217 lines
8.6 KiB
Java
217 lines
8.6 KiB
Java
/* java.beans.beancontext.BeanContextServices
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Copyright (C) 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.beans.beancontext;
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import java.util.Iterator;
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import java.util.TooManyListenersException;
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/**
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* Allows a <code>BeanContext</code> to provide services to its children.
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*
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* @specnote it is unclear whether a <code>BeanContextServices</code>
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* should delegate unhandled requests to parents. I assume so.
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* @author John Keiser
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* @since 1.2
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*/
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public interface BeanContextServices
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extends BeanContext, BeanContextServicesListener
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{
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/**
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* Register a service to make it available to others.
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* This class may refuse to add the service based on whatever
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* information it can gather, including whether the service
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* provider is trusted.
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*
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* @param serviceClass the service class.
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* @param provider the factory that will actually provide the service.
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* @return whether the service was added or not.
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*/
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boolean addService (Class serviceClass,
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BeanContextServiceProvider provider);
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/**
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* Make it so that no one else can use this service.
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* <P>
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*
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* If <code>revokeNow</code> is <code>false</code>, the only
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* effect of this method is to make all subsequent calls to
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* <code>getService()</code> on this service class fail.
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* <P>
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*
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* If it is <code>true</code>, a message is also sent out to all
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* listeners on the service and all references to it are released.
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*
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* @param serviceClass the service class to revoke.
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* @param provider the service provider providing the service class.
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* @param revokeNow whether to release all current references to
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* the service.
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*/
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void revokeService (Class serviceClass,
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BeanContextServiceProvider provider,
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boolean revokeNow);
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/**
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* Release your copy of this service.
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* <P>
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*
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* If all copies of the service's class have been relinquished by
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* the requestor, the <code>BeanContextServiceRevokedListener</code>
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* previously registered by <code>getService()</code> will be
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* unregistered.
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*
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* @param requestorChild the original <code>BeanContextChild</code>
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* requesting the service.
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* @param requestor the original requestor of the service.
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* @param service the service to relinquish
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* @see #getService(java.beans.beancontext.BeanContextChild,java.lang.Object,java.lang.Class,java.lang.Object,java.beans.beancontext.BeanContextServiceRevokedListener)
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*/
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void releaseService (BeanContextChild requestorChild, Object requestor,
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Object service);
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/**
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* Get a service from this <code>BeanContextServices</code>.
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* <P>
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*
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* The specified listener will be registered to receive a
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* revocation notice for the specified serviceClass. One
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* notification per service class per requestor object will be
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* sent.
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* <P>
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*
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* The listener will be unregistered when all services that were
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* obtained by that requestor for that service class are released.
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* <P>
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*
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* If the requested service class is not available, or if this
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* <code>BeanContextServices</code> object chooses not honor the
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* request because the service class has been revoked or for some
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* other reason, then this method will return <code>null</code>.
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* <P>
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*
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* This method may throw unchecked exceptions, so watch out.
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*
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* @specnote it is not specified what happens when two subsequent
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* calls are made to <code>getService()</code> with the
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* same requestor object and service class but different
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* listeners. Which listener is to be notified?
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*
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* @param requestorChild the <code>BeanContextChild</code>
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* associated with the requestor. Typically this will be
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* the same as the requestor itself, but since any
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* <code>Object</code>, even one outside the hierarchy, may
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* make a request, this parameter is necessary. Only weak
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* references to this will be retained, and it will never
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* be changed, only queried in a read-only manner.
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* @param requestor the actual requestor of the service. Only
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* weak references to this will be retained, and it will
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* never be changed, only queried in a read-only manner.
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* @param serviceClass the <code>Class</code> of the service being
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* requested.
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* @param serviceSelector a parameter to customize the service
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* returned with.
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* @param listener a listener that will be notified if the service
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* being requested is revoked.
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* @return an instance of <code>serviceClass</code> (such that
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* <code>instanceof</code> serviceClass is true), or
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* <code>null</code>.
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*/
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Object getService (BeanContextChild requestorChild, Object requestor,
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Class serviceClass, Object serviceSelector,
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BeanContextServiceRevokedListener listener)
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throws TooManyListenersException;
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/**
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* Get a list of all service classes supported.
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* <P>
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*
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* This method must synchronize on
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* <code>BeanContext.globalHierarchyLock</code>.
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*
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* @return a list of all service classes supported.
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* @see java.beans.beancontext.BeanContext#globalHierarchyLock
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*/
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Iterator getCurrentServiceClasses ();
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/**
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* Get a list of valid service selectors for the specified service class.
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* <P>
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*
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* If the specified service class does not have a finite number of
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* valid service selectors, it should return <code>null</code>.
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* If it takes a general <code>Integer</code> parameter, for
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* example, you may as well return <code>null</code> or the poor
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* soul who called this method will be iterating all day.
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* <P>
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*
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* If it has no valid service selectors, it should still return an empty
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* <code>Iterator</code>.
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*
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* @param serviceClass the service class to get selectors for.
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* @return a list of valid service selectors for the service
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* class, or <code>null</code>.
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*/
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Iterator getCurrentServiceSelectors (Class serviceClass);
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/**
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* Tell whether the specified service class is available.
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* Iff getService() could return a non-null value for the
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* specified service, this method will return <code>true</code>.
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*
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* @param serviceClass the service class to check on.
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* @return whether the specified service class is available.
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*/
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boolean hasService (Class serviceClass);
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/**
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* Add a listener on all adds and removes of services.
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* @param listener the listener to add.
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*/
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void addBeanContextServicesListener (BeanContextServicesListener listener);
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/**
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* Remove a listener on all adds and removes of services.
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* @specnote it is not certain whether this should remove this
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* listener if it was specified in
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* <code>getService()</code>.
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* @param listener the listener to add.
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*/
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void removeBeanContextServicesListener (BeanContextServicesListener listener);
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}
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