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<html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><!--Converted with jLaTeX2HTML 2002 (1.62) JA patch-1.4patched version by: Kenshi Muto, Debian Project.LaTeX2HTML 2002 (1.62),original version by: Nikos Drakos, CBLU, University of Leeds* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan* with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --><HTML><HEAD><TITLE>10.6.2 The recv() and timeout() Methods</TITLE><META NAME="description" CONTENT="10.6.2 The recv() and timeout() Methods"><META NAME="keywords" CONTENT="everything"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"><META NAME="Generator" CONTENT="jLaTeX2HTML v2002 JA patch-1.4"><META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"><LINK REL="STYLESHEET" HREF="everything.css" tppabs="http://www.isi.edu/nsnam/ns/doc/everything.css"><LINK REL="next" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html"><LINK REL="previous" HREF="node114.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node114.html"><LINK REL="up" HREF="node113.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node113.html"><LINK REL="next" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html3070" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html3064" HREF="node113.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node113.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html3058" HREF="node114.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node114.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html3066" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html3068" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html3071" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html">10.6.3 Linking the ``ping''</A><B> Up:</B> <A NAME="tex2html3065" HREF="node113.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node113.html">10.6 Creating a New</A><B> Previous:</B> <A NAME="tex2html3059" HREF="node114.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node114.html">10.6.1 Example: A ``ping''</A>   <B> <A NAME="tex2html3067" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html3069" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H2><A NAME="SECTION03762000000000000000"></A><A NAME="sec:agents:exmethods"></A><BR>10.6.2 The <TT>recv</TT>() and <TT>timeout</TT>() Methods</H2><P>The []recv method is not defined here, as this agentrepresents a request function and will generally not be receivingevents or packets<A NAME="tex2html18" HREF="footnode.html#foot4419" tppabs="http://www.isi.edu/nsnam/ns/doc/footnode.html#foot4419"><SUP>10.1</SUP></A>.By not defining the []recv method, the base class versionof []recv (, []Connector::recv) is used.The []timeout method is used to periodically send request packets.The following []timeout method is used, along with a helpermethod, []sendit:<PRE> void ECHO_Agent::timeout(int) { sendit(); echo_timer_.resched(interval_); } void ECHO_Agent::sendit() { Packet* p = allocpkt(); ECHOHeader *eh = ECHOHeader::access(p-\>bits()); eh-\>timestamp() = Scheduler::instance().clock(); send(p, 0); // Connector::send() } void ECHO_Timer::expire(Event *e) { a_-\>timeout(0); }</PRE>The []timeout method simply arranges for []sendit to beexecuted every <TT>interval_</TT> seconds.The []sendit method creates a new packet with most of itsheader fields already set up by []allocpkt.The packet is only lacks the current time stamp. The call to []access provides for a structured interface to thepacket header fields, and is used to set the timestamp field.Note that this agent uses its own special header (``ECHOHeader'').The creation and use of packet headers is described inlater chapterChapterchap:pformat;to send the packet to the next downstream node, []Connector::sendis invoked without a handler.<P><HR><!--Navigation Panel--><A NAME="tex2html3070" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html3064" HREF="node113.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node113.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html3058" HREF="node114.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node114.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html3066" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html3068" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html3071" HREF="node116.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node116.html">10.6.3 Linking the ``ping''</A><B> Up:</B> <A NAME="tex2html3065" HREF="node113.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node113.html">10.6 Creating a New</A><B> Previous:</B> <A NAME="tex2html3059" HREF="node114.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node114.html">10.6.1 Example: A ``ping''</A>   <B> <A NAME="tex2html3067" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html3069" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <!--End of Navigation Panel--><ADDRESS>2003-09-23</ADDRESS></BODY></HTML>⌨️ 快捷键说明
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