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<META NAME="Author" CONTENT="James CE Johnson">
<TITLE>ACE Tutorial 009</TITLE>
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<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>Our new <A HREF="directed_client.cpp">directed_client.cpp</A>
is very much like our previous one. The primary difference is the
addition of a timeout to the recv() call so that we can exit somewhat gracefully
if the server doesn't like what we have to say.
<P>
<HR WIDTH="100%"><TT></TT>
<P><TT>#include "ace/SOCK_Dgram.h"</TT>
<BR><TT>#include "ace/INET_Addr.h"</TT><TT></TT>
<P><TT>static const u_short PORT = ACE_DEFAULT_SERVER_PORT;</TT><TT></TT>
<P><TT>int main (int argc, char *argv[])</TT>
<BR><TT>{</TT>
<BR><TT> ACE_INET_Addr local ((u_short) 0);</TT>
<BR><TT> ACE_INET_Addr remote (PORT, argc > 1 ? argv[1] : "localhost");</TT>
<BR><TT> ACE_SOCK_Dgram dgram;</TT><TT></TT>
<P><TT> if (dgram.open (local) == -1)</TT>
<BR><TT> {</TT>
<BR><TT> ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "open"),
-1);</TT>
<BR><TT> }</TT><TT></TT>
<P><TT> char buf[512];</TT><TT></TT>
<P><TT> /*</TT>
<BR><TT> In order to conform to the "protocol"
requried by the server,</TT>
<BR><TT> we allow the user to specify a signature.
A default matching</TT>
<BR><TT> the server's default is also available.</TT>
<BR><TT> */</TT>
<BR><TT> sprintf (buf, argc > 2 ? argv[2] : "Hello World!");</TT><TT></TT>
<P><TT> if (dgram.send (buf, strlen (buf) + 1, remote) == -1)</TT>
<BR><TT> {</TT>
<BR><TT> ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "send"),
-1);</TT>
<BR><TT> }</TT><TT></TT>
<P><TT> /*</TT>
<BR><TT> Because we may have sent a signature that
the server doesn't</TT>
<BR><TT> honor, we have to have some way to get
out of the recv().</TT>
<BR><TT> Most ACE objects that have potential for
infinite blocking</TT>
<BR><TT> give you the option of providing a timeout.
recv() is no</TT>
<BR><TT> exception. Here, we construct an
ACE_Time_Value representing</TT>
<BR><TT> two seconds and no micro-seconds.
If recv() fails to get</TT>
<BR><TT> a response within the two seconds, it
will return -1.</TT>
<BR><TT> */</TT>
<BR><TT> ACE_Time_Value timeout (2, 0);</TT>
<BR><TT> if (dgram.recv (buf, sizeof (buf), remote, 0, &timeout)
== -1)</TT>
<BR><TT> {</TT>
<BR><TT> ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "recv"),
-1);</TT>
<BR><TT> }</TT><TT></TT>
<P><TT> ACE_DEBUG ((LM_DEBUG, "(%P|%t) The server said (%s)\n", buf));</TT><TT></TT>
<P><TT> return (0);</TT>
<BR><TT>}</TT>
<P>
<HR WIDTH="100%">
<P>On the next page, we see that the directed_client gets similar upgrades.
<P>
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