On 12 December 2012 02:17, Michael Beatty <span dir="ltr"><<a href="mailto:Michael.Beatty@sherwin.com" target="_blank">Michael.Beatty@sherwin.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> What does the message look like and how big is it (excluding message text) ?</blockquote>
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> Is it XML?</blockquote><div><br></div><div>
No, it's raw text. When you send a status message from the command-line or in a script, the content of the text is sent to the server. There's no encoding, no compression, no conversion, no (added) headers, nothing but what you send. So a shell-based Xymon client clone can be constructed using telnet like so:</div>
<div><br></div><div>( echo "MSG"; sleep 1 ) | telnet $HOST $PORT</div><div><br></div><div>And the message on the wire looks like (depending on the test and message type):</div><div><br></div><div>status the,host,name.conn Thu Dec 25 00:00:01 UTC 2012</div>
<div>bla bla</div><div>yada yada</div><div><br></div><div>In standard Xymon/BB messages, there's no text sent back from the server. A "central" mode client is different - see later. There are different message types, which you can read about in the man page for the "xymon" command.</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> How is the connection made between the client and host? Are sockets made?</blockquote>
<div><br></div><div>Yes, as per above. Also see other examples: <a href="http://www.xymon.com/xymon/help/xymon-tips.html#noinstall">http://www.xymon.com/xymon/help/xymon-tips.html#noinstall</a></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
How does the server handle large volumes of connections. One thing I have read is that any bottle necks will be more likely with disk I/O than network traffic, is this fair?<br></blockquote><div><br></div><div>Probably, but I can't comment with any authority. I know that the Xymon daemon (xymond) keeps a lot of stuff in memory, with periodic snapshots written to disk, and so this probably improves performance significantly compared to Big Brother.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">The next part I'm not sure I understand correctly.... The sever then sends a response to the client that contains data that instructs the client what information it wants next time (this is taken from hosts.cfg?) The client then uses this response to determine which information to collect and send the next time the client is launched.</blockquote>
<div><br></div><div>There are potentially two parts to the client-server interaction. A client can have its own "ext" scripts that connect to the server and send an update on a single client-side test. This is not the default, and would need to be added on top of a standard Xymon client installation. For instance, my systems all have checks on the SMART disk status, which can only be done on the client side, and are not included in the standard client data.</div>
<div><br></div><div>The rest of the data sent to the server are concatenated into one long "client" message. This is all driven by the "xymonclient.sh" script, which in turn runs xymonclient-linux.sh (or whichever) and logfetch. The client connects to the server and sends a client data message looking like so:</div>
<div><br></div><div>client the,host,name.linux linux</div><div>[date]</div><div>Thu Dec 25 00:00:01 UTC 2012<br></div><div>[uname]</div><div>Linux <a href="http://the.host.name">the.host.name</a> 2.6.16.10-1.2.3-smp x86_64</div>
<div>...</div><div><br></div><div>This is exactly what you see when you click on the "Client data available" link at the bottom of some of the status pages (eg "conn").</div><div><br></div><div>Now, if the client is in "local mode", that's the end.</div>
<div><br></div><div>However, in "central mode", the client script wait for Xymon to send back some logfetch info. This is stored in the temporary logfetch configuration file, typically /tmp/logfetch.<name of server>.cfg. This contains the sections of client-local.cfg on the server that are relevant to the client. You can see the logfetch configuration by catting the temporary file, or you can fetch it yourself with the following command:</div>
<div><br></div><div>printf "[dummy]\ntesting\n" | $XYMON $XYMSRV 'client/dummyID name,of,host.linux linux'<br></div><div><br></div><div>Each time the xymonclient.sh script runs, it launches logfetch, which uses this temporary logfetch configuration to determine what to append to the client message to be sent back to Xymon. On each run, the configuration being used is from the last time xymonclient.sh was run, which is why there is a delay (of 5 to 10 minutes) in changes to client-local.cfg being picked up on the client.</div>
<div><br></div><div>The client knows nothing of the contents of hosts.cfg. (I think there's a way it can get it with a "hostinfo" message, but I don't believe any of the standard client scripts and binaries use this.) The content of the client message is pretty much governed by the commands in the xymonclient-linux.sh (or whatever) script, and logwatch and its configuration derived from client-local.cfg.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> So, aside from the server's ping test, all traffic is initiated by the client?<br>
</blockquote><div><br></div><div>Well, aside from the other network tests (ssh, telnet, http, etc) and other "ext" tests, yes that is correct.</div><div><br></div><div>J</div><div><br></div></div></div>