Background
----------

Graphit is a tool that reads time-based numeric data over a network
socket and plots it in near real-time.

Here's a screenshot:

  http://github.com/marktriggs/Graphit/blob/master/screenshot.png

I'm in the unfortunate position of being a systems administrator by
day, and that means keeping an eye on lots of different things--load
averages, number of Apache processes, number of threads for certain
applications, things like that.  Tools like RRDTool do a great job of
gathering and plotting data, but they're not really designed for
real-time visualisation.  I wanted something I could stare at in the
quieter moments.

Graphit uses the wonderful JFreeChart (http://www.jfree.org/jfreechart/)
to do its plotting.  The other bits (the easy bits) are Clojure code to
handle reading data from a socket, tracking multiple graphs, and that
sort of thing.


Building it
-----------

Thanks to the wonders Of Leiningen and Clojars this should be easy to
build.  The steps:

  1.  Get Leiningen from http://github.com/technomancy/leiningen and put
      the 'lein' script somewhere in your $PATH.

  2.  From graphit's root directory, run `lein uberjar'.  Lein will grab
      all required dependencies and produce a `graphit.jar'.

      Note: Thanks to Java's AWT madness you seem to need your DISPLAY
        environment variable set to even compile the thing.

  3.  Run the jar with, for example:

        java -jar graphit.jar --redraw 2000 --port 6666

      This will redraw all graphs once every two seconds, and will
      listen on port 666 for data.


Trying it out
-------------

Once Graphit is running, you can plot some random lines just by using
bash and netcat:

  #!/bin/bash

  while [ 1 ]; do
    for i in 1 2 3; do
      for j in 1 2 3; do
        echo -e "graph$i\t$j\t$RANDOM"
      done
    done
    sleep 1
  done | nc localhost 6666


And that's about all there is to know: you connect to Graphit on its
port, send it one-reading per line in either this format:

  name of graph[tab]name of line[tab]y value

or this one:

  name of graph[tab]x value[tab]name of line[tab]y value  

or if you want to do times:

  name of graph[tab]time string[tab]name of line[tab]y value[tab]SimpleDateFormat string


JFreeChart gives some niceties for free: you can drag a rectangle to
zoom in, hold down control and click+drag to pan around, right click to
get a context menu.  All sorts of wonderful things.

The end.  Thanks for reading.