001 /* MBeanServerFactory.java -- Manages server instances.
002 Copyright (C) 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package javax.management;
039
040 import gnu.classpath.SystemProperties;
041
042 import java.util.ArrayList;
043 import java.util.HashMap;
044 import java.util.Iterator;
045 import java.util.Map;
046
047 import javax.management.loading.ClassLoaderRepository;
048
049 /**
050 * <p>
051 * Creates and maintains a set of {@link MBeanServer} instances.
052 * Server instances, as of JMX 1.2, are created using a subclass
053 * of {@link MBeanServerBuilder}. The exact class used is controlled
054 * by the property <code>javax.management.builder.initial</code>,
055 * and allows the instances created by {@link MBeanServerBuilder}
056 * to be wrapped, thus providing additional functionality.
057 * </p>
058 * <p>
059 * The property is used as follows:
060 * </p>
061 * <ol>
062 * <li>If the property has no value, then an instance of
063 * {@link MBeanServerBuilder} is used.</li>
064 * <li>If a value is given, then:
065 * <ol>
066 * <li>The class is loaded using
067 * <code>Thread.currentThread().getContextClassLoader()</code>, or,
068 * if this is <code>null</code>, by <code>Class.forName()</code>.</li>
069 * <li><code>Class.newInstance()</code> is used to create an instance
070 * of the class. The class must be public and have a public empty
071 * constructor. If an exception is thrown, it is propogated as
072 * a {@link JMRuntimeException} and no new server instances may be
073 * created until the property is set to a valid value.</li>
074 * </ol></li>
075 * <li>The value is checked on each successive request for a server.
076 * If it differs from the class of the existing instance of
077 * {@link MBeanServerBuilder}, then the value is used to create
078 * a new instance.</li>
079 * </ol>
080 */
081 public class MBeanServerFactory
082 {
083
084 /**
085 * The last builder instance.
086 */
087 private static MBeanServerBuilder builder;
088
089 /**
090 * The map of registered servers (identifiers to servers).
091 */
092 private static final Map<Object,MBeanServer> servers = new HashMap();
093
094 /**
095 * Private constructor to prevent instance creation.
096 */
097 private MBeanServerFactory() {}
098
099 /**
100 * Returns a server implementation using the default domain name
101 * of <code>"DefaultDomain"</code>. The default domain name is
102 * used when the domain name specified by the user is <code>null</code.
103 * A reference to the created server is retained, so that it can
104 * be retrieved at a later date using {@link #findMBeanServer}.
105 * Calling this method is equivalent to calling
106 * {@link createMBeanServer(String)} with a <code>null</code> value.
107 *
108 * @return a new {@link MBeanServer} instance.
109 * @throws SecurityException if a security manager exists and the
110 * caller's permissions don't imply {@link
111 * MBeanServerPermission(String)}("createMBeanServer")
112 * @throws JMRuntimeException if the property
113 * <code>javax.management.builder.initial</code>
114 * exists but names a class which either can not be
115 * instantiated or provides an implementation that returns
116 * <code>null</code> from either
117 * {@link MBeanServerBuilder#newMBeanServerDelegate()}
118 * or {@link MBeanServerBuilder#newMBeanServer()}
119 * @throws ClassCastException if the property
120 * <code>javax.management.builder.initial</code>
121 * exists but names a class which is not a subclass
122 * of {@link MBeanServerBuilder}.
123 * @see #createMBeanServer(String)
124 */
125 public static MBeanServer createMBeanServer()
126 {
127 return createMBeanServer(null);
128 }
129
130 /**
131 * Returns a server implementation using the default domain name
132 * given, or <code>"DefaultDomain"</code> if this is <code>null</code>.
133 * The default domain name is used when the domain name specified by
134 * the user is <code>null</code. A reference to the created server is
135 * retained, so that it can be retrieved at a later date using
136 * {@link #findMBeanServer}.
137 *
138 * @param domain the default domain name of the server.
139 * @return a new {@link MBeanServer} instance.
140 * @throws SecurityException if a security manager exists and the
141 * caller's permissions don't imply {@link
142 * MBeanServerPermission(String)}("createMBeanServer")
143 * @throws JMRuntimeException if the property
144 * <code>javax.management.builder.initial</code>
145 * exists but names a class which either can not be
146 * instantiated or provides an implementation that returns
147 * <code>null</code> from either
148 * {@link MBeanServerBuilder#newMBeanServerDelegate()}
149 * or {@link MBeanServerBuilder#newMBeanServer()}
150 * @throws ClassCastException if the property
151 * <code>javax.management.builder.initial</code>
152 * exists but names a class which is not a subclass
153 * of {@link MBeanServerBuilder}.
