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<title>Example: Create a server that uses spawn()</title>
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<h1 class="topictitle1">Example: Create a server that uses <span class="apiname">spawn()</span></h1>
<div><p>This example shows how to use the <span class="apiname">spawn()</span> API
to create a child process that inherits the socket descriptor from the parent. </p>
<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms
of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
<pre>/**************************************************************************/
/* Application creates an child process using spawn(). */
/**************************************************************************/
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;spawn.h&gt;
#define SERVER_PORT 12345
main (int argc, char *argv[])
{
int i, num, pid, rc, on = 1;
int listen_sd, accept_sd;
int spawn_fdmap[1];
char *spawn_argv[1];
char *spawn_envp[1];
struct inheritance inherit;
struct sockaddr_in addr;
/*************************************************/
/* If an argument was specified, use it to */
/* control the number of incoming connections */
/*************************************************/
if (argc &gt;= 2)
num = atoi(argv[1]);
else
num = 1;
/*************************************************/
/* Create an AF_INET stream socket to receive */
/* incoming connections on */
/*************************************************/
listen_sd = socket(AF_INET, SOCK_STREAM, 0);
if (listen_sd &lt; 0)
{
perror("socket() failed");
exit(-1);
}
/*************************************************/
/* Allow socket descriptor to be reuseable */
/*************************************************/
rc = setsockopt(listen_sd,
SOL_SOCKET, SO_REUSEADDR,
(char *)&amp;on, sizeof(on));
if (rc &lt; 0)
{
perror("setsockopt() failed");
close(listen_sd);
exit(-1);
}
/*************************************************/
/* Bind the socket */
/*************************************************/
memset(&amp;addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(SERVER_PORT);
addr.sin_addr.s_addr = htonl(INADDR_ANY);
rc = bind(listen_sd,
(struct sockaddr *)&amp;addr, sizeof(addr));
if (rc &lt; 0)
{
perror("bind() failed");
close(listen_sd);
exit(-1);
}
/*************************************************/
/* Set the listen back log */
/*************************************************/
rc = listen(listen_sd, 5);
if (rc &lt; 0)
{
perror("listen() failed");
close(listen_sd);
exit(-1);
}
/*************************************************/
/* Inform the user that the server is ready */
/*************************************************/
printf("The server is ready\n");
/*************************************************/
/* Go through the loop once for each connection */
/*************************************************/
for (i=0; i &lt; num; i++)
{
/**********************************************/
/* Wait for an incoming connection */
/**********************************************/
printf("Interation: %d\n", i+1);
printf(" waiting on accept()\n");
accept_sd = accept(listen_sd, NULL, NULL);
if (accept_sd &lt; 0)
{
perror("accept() failed");
close(listen_sd);
exit(-1);
}
printf(" accept completed successfully\n");
/**********************************************/
/* Initialize the spawn parameters */
/* */
/* The socket descriptor for the new */
/* connection is mapped over to descriptor 0 */
/* in the child program. */
/**********************************************/
memset(&amp;inherit, 0, sizeof(inherit));
spawn_argv[0] = NULL;
spawn_envp[0] = NULL;
spawn_fdmap[0] = accept_sd;
/**********************************************/
/* Create the worker job */
/**********************************************/
printf(" creating worker job\n");
pid = spawn("/QSYS.LIB/QGPL.LIB/WRKR1.PGM",
1, spawn_fdmap, &amp;inherit,
spawn_argv, spawn_envp);
if (pid &lt; 0)
{
perror("spawn() failed");
close(listen_sd);
close(accept_sd);
exit(-1);
}
printf(" spawn completed successfully\n");
/**********************************************/
/* Close down the incoming connection since */
/* it has been given to a worker to handle */
/**********************************************/
close(accept_sd);
}
/*************************************************/
/* Close down the listen socket */
/*************************************************/
close(listen_sd);
}</pre>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="xspawn.htm" title="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.">Example: Use the spawn() API to create child processes</a></div>
</div>
<div class="relref"><strong>Related reference</strong><br />
<div><a href="spwnwrkr.htm" title="This example contains the code that enables the worker job to receive a data buffer from the client job and echo it back.">Example: Enable the worker job to receive a data buffer</a></div>
</div>
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