 * Copyright 1999-2001,2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.apache.commons.workflow.demo;
18
19
20 import java.io.File;
21 import org.apache.commons.digester.Digester;
22 import org.apache.commons.workflow.Activity;
23 import org.apache.commons.workflow.Context;
24 import org.apache.commons.workflow.ContextEvent;
25 import org.apache.commons.workflow.ContextListener;
26 import org.apache.commons.workflow.base.BaseContext;
27 import org.apache.commons.workflow.base.BaseRuleSet;
28 import org.apache.commons.workflow.core.CoreRuleSet;
29 import org.apache.commons.workflow.io.IoRuleSet;
30 import org.apache.commons.workflow.web.WebRuleSet;
31
32
33 /**
34 * <p>Demonstration program to illustrate how the Workflow Management System
35 * is utilized. It accepts a command line argument to an XML file that
36 * contains an <code><activity></code> to be parsed and then executed.
37 * If no file is specified, a default XML document will be utilized.</p>
38 *
39 * <p><strong>WARNING</strong> - This program is for illustration only while
40 * the workflow management system is being developed, and it will not be
41 * part of the final package. Indeed, much of its functionality (such as
42 * the parsing of XML files describing activities) will need to be encapsulated
43 * inside the system, in ways that support the per-namespace step definitions
44 * as outlined in the original proposal.</p>
45 *
46 * <p><strong>WARNING</strong> - This code depends on the version of Digester
47 * currently in SVN - the 1.0 released version will not work correctly with
48 * namespace prefixes.</p>
49 *
50 * <p><strong>WARNING</strong> - The namespace URLs in the example XML document
51 * are not official - they are simply used to satisfy the syntax requirements
52 * of the XML parser. Official namespace URIs <em>will</em> be required for a
53 * formal release of this technology, because that is key to the extensibility
54 * of Step implementations.</p>
55 *
56 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
57 * @author Craig R. McClanahan
58 */
59
60 public class Main implements ContextListener {
61
62
63 // ----------------------------------------------------------- Main Program
64
65
66 /**
67 * The main program for the demo.
68 *
69 * @param args Command line arguments
70 */
71 public static void main(String args[]) {
72
73 // Make sure there is a filename argument
74 if (args.length != 1) {
75 System.out.println("Usage: java org.apache.commons.workflow.demo.Main {XML-file}");
76 System.exit(1);
77 }
78
79 // Construct and utilize a new instance of this class
80 Main main = new Main();
81 main.process(args[0]);
82
83 }
84
85
86 // ----------------------------------------------------- Instance Variables
87
88
89 /**
90 * The Activity constructed by our Digester.
91 */
92 protected Activity activity = null;
93
94
95 /**
96 * The Digester used to process input files.
97 */
98 protected Digester digester = null;
99
100
101 // ------------------------------------------------------------ Constructor
102
103
104 /**
105 * Construct a new instance of this class to process input files.
106 */
107 public Main() {
108
109 super();
110 digester = createDigester();
111
112 }
113
114
115 // -------------------------------------------------------- Support Methods
116
117
118 /**
119 * <p>Create a Digester instance that knows how to parse activities using
120 * the <code>core</code> and <code>io</code> built-in Steps.</p>
121 *
122 * <p><strong>WARNING</strong> - This will ultimately be abstracted into
123 * a mechanism to register the set of rule definitions associated with
124 * a namespace.</p>
125 */
126 protected Digester createDigester() {
127
128 // Construct and configure a new Digester instance
129 Digester digester = new Digester();
130 // digester.setDebug(999);
131 digester.setNamespaceAware(true);
132 digester.setValidating(false);
133 digester.push(this);
134
135 // Add rules to recognize the built-in steps that we know about
136 BaseRuleSet brs = new BaseRuleSet();
137 digester.addRuleSet(brs);
138 digester.addRuleSet(new CoreRuleSet());
139 digester.addRuleSet(new IoRuleSet());
140
141 // Add a rule to register the Activity being created
142 digester.setRuleNamespaceURI(brs.getNamespaceURI());
143 digester.addSetNext("activity", "setActivity",
144 "org.apache.commons.workflow.Activity");
145
146 // Return the completed instance
147 return (digester);
148
149 }
150
151
152 /**
153 * Save the Activity that our Digester has constructed.
154 *
155 * @param activity The newly constructed Activity
156 */
157 public void setActivity(Activity activity) {
158
159 this.activity = activity;
160
161 }
162
163
164 /**
165 * Process the specified file.
166 *
167 * @param pathname Pathname of the specified XML file containing
168 * an activity definition
169 */
170 public void process(String pathname) {
171
172 // Parse the activity definition
173 try {
174 System.out.println("Main: Parsing activity file " + pathname);
175 digester.parse(new File(pathname));
176 } catch (Throwable t) {
177 t.printStackTrace(System.out);
178 return;
179 }
180
181 // Create a context and execute this activity
182 try {
183 System.out.println("Main: Executing parsed activity");
184 Context context = new BaseContext();
185 context.setActivity(activity);
186 context.addContextListener(this);
187 context.execute();
188 } catch (Throwable t) {
189 t.printStackTrace(System.out);
190 return;
191 }
192
193 }
194
195
196 // ------------------------------------------------ ContextListener Methods
197
198
199 /**
200 * Invoked immediately after execution of the related Activity has
201 * been completed normally, been suspended, or been aborted by
202 * the throwing of a StepException. The Step included in this event
203 * will be the last one to be executed.
204 *
205 * @param event The <code>ContextEvent</code> that has occurred
206 */
207 public void afterActivity(ContextEvent event) {
208
209 System.out.println("CL: afterActivity()");
210
211 }
212
213
214 /**
215 * Invoked immediately after the specified Step was executed.
216 *
217 * @param event The <code>ContextEvent</code> that has occurred
218 */
219 public void afterStep(ContextEvent event) {
220
221 System.out.println("CL: afterStep(" + event.getStep().getId() + ")");
222
223 }
224
225
226 /**
227 * Invoked immediately before execution of the related Activity has
228 * started. The Step included in this event will be the first one
229 * to be executed.
230 *
231 * @param event The <code>ContextEvent</code> that has occurred
232 */
233 public void beforeActivity(ContextEvent event) {
234
235 System.out.println("CL: beforeActivity()");
236
237 }
238
239
240 /**
241 * Invoked immediately before the specified Step is executed.
242 *
243 * @param event The <code>ContextEvent</code> that has occurred
244 */
245 public void beforeStep(ContextEvent event) {
246
247 System.out.println("CL: beforeStep(" + event.getStep().getId() + ")");
248
249 }
250
251
252 }