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+++ b/Symbian3/SDK/Source/GUID-80F2A7AC-6E86-54F2-96F0-4417A2AEA017.dita	Thu Jan 21 18:18:20 2010 +0000
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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-80F2A7AC-6E86-54F2-96F0-4417A2AEA017" xml:lang="en"><title>Handle-numbers</title><shortdesc>This document describes the use of handle-numbers to identify handles.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>A handle is a way in which a thread or process can identify an object that
+is owned or managed by another thread or process. Such objects are Kernel
+side objects.</p>
+<p>A handle uses a number, the handle-number, to identify the associated Kernel
+side object. The handle, an instance of a <codeph>RHandleBase</codeph> derived
+class, encapsulates the handle-number.</p>
+<p>The objects referred to by handles are always instances of <codeph>CObject</codeph> derived
+classes, i.e. they are reference counting objects. The handle-number is created
+when the object is created (or opened, if the object already exists) and added
+to an object index.</p>
+<p>Typically, calling <codeph>Open()</codeph> or <codeph>Create()</codeph> or
+a similarly named function on an <codeph>RHandleBase</codeph>  <i>derived</i> class
+causes the associated object to be created or opened and added to an object
+index, owned either by the thread or the process. Adding the object to the
+object index creates a handle-number and this is returned to, and encapsulated
+by, the handle.</p>
+<p>For example, <codeph>RMutex</codeph> is the handle for a mutex; all user
+side interaction with a specific mutex is directed through an instance of <codeph>RMutex</codeph>.
+The <codeph>RMutex</codeph> object exists on the user side; the corresponding
+mutex (a DMutex object) exists on the Kernel side.</p>
+<fig id="GUID-86253ED0-C374-52C5-BF3E-463D09A3ECD3">
+<image href="GUID-8E907968-E6F8-5792-9B04-664971762FFF_d0e205603_href.png" placement="inline"/>
+</fig>
+<p>Here, code running on the user side constructs an <codeph>RMutex</codeph> and
+calls its <codeph>Create()</codeph> member function. This causes the Kernel
+to:</p>
+<ul>
+<li id="GUID-69E652C5-BC3E-5C2C-95DE-8F0BC5DF6C13"><p>construct the corresponding
+Kernel object, a <codeph>DMutex</codeph> </p> </li>
+<li id="GUID-CA86B942-A4CA-5E9E-BA36-2E581C01C646"><p>add the <codeph>DMutex</codeph> to
+the current thread's object index (a <codeph>CObjectIx</codeph>)</p> </li>
+<li id="GUID-6BD33635-074D-59CB-BB7E-1AF6F0290481"><p>return the handle-number
+to the RMutex.</p> </li>
+</ul>
+<codeblock id="GUID-96432516-6FC7-584C-843D-17D0E07956CB" xml:space="preserve">...
+RMutex m;
+m.Create();
+...</codeblock>
+<p>See also:</p>
+<ul>
+<li id="GUID-B218DFCC-054D-53ED-9C36-9947C1BC2895"><p><xref href="GUID-A95CDFDE-285F-5DE2-AADE-29B2B9663757.dita">The
+object index</xref> </p> <p><xref href="GUID-8C4EB8E0-78F0-553D-91AE-EC070A47B0EE.dita">The
+handle-number and the object index</xref> </p> <p><xref href="GUID-A52E8853-9A8A-5B66-A2B0-F943B32AA5C6.dita">Reference
+counting objects</xref> </p> </li>
+</ul>
+</conbody></concept>
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