<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 2008 (1.71) 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>Low Level Network Protocol</TITLE> <META NAME="description" CONTENT="Low Level Network Protocol"> <META NAME="keywords" CONTENT="developers"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META NAME="Generator" CONTENT="LaTeX2HTML v2008"> <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> <LINK REL="STYLESHEET" HREF="developers.css"> <LINK REL="next" HREF="General_Daemon_Protocol.html"> <LINK REL="previous" HREF="General.html"> <LINK REL="up" HREF="Daemon_Protocol.html"> <LINK REL="next" HREF="General_Daemon_Protocol.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html824" HREF="General_Daemon_Protocol.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html818" HREF="Daemon_Protocol.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html812" HREF="General.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html820" HREF="Contents.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html822" HREF="GNU_Free_Documentation_Lice.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html825" HREF="General_Daemon_Protocol.html">General Daemon Protocol</A> <B> Up:</B> <A NAME="tex2html819" HREF="Daemon_Protocol.html">Daemon Protocol</A> <B> Previous:</B> <A NAME="tex2html813" HREF="General.html">General</A> <B> <A NAME="tex2html821" HREF="Contents.html">Contents</A></B> <B> <A NAME="tex2html823" HREF="GNU_Free_Documentation_Lice.html">Index</A></B> <BR> <BR> <!--End of Navigation Panel--> <H1><A NAME="SECTION00620000000000000000"></A> <A NAME="1836"></A> <A NAME="1837"></A> <BR> Low Level Network Protocol </H1> <P> At the lowest level, the network protocol is handled by <B>BSOCK</B> packets which contain a lot of information about the status of the network connection: who is at the other end, etc. Each basic <B>Bacula</B> network read or write actually consists of two low level network read/writes. The first write always sends four bytes of data in machine independent byte order. If data is to follow, the first four bytes are a positive non-zero integer indicating the length of the data that follow in the subsequent write. If the four byte integer is zero or negative, it indicates a special request, a sort of network signaling capability. In this case, no data packet will follow. The low level BSOCK routines expect that only a single thread is accessing the socket at a time. It is advised that multiple threads do not read/write the same socket. If you must do this, you must provide some sort of locking mechanism. It would not be appropriate for efficiency reasons to make every call to the BSOCK routines lock and unlock the packet. <P> <HR> <!--Navigation Panel--> <A NAME="tex2html824" HREF="General_Daemon_Protocol.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html818" HREF="Daemon_Protocol.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html812" HREF="General.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html820" HREF="Contents.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html822" HREF="GNU_Free_Documentation_Lice.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html825" HREF="General_Daemon_Protocol.html">General Daemon Protocol</A> <B> Up:</B> <A NAME="tex2html819" HREF="Daemon_Protocol.html">Daemon Protocol</A> <B> Previous:</B> <A NAME="tex2html813" HREF="General.html">General</A> <B> <A NAME="tex2html821" HREF="Contents.html">Contents</A></B> <B> <A NAME="tex2html823" HREF="GNU_Free_Documentation_Lice.html">Index</A></B> <!--End of Navigation Panel--> <ADDRESS> 2012-01-24 </ADDRESS> </BODY> </HTML>
