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<!-- $Id$ -->
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="GENERATOR" CONTENT="Mozilla/4.04 [en] (X11; I; Linux 2.0.32 i486) [Netscape]">
<META NAME="Author" CONTENT="James CE Johnson">
<TITLE>ACE Tutorial 009</TITLE>
</HEAD>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F">
<CENTER><B><FONT SIZE=+2>ACE Tutorial 009</FONT></B></CENTER>
<CENTER><B><FONT SIZE=+2>Sending and receiving datagrams again</FONT></B></CENTER>
<P>
<HR WIDTH="100%">
<P>Let's take a look at our new <A HREF="server.cpp">server.cpp</A> where
we add in just a bit of code to examine the datagram contents before responding.
<P>
<HR WIDTH="100%"><TT></TT>
<PRE>
<font color=red>// $Id$</font>
<font color=red>/* The actual datagram operations here are exactly the same as those
used in the previous tutorial. What we've added is some logic that
will prevent this server from responding to just any old datagram.
I'll limit my comments to those pieces of code. */</font>
<font color=blue>#include</font> "<A HREF="../../../ace/SOCK_Dgram.h">ace/SOCK_Dgram.h</A>"
<font color=blue>#include</font> "<A HREF="../../../ace/INET_Addr.h">ace/INET_Addr.h</A>"
static const u_short PORT = ACE_DEFAULT_SERVER_PORT;
<font color=red>/* In order to be more selective, our server will be started with a
"<font color=green>signature</font>". If none is given, we'll use the one here instead. */</font>
static const char *default_signature = "<font color=green>Hello World!</font>";
int
main (int argc, char *argv[])
{
ACE_INET_Addr local (PORT);
ACE_SOCK_Dgram dgram;
if (dgram.open (local) == -1)
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>%p\n</font>",
"<font color=green>open</font>"),
-1);
char buf[BUFSIZ];
ACE_INET_Addr remote;
while (dgram.recv (buf,
sizeof (buf),
remote) != -1)
{
<font color=red>/* What did the client say? */</font>
ACE_DEBUG ((LM_DEBUG,
"<font color=green>(%P|%t) Received (%s) from (%s)\n</font>",
buf,
remote.get_host_name ()));
<font color=red>/* Use a simple string-op to decide if the client is one of our
own. Of course, you could have sent numeric values or even a
struct of data. For this simple exercise, however, strings are
just fine. */</font>
if (<font color=#008888>ACE_OS::strcmp</font> (buf,
argc > 1 ? argv[1] : default_signature))
{
<font color=red>/* If the client didn't say something we like then log it
*and move on. /
ACE_DEBUG ((LM_DEBUG,
"<font color=green>(%P|%t) Client query does not match our signature (%s). Response not sent.\n</font>",
argc > 1 ? argv[1] : default_signature));
}
else
{
<font color=red>/* As before, we respond to the client's query. */</font>
ACE_INET_Addr local ((u_short) 0);
ACE_SOCK_Dgram peer;
if (peer.open (local) == -1)
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>%p\n</font>",
"<font color=green>response open</font>"),
-1);
sprintf (buf,
"<font color=green>I am here</font>");
if (peer.send (buf,
<font color=#008888>ACE_OS::strlen</font> (buf) + 1,
remote) == -1)
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>%p\n</font>",
"<font color=green>response send</font>"),
-1);
}
}
return 0;
}
</PRE>
<HR WIDTH="100%">
<P>Let's move on and see what changes the clients require...
<P><HR WIDTH="100%">
<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page03.html">Continue This Tutorial</A>]</CENTER>
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