--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-5F641F7A-AEAA-5C3E-9179-C3707F10E6DC.dita	Wed Mar 31 11:11:55 2010 +0100
@@ -0,0 +1,83 @@
+<?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 task
+  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">
+<task id="GUID-5F641F7A-AEAA-5C3E-9179-C3707F10E6DC" xml:lang="en"><title>Starting
+and Finishing Transactions: Tutorial</title><shortdesc>This topic shows you how to start, finish and roll back a transaction
+with the Comms Database. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
+
+
+<prereq id="GUID-17B4987D-BD5C-5CD8-8E51-251431BD4E70"><p>Before you start,
+you must understand: </p> <ul>
+<li id="GUID-CE226134-308A-5B1C-BE3F-8AD1976CA1F0"><p>the general concept
+of the Comms Database </p> </li>
+<li id="GUID-5616BB6A-1FAE-56C3-B996-6AA7A1D41A75"><p>the specific concept
+of Comms Database Transactions </p> </li>
+<li id="GUID-F546E315-A6F2-5612-9DB2-66C6037E0FC3"><p>how to write and build
+application code to run on Symbian platform </p> </li>
+</ul> </prereq>
+<context id="GUID-47D01F8A-228E-5D1B-8764-13AC73E99950"><p>A transaction is
+a sequence of read and write operations. In a transaction all operations must
+be successful to make sure of the integrity of the data. </p> <p>A tool or
+application must mark the start of a transaction. The tool or application
+must also mark the end of a transaction. </p> <p>A transaction ends normally
+or the transaction is rolled back. A transaction is rolled back when one of
+the read or write operations fails. Other events can cause the tool or application
+to abandon the transaction. Other events depend on the purpose of the tool
+or application. </p> <p>Create a session with the Comms Database before you
+start a transaction. </p> <p>There are many ways to implement transactions.
+The procedure below is one method. The method shows the principle of transactions.
+The method you use depends on the organisation of your code. </p> </context>
+<steps id="GUID-012CB103-90DC-54F1-A4B4-512498EBC563">
+<step id="GUID-1E102596-F9BE-57BD-84A4-4C51BCD8A340"><cmd>Make sure that you
+have created a session before you start your first transaction. </cmd>
+</step>
+<step id="GUID-02951E12-339B-52D2-B42F-4977DC543090"><cmd>Start the transaction
+before you start the operations that access the database. Commit the transaction
+if all operations are successful. Rollback the transaction if any operation
+fails. </cmd>
+
+<info>The code uses the functions: <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBSession::OpenTransactionL()</apiname></xref>, <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBSession::CommitTransactionL()</apiname></xref> and <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBSession::RollbackTransactionL()</apiname></xref>. </info>
+<stepxmp><codeblock id="GUID-FAD16FB7-AC98-5579-AF89-848633BA7D10" xml:space="preserve">...
+
+// This code fragment assumes that a session with the Comms Database has been created.
+// iDb is a pointer to a CMDBSession object
+
+TInt rc;
+
+TRAP(rc,PerformSequenceOfOperationsL());
+if (!rc)
+    {
+    // Sequence of read and write operations has failed.
+    iDb-&gt;RollbackTransactionL();
+    ...
+    }
+...</codeblock> </stepxmp>
+<stepxmp><codeblock id="GUID-B7D81AF6-6D77-5CE9-A91A-E8093BA2802E" xml:space="preserve">...
+void PerformSequenceOfOperationsL()
+    {
+    // Start a transaction
+    iDb-&gt;OpenTransactionL();
+    ...
+    // Sequence of read and write operations
+    ...
+    // Commit the changes to the Comms Database. This assumes that
+    // all operations have completed successfully, and no other event has
+    // caused the sequence of operations to be abandoned.
+    iDb-&gt;CommitTransactionL()
+    ...
+    }
+...</codeblock> </stepxmp>
+</step>
+</steps>
+</taskbody><related-links>
+<link href="GUID-1AFDDD6F-CB99-587D-A0B5-D3F5B27F7135.dita"><linktext>Comms Database
+                concepts</linktext></link>
+</related-links></task>
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