Source for java.beans.beancontext.BeanContextServices

   1: /* java.beans.beancontext.BeanContextServices
   2:    Copyright (C) 1999 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.beans.beancontext;
  40: 
  41: import java.util.Iterator;
  42: import java.util.TooManyListenersException;
  43: 
  44: /**
  45:  * Allows a <code>BeanContext</code> to provide services to its children.
  46:  *
  47:  * @specnote it is unclear whether a <code>BeanContextServices</code>
  48:  *           should delegate unhandled requests to parents.  I assume so.
  49:  * @author John Keiser
  50:  * @since 1.2
  51:  */
  52: 
  53: public interface BeanContextServices
  54:   extends BeanContext, BeanContextServicesListener
  55: {
  56:   /**
  57:    * Register a service to make it available to others.
  58:    * This class may refuse to add the service based on whatever
  59:    * information it can gather, including whether the service
  60:    * provider is trusted.
  61:    *
  62:    * @param serviceClass the service class.
  63:    * @param provider the factory that will actually provide the service.
  64:    * @return whether the service was added or not.
  65:    */
  66:   boolean addService (Class serviceClass,
  67:                              BeanContextServiceProvider provider);
  68: 
  69:   /**
  70:    * Make it so that no one else can use this service.
  71:    * <P>
  72:    *
  73:    * If <code>revokeNow</code> is <code>false</code>, the only
  74:    * effect of this method is to make all subsequent calls to
  75:    * <code>getService()</code> on this service class fail.
  76:    * <P>
  77:    *
  78:    * If it is <code>true</code>, a message is also sent out to all
  79:    * listeners on the service and all references to it are released.
  80:    *
  81:    * @param serviceClass the service class to revoke.
  82:    * @param provider the service provider providing the service class.
  83:    * @param revokeNow whether to release all current references to
  84:    *        the service.
  85:    */
  86:   void revokeService (Class serviceClass,
  87:                              BeanContextServiceProvider provider,
  88:                              boolean revokeNow);
  89: 
  90:   /**
  91:    * Release your copy of this service.
  92:    * <P>
  93:    *
  94:    * If all copies of the service's class have been relinquished by
  95:    * the requestor, the <code>BeanContextServiceRevokedListener</code>
  96:    * previously registered by <code>getService()</code> will be
  97:    * unregistered.
  98:    *
  99:    * @param requestorChild the original <code>BeanContextChild</code>
 100:    *        requesting the service.
 101:    * @param requestor the original requestor of the service.
 102:    * @param service the service to relinquish
 103:    * @see #getService(java.beans.beancontext.BeanContextChild,java.lang.Object,java.lang.Class,java.lang.Object,java.beans.beancontext.BeanContextServiceRevokedListener)
 104:    */
 105:   void releaseService (BeanContextChild requestorChild, Object requestor,
 106:                               Object service);
 107: 
 108:   /**
 109:    * Get a service from this <code>BeanContextServices</code>.
 110:    * <P>
 111:    *
 112:    * The specified listener will be registered to receive a
 113:    * revocation notice for the specified serviceClass.  One
 114:    * notification per service class per requestor object will be
 115:    * sent.
 116:    * <P>
 117:    *
 118:    * The listener will be unregistered when all services that were
 119:    * obtained by that requestor for that service class are released.
 120:    * <P>
 121:    *
 122:    * If the requested service class is not available, or if this
 123:    * <code>BeanContextServices</code> object chooses not honor the
 124:    * request because the service class has been revoked or for some
 125:    * other reason, then this method will return <code>null</code>.
 126:    * <P>
 127:    *
 128:    * This method may throw unchecked exceptions, so watch out.
 129:    *
 130:    * @specnote it is not specified what happens when two subsequent
 131:    *           calls are made to <code>getService()</code> with the
 132:    *           same requestor object and service class but different
 133:    *           listeners.  Which listener is to be notified?
 134:    *
 135:    * @param requestorChild the <code>BeanContextChild</code>
 136:    *        associated with the requestor.  Typically this will be
 137:    *        the same as the requestor itself, but since any
 138:    *        <code>Object</code>, even one outside the hierarchy, may
 139:    *        make a request, this parameter is necessary.  Only weak
 140:    *        references to this will be retained, and it will never
 141:    *        be changed, only queried in a read-only manner.
 142:    * @param requestor the actual requestor of the service.  Only
 143:    *        weak references to this will be retained, and it will
 144:    *        never be changed, only queried in a read-only manner.
 145:    * @param serviceClass the <code>Class</code> of the service being
 146:    *        requested.
 147:    * @param serviceSelector a parameter to customize the service
 148:    *        returned with.
 149:    * @param listener a listener that will be notified if the service
 150:    *        being requested is revoked.
 151:    * @return an instance of <code>serviceClass</code> (such that
 152:    *        <code>instanceof</code> serviceClass is true), or
 153:    *        <code>null</code>.
 154:    */
 155:   Object getService (BeanContextChild requestorChild, Object requestor,
 156:                             Class serviceClass, Object serviceSelector,
 157:                             BeanContextServiceRevokedListener listener)
 158:     throws TooManyListenersException;
 159: 
 160:   /**
 161:    * Get a list of all service classes supported.
 162:    * <P>
 163:    *
 164:    * This method must synchronize on
 165:    * <code>BeanContext.globalHierarchyLock</code>.
 166:    *
 167:    * @return a list of all service classes supported.
 168:    * @see java.beans.beancontext.BeanContext#globalHierarchyLock
 169:    */
 170:   Iterator getCurrentServiceClasses ();
 171: 
 172:   /**
 173:    * Get a list of valid service selectors for the specified service class.
 174:    * <P>
 175:    *
 176:    * If the specified service class does not have a finite number of
 177:    * valid service selectors, it should return <code>null</code>.
 178:    * If it takes a general <code>Integer</code> parameter, for
 179:    * example, you may as well return <code>null</code> or the poor
 180:    * soul who called this method will be iterating all day.
 181:    * <P>
 182:    *
 183:    * If it has no valid service selectors, it should still return an empty
 184:    * <code>Iterator</code>.
 185:    *
 186:    * @param serviceClass the service class to get selectors for.
 187:    * @return a list of valid service selectors for the service
 188:    *         class, or <code>null</code>.
 189:    */
 190:   Iterator getCurrentServiceSelectors (Class serviceClass);
 191: 
 192:   /**
 193:    * Tell whether the specified service class is available.
 194:    * Iff getService() could return a non-null value for the
 195:    * specified service, this method will return <code>true</code>.
 196:    *
 197:    * @param serviceClass the service class to check on.
 198:    * @return whether the specified service class is available.
 199:    */
 200:   boolean hasService (Class serviceClass);
 201: 
 202:   /**
 203:    * Add a listener on all adds and removes of services.
 204:    * @param listener the listener to add.
 205:    */
 206:   void addBeanContextServicesListener (BeanContextServicesListener listener);
 207: 
 208:   /**
 209:    * Remove a listener on all adds and removes of services.
 210:    * @specnote it is not certain whether this should remove this
 211:    *           listener if it was specified in
 212:    *           <code>getService()</code>.
 213:    * @param listener the listener to add.
 214:    */
 215:   void removeBeanContextServicesListener (BeanContextServicesListener listener);
 216: }