--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-CCCEC352-3A49-534C-9551-A4CAE1A3475E.dita	Thu Jan 21 18:18:20 2010 +0000
@@ -0,0 +1,57 @@
+<?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-CCCEC352-3A49-534C-9551-A4CAE1A3475E" xml:lang="en"><title>How
+to handle a single asynchronous request</title><shortdesc>This document describes how to handle a single asynchronous request.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>A thread that requests an asynchronous service from another thread can
+continue processing but eventually reaches a point where it must wait until
+the asynchronous request is complete before it can resume processing.</p>
+<p>Typically, the requester performs the following sequence:</p>
+<ul>
+<li id="GUID-0A1C409D-80A4-5EC0-AC59-A3D6C7E5228D"><p>creates an object of
+type <codeph>TRequestStatus</codeph> to monitor the state of the request.</p> </li>
+<li id="GUID-BBCD758B-2B52-5D83-9C13-FC0204600563"><p>calls the asynchronous
+provider's request function, passing the <codeph>TRequestStatus</codeph> object;
+all asynchronous functions are prototyped to take a <codeph>TRequestStatus</codeph> parameter.</p> </li>
+<li id="GUID-E874E08B-19EF-5887-A7CC-DED65B5A84B4"><p>uses the operating system
+function <codeph>User::WaitForRequest()</codeph> to allow the thread to wait
+for completion of the request.</p> </li>
+</ul>
+<codeblock id="GUID-6425F8F3-7196-56C7-9886-F599EEA9E07D" xml:space="preserve">TRequestStatus status;                        // Request status object
+someProvider.IssueRequest(parameters,status); // Issue the request
+...
+User::WaitForRequest(status);                 // Wait for completion
+if (status==KErrNone)
+    {
+    /* success */
+    }
+else if (status==KErrXxx)
+    {
+    /* check for some error */
+    }
+else // check for other error conditions etc.
+...</codeblock>
+<section id="GUID-E8B90FAF-1891-49EE-8915-D9265F8884AB"><title>Notes</title> <ul>
+<li id="GUID-99618D33-6281-5C32-B54B-4451F6228C85"><p>there is no special
+name for a request function; the request performed depends on the class, the
+function name and the parameters passed.</p> </li>
+<li id="GUID-F1D8C498-3A72-5C02-892B-8DB1792D651F"><p>when the request is
+complete, an integer is stored in the request status object to convey additional
+information about the completion of the function. The meaning of the completion
+code varies from function to function. Additionally, information returned
+by the request may be returned to reference parameters passed to the request
+function.</p> </li>
+<li id="GUID-E87D9AED-C897-5F19-8E34-A43C2E7AFF35"><p>The integer completion
+code must not be <codeph>KErrPending</codeph>. By convention, <codeph>KErrNone</codeph> indicates
+no error and <codeph>KErrCancel</codeph> indicates a cancelled request. Other
+values may be used for specific types of error.</p> </li>
+</ul> </section>
+</conbody></concept>
\ No newline at end of file