Interceptor


1   package org.apache.beehive.controls.spi.svc;
2   /*
3    * Copyright 2004 The Apache Software Foundation.
4    *
5    * Licensed under the Apache License, Version 2.0 (the "License");
6    * you may not use this file except in compliance with the License.
7    * You may obtain a copy of the License at
8    * 
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   *
17   * $Header:$
18   */
19  
20  import org.apache.beehive.controls.api.bean.ControlBean;
21  
22  import java.lang.reflect.Method  ;
23  
24  /**
25   * The controls implementation architecture has a interceptor model for
26   * adding annotation-based features.  This model provides the ability to
27   * associate a JavaBeans service interface with an annotation to define
28   * its runtime feature behaviour.  Such interfaces must extend this
29   * Interceptor interface, which defines the contract that the controls runtime
30   * has with interceptors.
31   *
32   * The controls runtime will automatically instantiate and execute
33   * implementations of interceptors at the appropriate execution points
34   * (pre/post invocation of a control operation, etc).
35   *
36   * A return value of "true" from each Interceptor method indicates to the runtime
37   * that it should continue execution through the normal flow of control (ie, subsequent
38   * interceptors and operation/event execution).  "false" indicates that the interceptor
39   * has fully processed the operation and the runtime should "pivot" out.  
40   */
41  public interface Interceptor
42  {
43      /** Called before a control operation is invoked */
44      public void preInvoke( ControlBean cb, Method   m, Object   [] args)
45          throws InterceptorPivotException;
46      /** Called after a control operation is invoked */
47      public void postInvoke( ControlBean cb, Method   m, Object   [] args, Object   retval, Throwable   t );
48  
49      /** Called before a control event is fired (through a client proxy) */
50      public void preEvent( ControlBean cb, Class   eventSet, Method   m, Object   [] args )
51          throws InterceptorPivotException;
52      /** Called after a control event is fired (through a client proxy) */
53      public void postEvent( ControlBean cb, Class   eventSet, Method   m, Object   [] args);
54  }
55
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