| author | avstepan |
| Sun, 13 Sep 2015 23:31:47 +0300 | |
| changeset 32688 | 936c391804a5 |
| parent 30826 | 725746fe9e37 |
| permissions | -rw-r--r-- |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> |
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<html> |
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<head> |
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<!-- |
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Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. |
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DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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This code is free software; you can redistribute it and/or modify it |
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under the terms of the GNU General Public License version 2 only, as |
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published by the Free Software Foundation. Oracle designates this |
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particular file as subject to the "Classpath" exception as provided |
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by Oracle in the LICENSE file that accompanied this code. |
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This code is distributed in the hope that it will be useful, but WITHOUT |
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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version 2 for more details (a copy is included in the LICENSE file that |
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accompanied this code). |
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You should have received a copy of the GNU General Public License version |
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2 along with this work; if not, write to the Free Software Foundation, |
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Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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or visit www.oracle.com if you need additional information or have any |
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questions. |
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--> |
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</head> |
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<body bgcolor="white"> |
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<P>Provides classes and interfaces that enable traversal of the data value |
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associated with an <code>any</code> at |
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runtime, and extraction of the primitive constituents of the data value. |
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<P>An <code>any</code> can be passed to a program that doesn't have any static information |
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for the type of the <code>any</code> (code generated for the type by an IDL compiler has not |
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been compiled with the object implementation). As a result, the object receiving the |
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<code>any</code> does not have a portable method of using it. |
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<P><code>DynAny</code>s enable traversal of the data value associated with an |
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<code>any</code> at runtime, and extraction of the primitive constituents of the data value. |
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This is especially helpful for writing powerful generic servers (bridges, event channels |
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supporting filtering). Similarly, this facility enables the construction of an |
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<code>any</code> at runtime, without having static knowledge of its type. This is especially |
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helpful for writing generic clients (bridges, browsers, debuggers, user interface tools). |
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<P><code>Any</code> values can be dynamically interpreted (traversed) and constructed through |
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<code>DynAny</code> objects. A <code>DynAny</code> object is associated with a data |
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value which corresponds to a copy of the value inserted into an <code>Any</code>. A |
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<code>DynAny</code> object may be viewed as an ordered collection of component |
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<code>DynAny</code>s. For <code>DynAny</code>s representing a basic type, such as <code>long</code>, |
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or a type without components, such as an empty exception, the ordered collection of |
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components is empty. |
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changeset
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<P>Each <code>DynAny</code> object maintains the notion of a current position into its collection |
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of component <code>DynAny</code>s. The current position is identified by an index value that runs |
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from 0 to n-1, where <em>n</em> is the number of components. The special index value -1 |
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indicates a current position that points nowhere. |
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For values that cannot have a current position (such as an empty exception), |
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the index value is fixed at -1. |
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If a <code>DynAny</code> is initialized with a value that has components, the index is |
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initialized to 0. |
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After creation of an uninitialized <code>DynAny</code> (that is, a <code>DynAny</code> that |
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has no value but a <code>TypeCode</code> |
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that permits components), the current position depends on the type of value represented by |
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the <code>DynAny</code>. (The current position is set to 0 or -1, depending on whether the |
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new <code>DynAny</code> |
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gets default values for its components.) |
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<P>The iteration operations <code>rewind</code>, <code>seek</code>, and <code>next</code> |
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can be used to change the current position |
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and the <code>current_component</code> operation returns the component at the current |
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position. |
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The <code>component_count</code> operation returns the number of components of a |
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<code>DynAny</code>. |
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Collectively, these operations enable iteration over the components of a |
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<code>DynAny</code>, for example, |
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to (recursively) examine its contents. |
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<P>A constructed <code>DynAny</code> object is a <code>DynAny</code> object associated with |
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a constructed type. |
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There is a different interface, inheriting from the <code>DynAny</code> interface, |
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associated with |
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each kind of constructed type in IDL (fixed, enum, struct, sequence, union, array, |
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exception, and value type). A constructed <code>DynAny</code> object exports operations |
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that enable the creation of new <code>DynAny</code> objects, |
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each of them associated with a component of the constructed data value. |
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As an example, a <code>DynStruct</code> is associated with a <code>struct</code> value. This |
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means that the <code>DynStruct</code> |
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may be seen as owning an ordered collection of components, one for each structure member. |
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The <code>DynStruct</code> object exports operations that enable the creation of new |
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<code>DynAny</code> objects, |
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each of them associated with a member of the <code>struct</code>. |
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<P>If a <code>DynAny</code> object has been obtained from another (constructed) |
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<code>DynAny</code> object, |
