IORHelper (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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Java^TM 2 Platform
Std. Ed. v1.4.1

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org.omg.IOP
Class IORHelper

java.lang.Object
  |
  +--org.omg.IOP.IORHelper

public abstract class IORHelper
extends Object

Captures information about a object references, such as whether the object is null, what type it is, what protocols are supported, and what ORB services are available.

This data structure need not be used internally to any given ORB, and is not intended to be visible to application-level ORB programmers. It should be used only when crossing object reference domain boundaries, within bridges.

This data structure is designed to be efficient in typical single-protocol configurations, while not penalizing multiprotocol ones.

Object references have at least one tagged profile. Each profile supports one or more protocols and encapsulates all the basic information the protocols it supports need to identify an object. Any single profile holds enough information to drive a complete invocation using any of the protocols it supports; the content and structure of those profile entries are wholly specified by these protocols. A bridge between two domains may need to know the detailed content of the profile for those domains' profiles, depending on the technique it uses to bridge the domains.

Each profile has a unique numeric tag, assigned by the OMG. Profile tags in the range 0x80000000 through 0xffffffff are reserved for future use, and are not currently available for assignment.

Null object references are indicated by an empty set of profiles, and by a "Null" type ID (a string which contains only a single terminating character). A Null TypeID is the only mechanism that can be used to represent the type CORBA.Object. Type IDs may only be "Null" in any message, requiring the client to use existing knowledge or to consult the object, to determine interface types supported. The type ID is a Repository ID identifying the interface type, and is provided to allow ORBs to preserve strong typing. This identifier is agreed on within the bridge and, for reasons outside the scope of the interoperability specification, needs to have a much broader scope to address various problems in system evolution and maintenance. Type IDs support detection of type equivalence, and in conjunction with an Interface Repository, allow processes to reason about the relationship of the type of the object referred to and any other type.

The type ID, if provided by the server, indicates the most derived type that the server wishes to publish, at the time the reference is generated. The object's actual most derived type may later change to a more derived type. Therefore, the type ID in the IOR can only be interpreted by the client as a hint that the object supports at least the indicated interface. The client can succeed in narrowing the reference to the indicated interface, or to one of its base interfaces, based solely on the type ID in the IOR, but must not fail to narrow the reference without consulting the object via the "_is_a" or "_get_interface" pseudo-operations.

Constructor Summary

IORHelper()


Method Summary

static IOR extract(Any a)


static String id()


static void insert(Any a, IOR that)


static IOR read(InputStream istream)


static TypeCode type()


static void write(OutputStream ostream, IOR value)


Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IORHelper

public IORHelper()

Method Detail

insert

public static void insert(Any a,
                          IOR that)

extract

public static IOR extract(Any a)

type

public static TypeCode type()

id

public static String id()

read

public static IOR read(InputStream istream)

write

public static void write(OutputStream ostream,
                         IOR value)