001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.activemq.jndi;
019
020import java.io.Serializable;
021import java.util.Collections;
022import java.util.HashMap;
023import java.util.Hashtable;
024import java.util.Iterator;
025import java.util.Map;
026import javax.naming.Binding;
027import javax.naming.CompositeName;
028import javax.naming.Context;
029import javax.naming.LinkRef;
030import javax.naming.Name;
031import javax.naming.NameClassPair;
032import javax.naming.NameNotFoundException;
033import javax.naming.NameParser;
034import javax.naming.NamingEnumeration;
035import javax.naming.NamingException;
036import javax.naming.NotContextException;
037import javax.naming.OperationNotSupportedException;
038import javax.naming.Reference;
039import javax.naming.spi.NamingManager;
040import org.slf4j.Logger;
041import org.slf4j.LoggerFactory;
042
043/**
044 * A read-only Context <p/> This version assumes it and all its subcontext are
045 * read-only and any attempt to modify (e.g. through bind) will result in an
046 * OperationNotSupportedException. Each Context in the tree builds a cache of
047 * the entries in all sub-contexts to optimise the performance of lookup.
048 * </p>
049 * <p>
050 * This implementation is intended to optimise the performance of lookup(String)
051 * to about the level of a HashMap get. It has been observed that the scheme
052 * resolution phase performed by the JVM takes considerably longer, so for
053 * optimum performance lookups should be coded like:
054 * </p>
055 * <code>
056 * Context componentContext = (Context)new InitialContext().lookup("java:comp");
057 * String envEntry = (String) componentContext.lookup("env/myEntry");
058 * String envEntry2 = (String) componentContext.lookup("env/myEntry2");
059 * </code>
060 * 
061 *  $Date: 2005/08/27 03:52:39 $
062 */
063@SuppressWarnings("unchecked")
064public class ReadOnlyContext implements Context, Serializable {
065    private static final Logger LOG = LoggerFactory.getLogger(ReadOnlyContext.class);
066    public static final String SEPARATOR = "/";
067    protected static final NameParser NAME_PARSER = new NameParserImpl();
068    private static final long serialVersionUID = -5754338187296859149L;
069
070    protected final Hashtable<String, Object> environment; // environment for this context
071    protected final Map<String, Object> bindings; // bindings at my level
072    protected final Map<String, Object> treeBindings; // all bindings under me
073
074    private boolean frozen;
075    private String nameInNamespace = "";
076
077    public ReadOnlyContext() {
078        environment = new Hashtable<String, Object>();
079        bindings = new HashMap<String, Object>();
080        treeBindings = new HashMap<String, Object>();
081    }
082
083    public ReadOnlyContext(Hashtable env) {
084        if (env == null) {
085            this.environment = new Hashtable<String, Object>();
086        } else {
087            this.environment = new Hashtable<String, Object>(env);
088        }
089        this.bindings = Collections.EMPTY_MAP;
090        this.treeBindings = Collections.EMPTY_MAP;
091    }
092
093    public ReadOnlyContext(Hashtable environment, Map<String, Object> bindings) {
094        if (environment == null) {
095            this.environment = new Hashtable<String, Object>();
096        } else {
097            this.environment = new Hashtable<String, Object>(environment);
098        }
099        this.bindings = new HashMap<String, Object>();
100        treeBindings = new HashMap<String, Object>();
101        if (bindings != null) {
102            for (Map.Entry<String, Object> binding : bindings.entrySet()) {
103                try {
104                    internalBind(binding.getKey(), binding.getValue());
105                } catch (Throwable e) {
106                    LOG.error("Failed to bind " + binding.getKey() + "=" + binding.getValue(), e);
107                }
108            }
109        }
110        frozen = true;
111    }
112
113    public ReadOnlyContext(Hashtable environment, Map bindings, String nameInNamespace) {
114        this(environment, bindings);
115        this.nameInNamespace = nameInNamespace;
116    }
117
118    protected ReadOnlyContext(ReadOnlyContext clone, Hashtable env) {
119        this.bindings = clone.bindings;
120        this.treeBindings = clone.treeBindings;
121        this.environment = new Hashtable<String, Object>(env);
122    }
123
124    protected ReadOnlyContext(ReadOnlyContext clone, Hashtable<String, Object> env, String nameInNamespace) {
125        this(clone, env);
126        this.nameInNamespace = nameInNamespace;
127    }
128
129    public void freeze() {
130        frozen = true;
131    }
132
133    boolean isFrozen() {
134        return frozen;
135    }
136
137    /**
138     * internalBind is intended for use only during setup or possibly by
139     * suitably synchronized superclasses. It binds every possible lookup into a
140     * map in each context. To do this, each context strips off one name segment
141     * and if necessary creates a new context for it. Then it asks that context
142     * to bind the remaining name. It returns a map containing all the bindings
143     * from the next context, plus the context it just created (if it in fact
144     * created it). (the names are suitably extended by the segment originally
145     * lopped off).
