116 lines
7.4 KiB
HTML
116 lines
7.4 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Use the spawn() API to create child processes" />
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<meta name="abstract" content="This example shows how a server program can use the spawn() API to create a child process that inherits the socket descriptor from the parent." />
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<meta name="description" content="This example shows how a server program can use the spawn() API to create a child process that inherits the socket descriptor from the parent." />
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<meta name="DC.Relation" scheme="URI" content="xcodesigns.htm" />
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<meta name="DC.Relation" scheme="URI" content="xspwnserver.htm" />
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<meta name="DC.Relation" scheme="URI" content="spwnwrkr.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/spawn.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/bind.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/socket.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/listen.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/accept.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/close.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/send.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/recv.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="xspawn" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Use the spawn() API to create child processes</title>
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</head>
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<body id="xspawn"><a name="xspawn"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Use the <span class="apiname">spawn()</span> API to create child processes</h1>
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<div><p>This example shows how a server program can use the <span class="apiname">spawn()</span> API
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to create a child process that inherits the socket descriptor from the parent. </p>
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<div class="section"><p>The server job waits for an incoming connection, and then calls <span class="apiname">spawn()</span> to
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create children jobs to handle the incoming connection. The child process
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inherits the following attributes with the <span class="apiname">spawn()</span> function:
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</p>
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<ul><li>The socket and file descriptors</li>
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<li>The signal mask</li>
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<li>The signal action vector</li>
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<li>The environment variables</li>
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</ul>
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<p>The following figure illustrates how the server, worker, and client
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jobs interact when the <span class="apiname">spawn()</span> server design is used.</p>
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</div>
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<div class="section"><br /><img src="rxab6504.gif" alt="Server, worker, and client job interaction when the spawn() server design is used." /><br /></div>
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<div class="section"><h4 class="sectiontitle">Flow of socket events: Server that uses <span class="apiname">spawn()</span> to
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accept and process requests</h4><p>The following sequence of the socket
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calls provides a description of the graphic. It also describes the relationship
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between the server and worker examples. Each set of flows contain links to
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usage notes on specific APIs. If you need more details on the use of a particular
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API, you can use these links. The first example uses the following socket
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calls to create a child process with the <span class="apiname">spawn()</span> function
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call:</p>
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<ol><li>The <span class="apiname">socket()</span> function returns a socket descriptor representing
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an endpoint. The statement also identifies that the INET (Internet Protocol)
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address family with the TCP transport (SOCK_STREAM) being used for this socket.</li>
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<li>After the socket descriptor is created, the <span class="apiname">bind()</span> function
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gets a unique name for the socket. </li>
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<li>The <span class="apiname">listen()</span> allows the server to accept incoming
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client connections. </li>
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<li>The server uses the <span class="apiname">accept()</span> function to accept an
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incoming connection request. The <span class="apiname">accept()</span> call block indefinitely
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waiting for the incoming connection to arrive.</li>
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<li>The <span class="apiname">spawn()</span> function initializes the parameters for
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a work job to handle incoming requests. In this example, the socket descriptor
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for the new connection is mapped over to descriptor 0 in the child program. </li>
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<li>In this example, the first <span class="apiname">close()</span> function closes
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the listening socket descriptor. The second <span class="apiname">close ()</span> call
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ends the accepted socket.</li>
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</ol>
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</div>
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<div class="section"><h4 class="sectiontitle">Socket flow of events: Worker job created by <span class="apiname">spawn()</span></h4><p>The
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second example uses the following sequence of function calls:</p>
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<ol><li>After the <span class="apiname">spawn()</span> function is called on the server,
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the <span class="apiname">recv() </span> function receives the data from the incoming
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connection.</li>
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<li>The <span class="apiname">send()</span> function echoes data back to the client.</li>
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<li>The <span class="apiname">close()</span> function ends the spawned worker job.</li>
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</ol>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="xspwnserver.htm">Example: Create a server that uses spawn()</a></strong><br />
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This example shows how to use the <span class="apiname">spawn()</span> API
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to create a child process that inherits the socket descriptor from the parent. </li>
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<li class="ulchildlink"><strong><a href="spwnwrkr.htm">Example: Enable the worker job to receive a data buffer</a></strong><br />
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This example contains the code that enables the worker job to receive a data buffer from the client job and echo it back.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="xcodesigns.htm" title="There are a number of ways that you can design a connection-oriented socket server on the iSeries. These example programs can be used to create your own connection-oriented designs.">Examples: Connection-oriented designs</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../apis/spawn.htm">spawn()</a></div>
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<div><a href="../apis/bind.htm">bind()</a></div>
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<div><a href="../apis/socket.htm">socket()</a></div>
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<div><a href="../apis/listen.htm">listen()</a></div>
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<div><a href="../apis/accept.htm">accept()</a></div>
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<div><a href="../apis/close.htm">close()</a></div>
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<div><a href="../apis/send.htm">send()</a></div>
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<div><a href="../apis/recv.htm">recv()</a></div>
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</div>
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</div>
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</body>
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</html>
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