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+++ b/Symbian3/SDK/Source/GUID-579D7C32-B6C8-5C77-88A5-B3078729E1BA.dita	Thu Jan 21 18:18:20 2010 +0000
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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-579D7C32-B6C8-5C77-88A5-B3078729E1BA" xml:lang="en"><title>How
+to implement a simple client interface</title><shortdesc>Provides code snippets to help you to implement a simple client
+interface.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<section id="GUID-EE1BFD0F-EE55-47BA-A8FD-D753EC132255"><title>Client side session with a server</title> <p>A client side
+session is represented by an instance of a class derived from <codeph>RSessionBase</codeph> which
+provides the behaviour for connecting to the server and sending messages to
+it. </p> <p>In the following code fragment, taken from the example that can
+be found at <filepath>...\examples\Base\IPC\ClientServer\simple</filepath>,
+the class <codeph>RCountServSession</codeph>, derived from <codeph>RSessionBase</codeph>,
+represents the client side session with a server. In the example, this may
+be referred to as the "count server". Note that sessions can not be shared
+in this example, and it just shows the basic mechanics of the client/server
+interaction. </p> <codeblock id="GUID-48AC1BF2-BA67-5959-A49A-AF57AC25E155" xml:space="preserve">class RCountServSession : public RSessionBase
+    {
+public:
+    RCountServSession();
+    TInt Connect();
+    TVersion Version() const;
+    TInt UnsupportedRequest();
+    TInt SetFromString(const TDesC&amp; aString);
+    void Increase();
+    void Decrease();
+    void IncreaseBy(TInt anInt);
+    void DecreaseBy(TInt anInt);
+    void Reset();
+    TInt CounterValue();
+    void BadRequest();
+    void Close();
+private:
+    RThread iServerThread;
+    };</codeblock> <p>The important points are: </p> <ul>
+<li id="GUID-B6AC51AC-91A3-5794-815A-292E308735F6"><p>Use <codeph>Connect()</codeph> to
+start the count server. This calls <codeph>RSessionBase::CreateSession()</codeph> to
+create a session with the server. Note that in this simple example, the server
+is implemented as a separate thread, which is started by the example executable. </p> </li>
+<li id="GUID-EBDC7F23-8D2F-5093-8C32-50C3DE137EF5"><p>Use a client interface
+function, such as <codeph>Increase()</codeph>, to send a specific message
+to the server. The client interface function builds the message using the
+appropriate operation code and assembling a suitable <xref href="GUID-4AD02F14-1142-372F-9D11-224595932034.dita"><apiname>TIpcArgs</apiname></xref> object,
+i.e. the object containing the integers and/or the descriptor pointers to
+the message arguments in the client address space. </p> </li>
+</ul> <p>As an example, the function <codeph>SetFromString()</codeph> is implemented
+as follows: </p> <codeblock id="GUID-A673A2A4-0999-5EDE-9FFB-E0C7335B58D9" xml:space="preserve">TInt RCountServSession::SetFromString(const TDesC&amp; aString)
+    {
+    TIpcArgs args(&amp;aString);
+    return SendReceive(ECountServSetFromString, args);
+    }</codeblock> <p> <codeph>SendReceive()</codeph> is called, specifying
+an operation code <codeph>ECountServSetFromString</codeph> and a <xref href="GUID-4AD02F14-1142-372F-9D11-224595932034.dita"><apiname>TIpcArgs</apiname></xref> object
+containing argument values. In this case, there is only one argument - a pointer
+to a <codeph>TDesC</codeph> object containing the string to be passed to the
+server. Typically, operation codes are enum values defined in a header file
+visible to both the client interface and the server. Note that the client
+descriptor must remain in existence until the server request completes. </p> </section>
+</conbody></concept>
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