A couple of days ago I presented a "emulator" of sorts to run Google Wave gadgets without sandbox access because Google hadn't started giving out access yet. They have now, to Google IO attendees at least but not to the rest of us (or have they?) so I still don't have mine (hint, hint)

Anyway, what good would it do to write that gadget emulator without using it, so I've put together a very rough proof of concept for a shared graphics editor gadget using SVG. I didn't write all of it myself, mind you. Jayesh Salvi started a discussion about SVG in Wave, and during that discussion he pointed us to an existing open source browser based SVG editor by Narendra Sisodiya and Pavol Rusnak.

That made my job reasonably easy. I chopped their editor to pieces and stripped out a lot of stuff, partially to reduce the amount of work to make it work with Wave, partially to remove features that aren't quite finished yet.

The result is still buggy (clearing the canvas doesn't work; deletion is shaky), not as efficient as it could be (at the moment it re-sends all attributes of modified elements instead of just the changed ones, but that's easily fixed), lacks lots of features (like moving objects, saving, loading external SVG's etc.). 

More importantly, since I don't have sandbox access it has not been tested with the actually Google Wave client (hint, hint; any Google people reading this?) It is possible or even likely that it won't work in the real client, but any issues should be reasonable simple to fix.

It's been tested - somewhat - on Firefox and Safari. It is highly unlikely to work on Internet Explorer (it's possible it could work if you have an SVG plugin installed, but I doubt it). It could be made to work on IE via a shim layer to use VML instead of SVG, but that's not very high on my priority list at the moment - especially as Google looks set to introduce a suitable shim layer.

You can test it now by going to my gadget emulator, and entering the filename "svg-edit.xml".

If you want to experiment with the code on your own, get the latest version of my gadget emulator from the Github repository and the SVG editor gadget also from Github.

Not that while I welcome patches / suggestions, this is a proof of concept and I'm not sure how far I'll take it - I also have not talked to Narendra or Pavol about whether it's possible or desirable to fold any of the (fairly extensive) changes I made back into the original editor. If you'd like to see this turn into something more, let me hear about it in the comments.
UPDATE: I will be working with the SVG Edit guys to combined the two projects. Also see this post at The Next Web

(And if you're with the Google Wave team and want to give me sandbox access, e-mail me at vidar@hokstad.com or vidar.hokstad@gmail.com - I promise I'll use it to make sure this gadget runs properly in the actual client ;) )

Sliding Stats is a small little piece of code I'm working on to plug into any Rack enabled Ruby web app (and practically any Ruby web-framework can work with Rack these days) to give me glimpse of what's going on without having to tail referrer logs etc.
It doesn't do all that much, and I don't want it to: It keeps a "sliding window" of requests that doesn't match a list of criteria for things you want to ignore, and maintains a graph of referrers, pages, and referrers broken down by pages (the latter as a table). When the limit is hit, old requests are removed, so if you set the limit for the window low enough, you'll see a constantly changing view of where people are clicking through to your site from, and to what pages.

For an example of what it looks like, see my stats page

Since it ties in with Rack you can use this regardless of what web framework you use, as long as it has a Rack adapter. That means Rails, Merb, Sinatra, Camping and bunch of others.

The code is on GitHub. Installation instructions and a gem can be found at http://www.hokstad.com/slidingstats. Please note it has version number 0.2.3 for a reason, so don't try it out on any sites you worry about actually keeping running - I'm sure there are nasty bugs in there. Comments / suggestions welcome...

I don't plan on adding all that many enhancements to it - for "proper stats" I use Google Analytics - but I will tweak things like the filtering of requests, and I want to add an option to make the limit time based instead of just by number of queries. I'll probably clean up the CSS a bit too, and pretty up the SVG graphs.

To install it you'll need SVG::Graph installed - unfortunately I don't think there's any gems for that available.

UPDATE: Fixed some rather embarrassing bugs - if you downloaded 0.2.3 you may want to upgrade.

One thing that comes up time and time again when I mess around with a system, is quickly looking at frequencies of various things - for example disk usage by sub-directory, or referrer entries in my Apache access log.  Like this:http://librsvg.sourceforge.net/

# cat /var/log/httpd/access_log | cut -d' ' -f11 | grep -v '"-"' | grep -v hokstad.com | sort | uniq -c | sort -rn | head -n 10
 74 "http://www.google.com/reader/view/"
 42 "http://www.rubyflow.com/items/1606"
 35 "http://www.dzone.com/links/creating_graphviz_graphs_from_ruby_arrays.html"
 27 "http://www.dzone.com/links/rss/creating_graphviz_graphs_from_ruby_arrays.html"
 20 "http://www.reddit.com/r/ruby/"
 12 "http://www.reddit.com/r/ruby/comments/7tw1a/creating_graphviz_graphs_from_ruby_arrays/"
 9 "http://www.graphviz.org/Resources.php"
 8 "http://www.netvibes.com/"
 8 "http://www.google.com/reader/view/#overview-page"
 8 "http://www.google.com/notebook/fullpage"

Especially the "sort | uniq -c | sort -rn | head -n something" is a very frequently recurring pattern, in order to get a list of something in descending order of frequency.

But I'm difficult. I want something visual; a chart. Something like this:


Incidentally, there's a nice Ruby package called SVG::Graph that allows you to generate SVG's from this. The above is a PNG for best compatibility, but here is the SVG version - at least Firefox renders it better than rsvg which I used to generate the PNG.
Assuming you install SVG::Graph from the above page, it's pretty simple to generate the SVG's - just pipe the output from the above command straight into this script:

require 'SVG/Graph/BarHorizontal'
data = []
fields = []
ARGF.each do |line|
 line = line.chomp.split
 data << line[0].to_i
 fields << line[1]
end
graph = SVG::Graph::BarHorizontal.new(:height => 20 * data.size, :width => 800, :fields => fields.reverse)
graph.add_data(:data => data.reverse)
graph.rotate_y_labels = false
graph.scale_integers = true
graph.key = false
print graph.burn

It tries to be reasonably intelligent about adjusting the height of the graph, but you might want to adjust the width and other parameters. My goal was to get something simple that'll "just work" when I pipe the output of "uniq -c" into it, but any space separated data with a number first and the label afterwards should work as long as the data set is small enough that the graph it produces doesn't become ridiculously large. I'll probably extend it with some command line options, and I want to change the styles used to set colors etc., but the above is enough for 90% of what I want. Note that SVG::Graph also support pie charts, line charts etc.