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Symbian3/SDK/Source/GUID-4AEBF49C-E62A-5D0D-8181-600BF29DFFC7.dita
changeset 0 89d6a7a84779 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-4AEBF49C-E62A-5D0D-8181-600BF29DFFC7.dita	Thu Jan 21 18:18:20 2010 +0000
@@ -0,0 +1,69 @@
+<?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-4AEBF49C-E62A-5D0D-8181-600BF29DFFC7" xml:lang="en"><title>IPC:
+IPC Mechanisms</title><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>This example demonstrates how a parent process communicates with its child
+process using various IPC mechanisms. Two executables, a parent and a child
+(spawned by the parent) are created to demonstrate these mechanisms. The child
+process is created by the parent using the <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref> function.
+The parent process communicates with the child process using the following
+IPC mechanisms: </p>
+<ul>
+<li id="GUID-D1CABBD1-AC3A-5216-B2A6-D860C876DEDE"><p>Named pipes (FIFO -
+First in First Out) </p> </li>
+<li id="GUID-8FE87BCB-200D-5498-8F1A-851B861F8673"><p>Single pipe (<xref href="GUID-A9DB6E7C-B8D6-377A-BBE6-39E0A7A09E5D.dita"><apiname>popen()</apiname></xref> system
+call) </p> </li>
+</ul>
+<section><title>Download</title><p>Click on the following link to download
+the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-c5b6ac05-a3fb-45df-ab11-bd8ccc13537f.zip" scope="external">IPC.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-c5b6ac05-a3fb-45df-ab11-bd8ccc13537f.html" scope="peer">browse</xref> to view the example code. </p> </section>
+<section><title>Description</title> <p><b> Spawning the child process</b> </p> <p>The <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref> function
+creates the child process. A pointer to the process ID (<codeph>pid</codeph>)
+of the child process and the path of the child process are passed as arguments
+to this function. The parent waits for the child to terminate by calling the <xref href="GUID-8F5C89A4-7813-32C7-973E-F7F0F3690BC6.dita"><apiname>waitpid()</apiname></xref> function. </p> <p><b> Creating
+a named pipe</b> </p> <p>This example creates a named pipe using the <xref href="GUID-F4749DAA-1B29-3D1D-A3AA-0D52B851E501.dita"><apiname>mkfifo()</apiname></xref> function.
+The child writes data into the FIFO and then exits. The parent reads data
+from FIFO and writes it to the console. The first argument of the <xref href="GUID-F4749DAA-1B29-3D1D-A3AA-0D52B851E501.dita"><apiname>mkfifo()</apiname></xref> function
+indicates the path of the FIFO file. </p> <p><b> Opening a single pipe</b> </p> <p>The
+parent creates a child process and a pipe to the child process using the <xref href="GUID-A9DB6E7C-B8D6-377A-BBE6-39E0A7A09E5D.dita"><apiname>popen()</apiname></xref> function.
+A file handle to the pipe is returned to the parent and the parent uses this
+handle to read the data written to the pipe by the child. The path of the
+child process is passed as the first argument to the <xref href="GUID-A9DB6E7C-B8D6-377A-BBE6-39E0A7A09E5D.dita"><apiname>popen()</apiname></xref> function. </p> </section>
+<section><title>Build</title> <p>The following statements are present in all
+the <filepath>.mmp</filepath> files of the example: </p> <codeblock id="GUID-09782F92-8B25-5CF5-8027-599685F5726D" xml:space="preserve">SYSTEMINCLUDE epoc32\include\stdapis
+LIBRARY libc.lib
+STATICLIBRARY libcrt0.lib</codeblock> <p> <b>Note:</b> You require these statements
+because of the following reasons: </p> <ul>
+<li id="GUID-C735ED4D-4FDD-5535-ACA2-C645C3F10762"><p>The <filepath>epoc32\include\stdapis</filepath> directory
+contains header files such as, <filepath>stdio.h</filepath>, <filepath>unistd.h</filepath> and
+so on that are required to build an Open Environment application. </p> </li>
+<li id="GUID-6351CD50-ED02-5DC9-BAAF-971CB92EEAD3"><p>The <filepath>libc.lib</filepath> file
+contains the definitions of all functions that are defined in the header files
+associated with this example. </p> </li>
+<li id="GUID-C7A1D9C5-07E6-5FD1-B770-24180F04623A"><p>The <filepath>libcrt0.lib</filepath> file
+provides the <codeph>E32Main()</codeph> function, which is the entry point
+for the <codeph>main()</codeph> function of the example. </p> </li>
+</ul> <p> <xref href="GUID-3100800B-B2F7-50EF-BD4C-3C345ECCB2A5.dita">The Symbian
+OS build process</xref> describes how to build this example. The <codeph>IPC</codeph> builds
+the following binaries in the standard location (<filepath>\epoc32\release\winscw\&lt;build_variant&gt;</filepath> for
+Carbide.c++). </p> <ul>
+<li id="GUID-1F256024-8210-5C50-8B18-0498C0D5C15F"><p> <b>ipcparent.exe:</b> Executable
+of the parent process. </p> </li>
+<li id="GUID-1C755509-96FA-510A-944B-3FEA065C9936"><p> <b>ipcchild.exe:</b> Executable
+of the child process created using the <xref href="GUID-A9DB6E7C-B8D6-377A-BBE6-39E0A7A09E5D.dita"><apiname>popen()</apiname></xref> function. </p> </li>
+<li id="GUID-C056BC80-D664-5F25-A730-35220CA0A6B5"><p> <b>fifochild.exe:</b> Executable
+of the child process created using the <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref> function. </p> </li>
+</ul> </section>
+<section><title>Runtime setting</title> <p>Two eshells must be opened before
+executing this example. The executable, <filepath>ipcparent.exe</filepath> is
+run in one eshell and the other eshell is used to run the child process <filepath>fifochild.exe</filepath>.
+You can switch between the two eshells by pressing <b>CTRL</b> +<b>ALT</b> +<b>SHIFT</b> +<b>T</b>. </p> </section>
+</conbody></concept>
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FCL/sftools/depl/docscontent