146     * 
147     * @param name
148     * @param value
149     * @return
150     * @throws javax.naming.NamingException
151     */
152    protected Map<String, Object> internalBind(String name, Object value) throws NamingException {
153        assert name != null && name.length() > 0;
154        assert !frozen;
155
156        Map<String, Object> newBindings = new HashMap<String, Object>();
157        int pos = name.indexOf('/');
158        if (pos == -1) {
159            if (treeBindings.put(name, value) != null) {
160                throw new NamingException("Something already bound at " + name);
161            }
162            bindings.put(name, value);
163            newBindings.put(name, value);
164        } else {
165            String segment = name.substring(0, pos);
166            assert segment != null;
167            assert !segment.equals("");
168            Object o = treeBindings.get(segment);
169            if (o == null) {
170                o = newContext();
171                treeBindings.put(segment, o);
172                bindings.put(segment, o);
173                newBindings.put(segment, o);
174            } else if (!(o instanceof ReadOnlyContext)) {
175                throw new NamingException("Something already bound where a subcontext should go");
176            }
177            ReadOnlyContext readOnlyContext = (ReadOnlyContext)o;
178            String remainder = name.substring(pos + 1);
179            Map<String, Object> subBindings = readOnlyContext.internalBind(remainder, value);
180            for (Iterator iterator = subBindings.entrySet().iterator(); iterator.hasNext();) {
181                Map.Entry entry = (Map.Entry)iterator.next();
182                String subName = segment + "/" + (String)entry.getKey();
183                Object bound = entry.getValue();
184                treeBindings.put(subName, bound);
185                newBindings.put(subName, bound);
186            }
187        }
188        return newBindings;
189    }
190
191    protected ReadOnlyContext newContext() {
192        return new ReadOnlyContext();
193    }
194
195    public Object addToEnvironment(String propName, Object propVal) throws NamingException {
196        return environment.put(propName, propVal);
197    }
198
199    public Hashtable<String, Object> getEnvironment() throws NamingException {
200        return (Hashtable<String, Object>)environment.clone();
201    }
202
203    public Object removeFromEnvironment(String propName) throws NamingException {
204        return environment.remove(propName);
205    }
206
207    public Object lookup(String name) throws NamingException {
208        if (name.length() == 0) {
209            return this;
210        }
211        Object result = treeBindings.get(name);
212        if (result == null) {
213            result = bindings.get(name);
214        }
215        if (result == null) {
216            int pos = name.indexOf(':');
217            if (pos > 0) {
218                String scheme = name.substring(0, pos);
219                Context ctx = NamingManager.getURLContext(scheme, environment);
220                if (ctx == null) {
221                    throw new NamingException("scheme " + scheme + " not recognized");
222                }
223                return ctx.lookup(name);
224            } else {
225                // Split out the first name of the path
226                // and look for it in the bindings map.
