ComponentRegistry


1   /*
2    * (c) Rob Gordon 2005
3    */
4   package org.oddjob.arooa.registry;
5   
6   import java.util.HashMap  ;
7   import java.util.Iterator  ;
8   import java.util.Map  ;
9   
10  import org.apache.commons.beanutils.PropertyUtils;
11  import org.oddjob.arooa.ArooaException;
12  import org.oddjob.values.types.MapType;
13  
14  /**
15   * Register components by id and look them up by path. A ComponentRegistry is a
16   * hierarchy with child registries. The path identifies in the hierarchy where
17   * the component resides.
18   * 
19   * @author Rob Gordon.
20   */
21  public class ComponentRegistry {
22  
23      /** The serverId for this registry */
24      private final ServerId serverId;
25      
26      /** Contains the path to this registry. */
27      private Path path;
28  
29      /** Maps ids to Components */
30      private final Map  /*<String, Object>*/ ids = new HashMap  ();
31  
32      /** Maps components to ids. */
33      private final Map  /*<Object, String>*/ components = new HashMap  ();
34      
35      /** Object to child. The id is the id of the component in this registry
36       * which links to the child registry. The linking component will typically
37       * be a nested OddJob or a client Job. */
38      private final Map   children/*<Object, ComponentRegistry>*/ = new HashMap  ();
39  
40      /**
41       * Constructor for a local registry.
42       *
43       */
44      public ComponentRegistry() {
45          this(ServerId.local());
46      }
47      
48      /**
49       * Constructor for a registry that contains proxies
50       * for remote components on the give server.
51       * 
52       * @param serverId The ServerId.
53       */
54      public ComponentRegistry(ServerId serverId) {
55          if (serverId == null) {
56              throw new NullPointerException  ("serverId must not be null!");
57          }
58          this.serverId = serverId;
59          this.path = new Path();
60      }
61      
62      /**
63       * Get the serverId.
64       * 
65       * @return The serverId.
66       */
67      public ServerId getServerId() {
68          return serverId;
69      }
70      
71      /**
72       * Add a child ComponentRegistry to this one.
73       * 
74       * @param child The child component registry.
75       * @param owner The component in this registry which owns the 
76       * child registry.
77       */
78      public void addChild(ComponentRegistry child, Object   owner) {
79          if (serverId.equals(child.serverId)) {
80              String   ownerId = getIdForComponent(owner);
81              Path childPath = path.addId(ownerId);
82              child.path = childPath;
83          }
84          else {
85              child.path = new Path();
86          }
87          children.put(owner, child);
88      }
89      
90      /**
91       * Remove a child ComponentRegistry.
92       * 
93       * @param owner The component in this registry which owns the 
94       * child registry.
95       */
96      public void removeChild(Object   owner) {
97          children.remove(owner);
98      }
99      
100     /**
101      * Get the component registry owned by the component which will
102      * probably either be an Oddjob or client job.
103      * 
104      * @param owner The owner component.
105      * @return A ComponentRegistry or null if the compnent
106      * doesn't own a registry.
107      */
108     public ComponentRegistry registryOwnedBy(Object   owner) {
109         return (ComponentRegistry) children.get(owner);
110     }
111 
112     /**
113      * Is the give component a registry owner?
114      * 
115      * @param component The component.
116      * @return true if it is, false otherwise.
117      */
118     public boolean isOwner(Object   component) {
119         return !(children.get(component) == null);
120     }
121     
122     /**
123      * Register an object. The id should not contain reserved characters.
124      * 
125      * @param id The id of the object.
126      * @param object The object.
127      */
128     public void register(String   id, Object   component) {
129         if (id == null) {
130             return;
131         }
132         if (id.indexOf(PropertyUtils.NESTED_DELIM) > -1
133                 || id.indexOf(PropertyUtils.INDEXED_DELIM) > -1 
134                 || id.indexOf(PropertyUtils.INDEXED_DELIM2) > -1 
135                 || id.indexOf(PropertyUtils.MAPPED_DELIM) > -1 
136                 || id.indexOf(PropertyUtils.MAPPED_DELIM2) > -1 
137                 || id.indexOf(Path.PATH_SEPARATOR) > -1) {
138             throw new ArooaException("Id contains a reserverd character.");
139         }
140         if (ids.containsKey(id)) {
141             throw new ArooaException("A component with id [" + id + "] is already registered");
142         }
143         ids.put(id, component);
144         components.put(component, id);
145     }
146     
147     /**
148      * Find the id for the given component.
149      * 
150      * @param component The component.
151      * @return The id or null if none can be found.
152      */
153     public String   getIdForComponent(Object   component) {
154         return (String  ) components.get(component);
155     }
156     
157     /**
158      * Get an object for the given path.
159      * 
160      * @param path The path.
161      * @return An object or null if it hasn't been registered.
162      */
163     public Object   objectForPath(Path path) {
164         if (path == null) {
165             return null;
166         }
167         Path childPath  = path.getChildPath();
168         if (childPath == null) {
169             return null;
170         }
171         String   id = path.getId();
172         Object   component = ids.get(id); 
173         if (childPath.size() == 0) {
174             return component;
175         }
176         ComponentRegistry child = 
177             (ComponentRegistry) children.get(component);
178         if (child == null) {
179             return null;
180         }
181         return child.objectForPath(childPath);
182     }
183     
184     /**
185      * Find the object from the possible addresses that could identify it. If
186      * there are several paths to the object (which can happen if the original object
187      * is accessable via several servers), the object with the shortest path is
188      * returned.
