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+++ b/Symbian3/SDK/Source/GUID-D14CD452-BFCE-5EBA-B73B-61AA045D23E4.dita Wed Mar 31 11:11:55 2010 +0100
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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-D14CD452-BFCE-5EBA-B73B-61AA045D23E4" xml:lang="en"><title>Log
+Engine Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>This topic describes the key concepts of Log Engine. </p>
+<section id="GUID-ECD7C71D-F465-48FC-8478-65E5D09E6124"><title>Purpose</title> <p>Used to record events of interest to the
+user, of which they may not be immediately aware, or of high importance as
+costs are incurred, such as telephone calls. These events can be retrieved
+by a viewer application and displayed to the user. </p> </section>
+<section id="GUID-44BF0863-2E2B-4E2B-A04A-03956C9A64BA"><title>Architectural relationships</title> <p>The Log Engine is split
+into a wrapper (a stub interface) that is present on all UI variants, and
+an actual logging DLL that may or may not be present. On UI variants on which
+the actual logging engine is not present, calls to the wrapper will have no
+effect. Programs written for multiple UI variants should use the wrapper only.
+Programs for a particular UI variant on which the log engine is present can
+use it directly. </p> </section>
+<section id="GUID-D2D4E2AA-1842-4394-B916-3B473C578DBE"><title>Description</title> <p>The API has five key concepts: log
+engine wrapper, log client, event, view, and filter. </p> <p><b>Log
+engine wrapper</b> </p> <p>The log engine wrapper provides simple interfaces
+to record events, and is present on all UI variants. The wrapper interfaces
+are <xref href="GUID-146D719E-BDD6-3F20-80B1-EDE09081A6EA.dita"><apiname>CLogWrapper</apiname></xref> and <xref href="GUID-4A7D312F-A8C6-3663-8455-13FA73F1CFB5.dita"><apiname>CLogBase</apiname></xref>. </p> <p><b>Log client</b> </p> <p>The log client is the main direct interface on
+the log engine. It is used to add, delete, and change log events, and allows
+log administration. It is also used to create filtered views of events. </p> <p>The
+log client interface is <xref href="GUID-51C67545-12BA-326D-BD8F-662B24C68ED2.dita"><apiname>CLogClient</apiname></xref>. </p> <p><b>Event</b> </p> <p>A log event is an entry in the log. Events have a fixed
+number of data fields, though some fields do not apply to all events. </p> <p>The
+event interface is <xref href="GUID-CDFB61A7-1C74-3F63-9FDF-5A3B8603A010.dita"><apiname>CLogEvent</apiname></xref>. </p> <p><b>View</b> </p> <p>A view allows a filtered list of events to be accessed.
+Views are provided for the main event log (<codeph>CLogViewEvent</codeph>)
+and for recent events only (<xref href="GUID-F40F9556-F223-36A5-9812-6EF6FF3F5156.dita"><apiname>CLogViewRecent</apiname></xref>). </p> <p><b>Filter </b> </p> <p>A filter specifies the type of events that appear
+in a view. The filter interface is <xref href="GUID-99144BA6-F79A-3D3C-B1D3-272B3723C42C.dita"><apiname>CLogFilter</apiname></xref>. </p> </section>
+</conbody><related-links>
+<link href="GUID-B0D76734-1DB7-5465-91AE-BB3521599A75.dita"><linktext>How To Use
+the Log Engine</linktext></link>
+<link href="GUID-F3770B99-5228-5D29-8CA6-71028A327714.dita"><linktext> Log Engine
+Using Central Repository</linktext></link>
+</related-links></concept>
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