154 */
155 public static MBeanServer createMBeanServer(String domain)
156 {
157 SecurityManager sm = System.getSecurityManager();
158 if (sm != null)
159 sm.checkPermission(new MBeanServerPermission("createMBeanServer"));
160 MBeanServer server = createServer(domain);
161 try
162 {
163 ObjectName dn = new
164 ObjectName("JMImplementation:type=MBeanServerDelegate");
165 servers.put(server.getAttribute(dn, "MBeanServerId"), server);
166 }
167 catch (MalformedObjectNameException e)
168 {
169 throw (Error)
170 (new InternalError("Malformed delegate bean name.").initCause(e));
171 }
172 catch (MBeanException e)
173 {
174 throw (Error)
175 (new InternalError("Exception in getMBeanServerId().").initCause(e));
176 }
177 catch (AttributeNotFoundException e)
178 {
179 throw (Error)
180 (new InternalError("Could not find MBeanServerId attribute.").initCause(e));
181 }
182 catch (InstanceNotFoundException e)
183 {
184 throw (Error)
185 (new InternalError("Could not find the delegate bean.").initCause(e));
186 }
187 catch (ReflectionException e)
188 {
189 throw (Error)
190 (new InternalError("Could not call getMBeanServerId().").initCause(e));
191 }
192 return server;
193 }
194
195 /**
196 * Returns the specified server, or, if <code>id</code> is <code>null</code>,
197 * a list of all registered servers. A registered server is one that
198 * was created using {@link #createMBeanServer()} or
199 * {@link #createMBeanServer(String)} and has not yet been released
200 * using {@link releaseMBeanServer(MBeanServer)}.
201 *
202 * @param id the id of the server to retrieve, or <code>null</code>
203 * to return all servers.
204 * @return a list of {@link MBeanServer}s.
205 * @throws SecurityException if a security manager exists and the
206 * caller's permissions don't imply {@link
207 * MBeanServerPermission(String)}("findMBeanServer")
208 */
209 public static ArrayList<MBeanServer> findMBeanServer(String id)
210 {
211 SecurityManager sm = System.getSecurityManager();
212 if (sm != null)
213 sm.checkPermission(new MBeanServerPermission("findMBeanServer"));
214 if (id == null)
215 return new ArrayList(servers.values());
216 ArrayList<MBeanServer> list = new ArrayList<MBeanServer>();
217 MBeanServer server = servers.get(id);
218 if (server != null)
219 list.add(servers.get(id));
220 return list;
221 }
222
223 /**
224 * Returns the class loader repository used by the specified server.
225 * This is equivalent to calling {@link MBeanServer#getClassLoaderRepository()}
226 * on the given server.
227 *
228 * @param server the server whose class loader repository should be
229 * retrieved.
230 * @throws NullPointerException if <code>server</code> is <code>null</code>.
231 * @throws SecurityException if a security manager exists and the
232 * caller's permissions don't imply {@link
233 * MBeanPermission(String,String,ObjectName,String)
234 * <code>MBeanPermission(null, null, null,
235 * "getClassLoaderRepository")</code>
236 */
237 public static ClassLoaderRepository getClassLoaderRepository(MBeanServer server)
238 {
239 return server.getClassLoaderRepository();
240 }
241
242 /**
243 * Returns a server implementation using the default domain name
244 * of <code>"DefaultDomain"</code>. The default domain name is
245 * used when the domain name specified by the user is <code>null</code.
246 * No reference to the created server is retained, so the server is
247 * garbage collected when it is no longer used, but it can not be
248 * retrieved at a later date using {@link #findMBeanServer}.
249 * Calling this method is equivalent to calling
250 * {@link newMBeanServer(String)} with a <code>null</code> value.
251 *
252 * @return a new {@link MBeanServer} instance.
253 * @throws SecurityException if a security manager exists and the
254 * caller's permissions don't imply {@link
255 * MBeanServerPermission(String)}("newMBeanServer")
256 * @throws JMRuntimeException if the property
257 * <code>javax.management.builder.initial</code>
258 * exists but names a class which either can not be
259 * instantiated or provides an implementation that returns
260 * <code>null</code> from either
261 * {@link MBeanServerBuilder#newMBeanServerDelegate()}
262 * or {@link MBeanServerBuilder#newMBeanServer()}
263 * @throws ClassCastException if the property
264 * <code>javax.management.builder.initial</code>
265 * exists but names a class which is not a subclass
266 * of {@link MBeanServerBuilder}.
267 * @see #newMBeanServer(String)
268 */
269 public static MBeanServer newMBeanServer()
270 {
271 return newMBeanServer(null);
272 }
273
274 /**
275 * Returns a server implementation using the default domain name
276 * given, or <code>"DefaultDomain"</code> if this is <code>null</code>.