227                CompositeName path = new CompositeName(name);
228
229                if (path.size() == 0) {
230                    return this;
231                } else {
232                    String first = path.get(0);
233                    Object obj = bindings.get(first);
234                    if (obj == null) {
235                        throw new NameNotFoundException(name);
236                    } else if (obj instanceof Context && path.size() > 1) {
237                        Context subContext = (Context)obj;
238                        obj = subContext.lookup(path.getSuffix(1));
239                    }
240                    return obj;
241                }
242            }
243        }
244        if (result instanceof LinkRef) {
245            LinkRef ref = (LinkRef)result;
246            result = lookup(ref.getLinkName());
247        }
248        if (result instanceof Reference) {
249            try {
250                result = NamingManager.getObjectInstance(result, null, null, this.environment);
251            } catch (NamingException e) {
252                throw e;
253            } catch (Exception e) {
254                throw (NamingException)new NamingException("could not look up : " + name).initCause(e);
255            }
256        }
257        if (result instanceof ReadOnlyContext) {
258            String prefix = getNameInNamespace();
259            if (prefix.length() > 0) {
260                prefix = prefix + SEPARATOR;
261            }
262            result = new ReadOnlyContext((ReadOnlyContext)result, environment, prefix + name);
263        }
264        return result;
265    }
266
267    public Object lookup(Name name) throws NamingException {
268        return lookup(name.toString());
269    }
270
271    public Object lookupLink(String name) throws NamingException {
272        return lookup(name);
273    }
274
275    public Name composeName(Name name, Name prefix) throws NamingException {
276        Name result = (Name)prefix.clone();
277        result.addAll(name);
278        return result;
279    }
280
281    public String composeName(String name, String prefix) throws NamingException {
282        CompositeName result = new CompositeName(prefix);
283        result.addAll(new CompositeName(name));
284        return result.toString();
285    }
286
287    public NamingEnumeration list(String name) throws NamingException {
288        Object o = lookup(name);
289        if (o == this) {
290            return new ListEnumeration();
291        } else if (o instanceof Context) {
292            return ((Context)o).list("");
293        } else {
294            throw new NotContextException();
295        }
296    }
297
298    public NamingEnumeration listBindings(String name) throws NamingException {
299        Object o = lookup(name);
300        if (o == this) {
301            return new ListBindingEnumeration();
302        } else if (o instanceof Context) {
303            return ((Context)o).listBindings("");
304        } else {
305            throw new NotContextException();
306        }
307    }
308
309    public Object lookupLink(Name name) throws NamingException {
310        return lookupLink(name.toString());
311    }
312
313    public NamingEnumeration list(Name name) throws NamingException {
314        return list(name.toString());
315    }
316
317    public NamingEnumeration listBindings(Name name) throws NamingException {
318        return listBindings(name.toString());
319    }
320
321    public void bind(Name name, Object obj) throws NamingException {
322        throw new OperationNotSupportedException();
323    }
324
325    public void bind(String name, Object obj) throws NamingException {
326        throw new OperationNotSupportedException();
327    }
328
329    public void close() throws NamingException {
330        // ignore
331    }
332
333    public Context createSubcontext(Name name) throws NamingException {
334        throw new OperationNotSupportedException();
335    }
336
337    public Context createSubcontext(String name) throws NamingException {
338        throw new OperationNotSupportedException();
339    }
340
341    public void destroySubcontext(Name name) throws NamingException {
342        throw new OperationNotSupportedException();
343    }
344
345    public void destroySubcontext(String name) throws NamingException {
346        throw new OperationNotSupportedException();
347    }
348
349    public String getNameInNamespace() throws NamingException {
350        return nameInNamespace;
351    }
352
353    public NameParser getNameParser(Name name) throws NamingException {
354        return NAME_PARSER;
355    }
356
357    public NameParser getNameParser(String name) throws NamingException {
358        return NAME_PARSER;
359    }
360
361    public void rebind(Name name, Object obj) throws NamingException {
362        throw new OperationNotSupportedException();
363    }
364
365    public void rebind(String name, Object obj) throws NamingException {
366        throw new OperationNotSupportedException();
367    }
368
369    public void rename(Name oldName, Name newName) throws NamingException {
370        throw new OperationNotSupportedException();
371    }
372
373    public void rename(String oldName, String newName) throws NamingException {
374        throw new OperationNotSupportedException();
375    }
376
377    public void unbind(Name name) throws NamingException {
378        throw new OperationNotSupportedException();
379    }
380
381    public void unbind(String name) throws NamingException {
382        throw new OperationNotSupportedException();
383    }
384
385    private abstract class LocalNamingEnumeration implements NamingEnumeration {
386        private final Iterator i = bindings.entrySet().iterator();
387
388        public boolean hasMore() throws NamingException {
389            return i.hasNext();
390        }
391
392        public boolean hasMoreElements() {
393            return i.hasNext();
394        }
395
396        protected Map.Entry getNext() {
397            return (Map.Entry)i.next();
398        }
399
400        public void close() throws NamingException {
401        }
402    }
403
404    private class ListEnumeration extends LocalNamingEnumeration {
405        ListEnumeration() {
406        }
407
408        public Object next() throws NamingException {
409            return nextElement();
410        }
411
412        public Object nextElement() {
413            Map.Entry entry = getNext();
414            return new NameClassPair((String)entry.getKey(), entry.getValue().getClass().getName());
415        }
416    }
417
418    private class ListBindingEnumeration extends LocalNamingEnumeration {
419        ListBindingEnumeration() {
420        }
421
422        public Object next() throws NamingException {
423            return nextElement();
424        }
425
426        public Object nextElement() {
427            Map.Entry entry = getNext();
428            return new Binding((String)entry.getKey(), entry.getValue());
429        }
430    }
431}