189      * 
190      * @param addresses The possible addresses of the component.
191      * @return The componen or null if none of the addresses are accessable.
192      */
193     public Object   objectForAddress(Address address) {
194         if (address == null) {
195             return null;
196         }
197         ComponentRegistry registry = registryForServer(address.getServerId());
198         if (registry == null) {
199                 return null;
200         }
201         Path relativePath = registry.path.relativeTo(address.getPath());
202         return registry.objectForPath(relativePath);
203     }
204 
205     /**
206      * Get the path to a given component that may or may not be
207      * in this registries hierarchy.
208      * 
209      * @param component The component.
210      * @return The path or null if it can't be found.
211      */
212     public Path pathForObject(Object   component) {
213         if (component == null) {
214             throw new NullPointerException  ("Component must not be null!");
215         }
216         return pathToComponent(new Path(), component);
217     }
218     
219     /**
220      * Helper funtion to find a path to a component.
221      * 
222      * @param existing The current path being built up in this recursive call.
223      * @param component The componet being searched for.
224      * 
225      * @return The path relative to this registry or null if it is
226      * is not acessable.
227      */
228     Path pathToComponent(Path existing, Object   component) {
229         String   id = getIdForComponent(component); 
230         if (id != null) {
231             return existing.addId(id);
232         }
233         // go round all the child registries recursing down until we find a
234         // registry for our component.
235         for (Iterator   it = children.entrySet().iterator(); it.hasNext();) {
236             Map.Entry   entry = (Map.Entry  ) it.next();
237             Object   childComponent = entry.getKey();
238             String   childId = (String  ) components.get(childComponent);
239             if (childId == null) {
240                 // a registry owner without an id - so no path downwards
241                 // from here.
242                 return null;
243             }
244             ComponentRegistry child = (ComponentRegistry) entry.getValue();
245             Path result = child.pathToComponent(
246                     existing.addId(childId), component);
247             if (result != null) {
248                 return result;
249             }
250         }
251         return null;
252     }
253     
254     /**
255      * Helper funtion to convert a path for a different server into the
256      * path to that servers client from this registry.
257      * 
258      * @param existing The current path being built up in this recursive call.
259      * @param serverId The server id for this current path.
260      * 
261      * @return The path relative to the other server or null if the other server
262      * is not acessable.
263      */
264     ComponentRegistry registryForServer(ServerId serverId) {
265         if (this.serverId.equals(serverId)) {
266             return this;
267         }
268         // go round all the child registries recursing down until we find a
269         // registry for the server.
270         for (Iterator   it = children.entrySet().iterator(); it.hasNext();) {
271             Map.Entry   entry = (Map.Entry  ) it.next();
272             ComponentRegistry child = (ComponentRegistry) entry.getValue();
273             ComponentRegistry result = child.registryForServer(serverId);
274             if (result != null) {
275                 return result;
276             }
277         }
278         return null;
279     }
280     
281     /**
282      * Get the possible addresses for a given component in this registry.
283      * 
284      * @param object The component.
285      * @return The possible addresses or null if the object is not registered
286      * in this registry.
287      */
288     public Address addressForObject(Object   object) {
289         String   id = (String  ) components.get(object); 
290         if (id == null) {
291             return null;
292         }
293         return new Address(serverId, 
294                 path.addId(id));
295     }
296         
297     /**
298      * Helper funtion to find a registry for a component.
299      * 
300      * @param existing The current path being built up in this recursive call.
301      * @param component The componet being searched for.
302      * 
303      * @return The path relative to this registry or null if it is
304      * is not acessable.
305      */
306     ComponentRegistry registryForComponent(Object   component) {
307         String   id = getIdForComponent(component); 
308         if (id != null) {
309             return this;
310         }
311         // go round all the child registries recursing down until we find a
312         // registry for our component.
313         for (Iterator   it = children.entrySet().iterator(); it.hasNext();) {
314             Map.Entry   entry = (Map.Entry  ) it.next();
315             Object   childComponent = entry.getKey();
316             String   childId = (String  ) components.get(childComponent);
317             if (childId == null) {
318                 // a registry owner without an id - so no path downwards
319                 // from here.
320                 return null;
321             }
322             ComponentRegistry child = (ComponentRegistry) entry.getValue();
323             ComponentRegistry result = child.registryForComponent(component);
324             if (result != null) {
325                 return result;
326             }
327         }
328         return null;
329     }
330     
331     
332     /**
333      * Remove a component from the registry if it exists.
334      * 
335      * @param component The compnent.
336      */
337     public void remove(Object   component) {
338         String   id = (String  ) components.remove(component);
339         ids.remove(id);
340         children.remove(component);
341     }
342 
343     /**
344      * Get the number of child registries for this registry.
345      * 
346      * @return The number of child registries.
347      */
348     public int childCount() {
349         return children.size();
350     }
351     
352     /*
353      *  (non-Javadoc)
354      * @see java.lang.Object#toString()
355      */
356     public String   toString() {
357         StringBuffer   buf = new StringBuffer  ();
358         buf.append("ComponentRegistry, ids [" + ids.size() + "], children [" + children.size() + "]");
359         buf.append('\n');
360         buf.append(MapType.propertiesFrom(ids));
361         return buf.toString();
362     }
363 }
364
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