<?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-3829BD20-3DCB-5489-8FC4-07F954E391BF" xml:lang="en"><title>Local

and global handles</title><shortdesc>This document explains the distinction between local and global

handles.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This is the issue of Kernel side object visibility.</p>

<p>Handles are said to be local or global.</p>

<p>A handle is <i>local</i>, if the Kernel object which that handle represents

is only visible to the thread that created it; no other thread can open a

handle to the same Kernel object.</p>

<p>Typically, code constructs the appropriate <codeph>RHandleBase</codeph> derived

object, e.g. an <codeph>RMutex</codeph>, and calls its <codeph>Create()</codeph>, <codeph>CreateLocal()</codeph> or

equivalent function to create the corresponding Kernel object.</p>

<p>A handle is <i>global</i>, if the Kernel object which that handle represents

is visible to all threads across all processes; any thread in any process

can open a handle to that same Kernel object. Typically, such a Kernel object

is intended for sharing.</p>

<p>For a global handle. the corresponding Kernel object is assigned a name.

The name gives that Kernel object an identity and is the key property which

allows other threads to open a handle onto that same object. It is usual to

use a <codeph>TFindHandleBase</codeph>  <i>derived</i> class to locate a global

Kernel object. The following diagram shows the general idea.</p>

<fig id="GUID-01C60CFA-8CA7-51CC-904E-158EC02959DE">

<image href="GUID-5398C2DC-9AFA-5517-BCBF-5964970B9656_d0e230704_href.png" placement="inline"/>

</fig>

<p>See also:</p>

<ul>

<li id="GUID-56D39619-C90C-51DF-9475-3B75FB189258"><p><xref href="GUID-FC639517-F138-5E84-B57A-6347F5A47B88.dita">Names

and fullnames</xref> in reference counting objects.</p> </li>

</ul>