ORBInitializerOperations (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Java™ Platform
Standard Ed. 6

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org.omg.PortableInterceptor
Interface ORBInitializerOperations

All Known Subinterfaces:: ORBInitializer

public interface ORBInitializerOperations

Facilitates interceptor registration and ORB initialization.

Interceptors are intended to be a means by which ORB services gain access to ORB processing, effectively becoming part of the ORB. Since Interceptors are part of the ORB, when ORB.init returns an ORB, the Interceptors shall have been registered. Interceptors cannot be registered on an ORB after it has been returned by a call to ORB.init.

An Interceptor is registered by registering an associated ORBInitializer object which implements the ORBInitializer interface. When an ORB is initializing, it shall call each registered ORBInitializer, passing it an ORBInitInfo object which is used to register its Interceptor.

Registering ORB Initializers in Java

ORBInitializers are registered via Java ORB properties.

The property names are of the form:

org.omg.PortableInterceptor.ORBInitializerClass.<Service>

where <Service> is the string name of a class which implements

org.omg.PortableInterceptor.ORBInitializer

To avoid name collisions, the reverse DNS name convention should be used. For example, if company X has three initializers, it could define the following properties:

org.omg.PortableInterceptor.ORBInitializerClass.com.x.Init1
org.omg.PortableInterceptor.ORBInitializerClass.com.x.Init2
org.omg.PortableInterceptor.ORBInitializerClass.com.x.Init3

During ORB.init, these ORB properties which begin with org.omg.PortableInterceptor.ORBInitializerClass shall be collected, the <Service> portion of each property shall be extracted, an object shall be instantiated with the <Service> string as its class name, and the pre_init and post_init methods shall be called on that object. If there are any exceptions, the ORB shall ignore them and proceed.

Example

A client-side logging service written by company X, for example, may have the following ORBInitializer implementation:

 package com.x.logging;
 
 import org.omg.PortableInterceptor.Interceptor; 
 import org.omg.PortableInterceptor.ORBInitializer; 
 import org.omg.PortableInterceptor.ORBInitInfo; 
 
 public class LoggingService implements ORBInitializer { 
     void pre_init( ORBInitInfo info ) { 
         // Instantiate the Logging Service s Interceptor. 
         Interceptor interceptor = new LoggingInterceptor(); 

         // Register the Logging Service s Interceptor. 
         info.add_client_request_interceptor( interceptor ); 
     } 
 
     void post_init( ORBInitInfo info ) { 
         // This service does not need two init points. 
     } 
 }

To run a program called MyApp using this logging service, the user could type:

java -Dorg.omg.PortableInterceptor.ORBInitializerClass.com.x.Logging.LoggingService MyApp

Notes about Registering Interceptors

Request Interceptors are registered on a per-ORB basis.

To achieve virtual per-object Interceptors, query the policies on the target from within the interception points to determine whether they should do any work.

To achieve virtual per-POA Interceptors, instantiate each POA with a different ORB. While Interceptors may be ordered administratively, there is no concept of order with respect to the registration of Interceptors. Request Interceptors are concerned with service contexts. Service contexts have no order, so there is no purpose for request Interceptors to have an order. IOR Interceptors are concerned with tagged components. Tagged components also have no order, so there is no purpose for IOR Interceptors to have an order.

Registration code should avoid using the ORB (i.e., calling ORB.init with the provided orb_id). Since registration occurs during ORB initialization, results of invocations on this ORB while it is in this state are undefined.

See Also:: ORBInitInfo

Method Summary

void post_init(ORBInitInfo info)
Called during ORB initialization.

void pre_init(ORBInitInfo info)
Called during ORB initialization.

Method Summary
`void`	`post_init(ORBInitInfo info)` Called during ORB initialization.
`void`	`pre_init(ORBInitInfo info)` Called during ORB initialization.

Method Detail

pre_init

void pre_init(ORBInitInfo info)

Called during ORB initialization. If it is expected that initial services registered by an interceptor will be used by other interceptors, then those initial services shall be registered at this point via calls to ORBInitInfo.register_initial_reference.

Parameters:: info - provides initialization attributes and operations by which Interceptors can be registered.

post_init

void post_init(ORBInitInfo info)

Called during ORB initialization. If a service must resolve initial references as part of its initialization, it can assume that all initial references will be available at this point.

Calling the post_init operations is not the final task of ORB initialization. The final task, following the post_init calls, is attaching the lists of registered interceptors to the ORB. Therefore, the ORB does not contain the interceptors during calls to post_init. If an ORB-mediated call is made from within post_init, no request interceptors will be invoked on that call. Likewise, if an operation is performed which causes an IOR to be created, no IOR interceptors will be invoked.

Parameters:: info - provides initialization attributes and operations by which Interceptors can be registered.