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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-F0BDE1EC-5042-5328-9290-22BB2189F6B4" xml:lang="en"><title>How
+to Implement a LBS Set Clock Plug-in DLL</title><shortdesc>This topic describes how to implement a LBS set clock plug-in class. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<section><title>Required background</title> <p><xref href="GUID-A5510456-A5EB-59EC-B146-74D58A118875.dita">LBS
+system clock adjustment overview</xref> describes the set clock plug-in interface. </p> </section>
+<section><title>Introduction </title> <p>LBS contains a default implementation
+of a set clock module that sets the system clock time by calling <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-145F52E6-2A29-3FF1-8AD1-7009BE0074D7"><apiname>User::SetUTCTime()</apiname></xref>. </p> <p>To
+set the system clock by some other method, a licensee must create a set clock
+plug-in DLL and configure LBS to use it. </p> </section>
+<section><title>Implementing the plug-in class</title> <p>Licensee set clock
+plug-in classes must derive from the abstract base class <codeph>CGPSSetClockBase</codeph> shown
+in figure 1. </p> <p> <codeph>CGPSSetClockBase</codeph> is packaged in <filepath>GPSSetClock.dll</filepath>.
+An implementation includes <filepath>GPSSetClockBase.h</filepath> and links
+with <filepath>GPSSetClock.lib</filepath>. </p> <fig id="GUID-CAE2F49D-6B7A-5F6F-A0BD-25A8475CDE32">
+<title>              Figure 1. CGPSSetClockBase is the base class for LBS
+set clock              plug-in classes.            </title>
+<image href="GUID-9BA295BC-627C-5B82-B669-F4F7B55E3F82_d0e437287_href.png" placement="inline"/>
+</fig> <p>To implement a set clock plug-in a developer must follow the steps
+in the next section. </p> </section>
+<section><title>Procedure</title> <ol id="GUID-657B1DA8-2A2B-583B-AADD-3E94AEE04751">
+<li id="GUID-D2515C64-C814-53BB-B161-DB571F4FE42B"><p>Create a class derived
+from <codeph>CGPSSetClockBase</codeph>: </p> <codeblock id="GUID-E4FE605C-689D-5A68-9FA4-E394DB366C5B" xml:space="preserve">#include &lt;GPSSetClockBase.h&gt;
+
+class CGPSSetClockImpl : public CGPSSetClockBase
+{
+    
+    public:
+  static CGPSSetClockImpl* NewL();
+     
+  virtual TInt SetUTCTime(const TTime&amp; aTime);
+  virtual ~CGPSSetClockImpl();
+  
+ private:
+  CGPSSetClockImpl();
+  void ConstructL();
+     
+};
+</codeblock> <p> <i>Note that the implementation class must only allocate
+memory on construction</i>, not when <xref href="GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5.dita#GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5/GUID-F6922F15-F4D3-31D9-86AD-B2809AA111A1"><apiname>CGPSSetClockBase::SetUTCTime()</apiname></xref> is
+called. This is because LBS must always be able to respond to emergency services
+location requests and so must never run out of memory at runtime. Memory for
+the set clock plug-in DLL must therefore be allocated on startup of the LBS
+subsystem when the ECom framework loads the plug-in DLL and calls the <codeph>NewL()</codeph> function
+on the implementation class. </p> <codeblock id="GUID-4A865931-1C48-5396-BD5B-BF590CE031E9" xml:space="preserve">CGPSSetClockImpl* CGPSSetClockImpl::NewL()
+{
+    // Allocate all required memory here or in ConstructL()
+ ...
+}
+</codeblock> </li>
+<li id="GUID-AF16291B-786D-5E90-917C-ABE8F38D664D"><p>Implement the virtual
+method <xref href="GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5.dita#GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5/GUID-F6922F15-F4D3-31D9-86AD-B2809AA111A1"><apiname>CGPSSetClockBase::SetUTCTime()</apiname></xref>. The implementation
+of this method is licensee specific and depends on the method that the licensee
+uses to set the system clock. </p> <codeblock id="GUID-F5B3CC27-D8C1-5302-8AFE-CF92A2FEFD82" xml:space="preserve">
+TInt CGPSSetClockImpl::SetUTCTime(const TTime&amp; aTime)
+{
+    // Licensee method of setting the system clock
+ // Do not allocate any additional memory!
+    ...
+}
+</codeblock> </li>
+<li id="GUID-25E5345F-9B40-55B2-9FE4-4EBF5549DB59"><p>Package the class as
+an ECom plug-in DLL. </p> <p>See <xref href="GUID-7B304B12-D597-550C-9EAA-AB8B2A6A8531.dita">How
+to create implementation collections</xref> for information on how to package
+an implementation class as an ECom plug-in DLL. </p> <p> <b>Note:</b> LBS
+must be configured to use the licensee set clock plug-in DLL to set the system
+clock. <xref href="GUID-23BBC1D8-B3A0-5148-A4F1-22ECF3043E4E.dita">LBS administration</xref> describes
+how to configure LBS system clock synchronisation settings using either the
+LBS Administration API or a repository initialisation file. </p> </li>
+</ol> </section>
+</conbody><related-links>
+<link href="GUID-A5510456-A5EB-59EC-B146-74D58A118875.dita"><linktext>LBS System
+Clock Synchronisation Overview</linktext></link>
+</related-links></concept>
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