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such as a <code>DynAny</code> representing a structure member that was created from a |
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<code>DynStruct</code>, |
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the member <code>DynAny</code> is logically contained in the <code>DynStruct</code>. |
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Calling an <code>insert</code> or <code>get</code> operation leaves the current position |
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unchanged. |
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Destroying a top-level <code>DynAny</code> object (one that was not obtained as a component |
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of another <code>DynAny</code>) |
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also destroys any component <code>DynAny</code> objects obtained from it. |
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Destroying a non-top level <code>DynAny</code> object does nothing. |
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Invoking operations on a destroyed top-level <code>DynAny</code> or any of its descendants |
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raises OBJECT_NOT_EXIST. |
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If the programmer wants to destroy a <code>DynAny</code> object but still wants to |
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manipulate some component |
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of the data value associated with it, then he or she should first create a |
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<code>DynAny</code> for the component |
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and, after that, make a copy of the created <code>DynAny</code> object. |
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<P>The behavior of <code>DynAny</code> objects has been defined in order to enable efficient |
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implementations |
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in terms of allocated memory space and speed of access. <code>DynAny</code> objects are |
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intended to be used |
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for traversing values extracted from <code>any</code>s or constructing values of |
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<code>any</code>s at runtime. |
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Their use for other purposes is not recommended. |
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<H2>Handling DynAny objects</H2> |
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<P><code>Insert</code> and <code>get</code> operations are necessary to handle basic |
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<code>DynAny</code> objects |
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but are also helpful to handle constructed <code>DynAny</code> objects. |
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Inserting a basic data type value into a constructed <code>DynAny</code> object |
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implies initializing the current component of the constructed data value |
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associated with the <code>DynAny</code> object. For example, invoking |
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<code>insert_boolean</code> on a |
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<code>DynStruct</code> implies inserting a <code>boolean</code> data value at the current |
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position |
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of the associated <code>struct</code> data value. |
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A type is consistent for inserting or extracting a value if its <code>TypeCode</code> is |
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equivalent to |
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the <code>TypeCode</code> contained in the <code>DynAny</code> or, if the |
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<code>DynAny</code> has components, is equivalent to the <code>TypeCode</code> |
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of the <code>DynAny</code> at the current position. |
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<P>Basic operations include: |
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<UL> |
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<LI>insert_boolean, get_boolean |
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<LI>insert_char, get_char |
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<LI>insert_short, get_short |
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<LI>insert_ushort, get_ushort |
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<LI>insert_long, get_long |
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<LI>insert_ulong, get_ulong |
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<LI>insert_double, get_double |
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<LI>insert_string, get_string |
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<LI>insert_reference, get_reference |
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<LI>insert_typecode, get_typecode |
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<LI>insert_longlong, get_longlong |
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<LI>insert_ulonglong, get_ulonglong |
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<LI>insert_longdouble, get_longdouble |
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<LI>insert_wchar, get_wchar |
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<LI>insert_wstring, get_wstring |
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<LI>insert_any, get_any |
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<LI>insert_dyn_any, get_dyn_any |
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<LI>insert_val, get_val |
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<LI>insert_octet, get_octet |
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<LI>insert_float, get_float |
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<LI>get_value |
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<LI>get_as_string |
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<LI>get_as_ulong |
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<LI>get_members |
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<LI>get_members_as_dyn_any |
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<LI>get_discriminator |
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<LI>get_length |
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<LI>get_elements |
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<LI>get_elements_as_dyn_any |
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<LI>get_boxed_value |
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<LI>get_boxed_value_as_dyn_any |
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</UL> |
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<P><code>DynAny</code> and <code>DynAnyFactory</code> objects are intended to be local to |
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the process in which they are |
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created and used. This means that references to <code>DynAny</code> and |
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<code>DynAnyFactory</code> objects cannot be exported |
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to other processes, or externalized with <code>ORB.object_to_string()</code>. |
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If any attempt is made to do so, the offending operation will raise a MARSHAL system |
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exception. |
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Since their interfaces are specified in IDL, <code>DynAny</code> objects export operations |
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defined in the standard |
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<code>org.omg.CORBA.Object</code> interface. However, any attempt to invoke operations |
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exported through the <code>Object</code> |
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interface may raise the standard NO_IMPLEMENT exception. |
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An attempt to use a <code>DynAny</code> object with the DII may raise the NO_IMPLEMENT |
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exception. |
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<H3>Package Specification</H3> |
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<P>For a precise list of supported sections of official specifications with which |
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the Java[tm] Platform, Standard Edition 6 ORB complies, see <A |
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HREF="../CORBA/doc-files/compliance.html">Official Specifications for CORBA |
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support in Java[tm] SE 6</A>. |
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@since 1.4 |
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<br> |
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@serial exclude |
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</body> |
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</html> |