277 * The default domain name is used when the domain name specified by
278 * the user is <code>null</code. No reference to the created server is
279 * retained, so the server is garbage collected when it is no longer
280 * used, but it can not be retrieved at a later date using
281 * {@link #findMBeanServer}.
282 *
283 * @param domain the default domain name of the server.
284 * @return a new {@link MBeanServer} instance.
285 * @throws SecurityException if a security manager exists and the
286 * caller's permissions don't imply {@link
287 * MBeanServerPermission(String)}("newMBeanServer")
288 * @throws JMRuntimeException if the property
289 * <code>javax.management.builder.initial</code>
290 * exists but names a class which either can not be
291 * instantiated or provides an implementation that returns
292 * <code>null</code> from either
293 * {@link MBeanServerBuilder#newMBeanServerDelegate()}
294 * or {@link MBeanServerBuilder#newMBeanServer()}
295 * @throws ClassCastException if the property
296 * <code>javax.management.builder.initial</code>
297 * exists but names a class which is not a subclass
298 * of {@link MBeanServerBuilder}.
299 */
300 public static MBeanServer newMBeanServer(String domain)
301 {
302 SecurityManager sm = System.getSecurityManager();
303 if (sm != null)
304 sm.checkPermission(new MBeanServerPermission("newMBeanServer"));
305 return createServer(domain);
306 }
307
308 /**
309 * Common method to create a server for the {@link #createMBeanServer(String)}
310 * and {@link #newMBeanServer(String)} methods above.
311 *
312 * @param domain the default domain name of the server.
313 * @throws JMRuntimeException if the property
314 * <code>javax.management.builder.initial</code>
315 * exists but names a class which either can not be
316 * instantiated or provides an implementation that returns
317 * <code>null</code> from either
318 * {@link MBeanServerBuilder#newMBeanServerDelegate()}
319 * or {@link MBeanServerBuilder#newMBeanServer()}
320 * @throws ClassCastException if the property
321 * <code>javax.management.builder.initial</code>
322 * exists but names a class which is not a subclass
323 * of {@link MBeanServerBuilder}.
324 */
325 private static MBeanServer createServer(String domain)
326 {
327 if (domain == null)
328 domain = "DefaultDomain";
329 String builderClass =
330 SystemProperties.getProperty("javax.management.builder.initial");
331 if (builderClass == null)
332 {
333 if (builder == null ||
334 builder.getClass() != MBeanServerBuilder.class)
335 builder = new MBeanServerBuilder();
336 }
337 else if (!(builder != null &&
338 builderClass.equals(builder.getClass().getName())))
339 {
340 ClassLoader cl = Thread.currentThread().getContextClassLoader();
341 if (cl == null)
342 cl = MBeanServerFactory.class.getClassLoader();
343 try
344 {
345 Class bClass = Class.forName(builderClass, true, cl);
346 builder = (MBeanServerBuilder) bClass.newInstance();
347 }
348 catch (ClassNotFoundException e)
349 {
350 throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
351 + builderClass +
352 ", could not be found."))
353 .initCause(e);
354 }
355 catch (InstantiationException e)
356 {
357 throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
358 + builderClass +
359 ", could not be instantiated."))
360 .initCause(e);
361 }
362 catch (IllegalAccessException e)
363 {
364 throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
365 + builderClass +
366 ", could not be accessed."))
367 .initCause(e);
368 }
369 }
370 MBeanServerDelegate delegate = builder.newMBeanServerDelegate();
371 if (delegate == null)
372 throw new JMRuntimeException("A delegate could not be created.");
373 MBeanServer server = builder.newMBeanServer(domain, null, delegate);
374 if (server == null)
375 throw new JMRuntimeException("A server could not be created.");
376 return server;
377 }
378
379 /**
380 * Removes the reference to the specified server, thus allowing it to
381 * be garbage collected.
382 *
383 * @param server the server to remove.
384 * @throws IllegalArgumentException if a reference to the server is not
385 * held (i.e. it wasn't created by
386 * {@link #createMBeanServer(String)}
387 * or this method has already been called
388 * on it.
389 * @throws SecurityException if a security manager exists and the
390 * caller's permissions don't imply {@link
391 * MBeanServerPermission(String)}("releaseMBeanServer")
392 */
393 public static void releaseMBeanServer(MBeanServer server)
394 {
395 SecurityManager sm = System.getSecurityManager();
396 if (sm != null)
397 sm.checkPermission(new MBeanServerPermission("releaseMBeanServer"));
398 Iterator<MBeanServer> i = servers.values().iterator();
399 while (i.hasNext())
400 {
401 MBeanServer s = i.next();
402 if (server == s)
403 {
404 i.remove();
405 return;
406 }
407 }
408 throw new IllegalArgumentException("The server given is not referenced.");
409 }
410
411
412 }