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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: }