XML files compress really well

Because XML usually contains a lot of repetitive elements (noticably tags and attributes), they are like a compressor’s darling. Just zip a few of your XML files and you’ll see.

Now I kind of always thought that on nowadays webservers gzip compression is activated by default anyway. Which was wrong, at least for quite a bunch of servers I use.

Activate GZip compression

If your server installation contains the deflate module (which is the case for all of the ones I use), then you can simply add the following line to your .htaccess file:

# compress all html, plain text, xml, css and javascript:
AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css application/x-javascript

AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css application/x-javascript

http://www.gidnetwork.com/tools/gzip-test.php

I also like this one, although it only gives you little info on content-encoding. But very much on top of that :-)
http://www.wmtips.com/tools/info/

This little Firefox addon will tell you wether any site you visit has GZip activated:
https://addons.mozilla.org/en-US/firefox/addon/54647 (Content Encoding Detector)

Conclusion

HTML websites will profit a lot from this compression, as well as Flash sites (if just for your swfobject.js) that use textual communication. And best of all: it won’t need any kungfu effort on your side! And: practically all browsers support it. (I’ve only heard of problems with IE6, but then, you know, f*** IE6)

Update:

A more complete solution for your .htaccess file:

<IfModule mod_deflate.c>
	AddOutputFilterByType DEFLATE text/html
	AddOutputFilterByType DEFLATE text/xml
 
	AddOutputFilterByType DEFLATE image/x-icon
 
	AddOutputFilterByType DEFLATE text/css
 
	AddOutputFilterByType DEFLATE text/javascript
	AddOutputFilterByType DEFLATE application/javascript
	AddOutputFilterByType DEFLATE application/x-javascript
	AddOutputFilterByType DEFLATE text/x-js
	AddOutputFilterByType DEFLATE text/ecmascript
	AddOutputFilterByType DEFLATE application/ecmascript
	AddOutputFilterByType DEFLATE text/vbscript
	AddOutputFilterByType DEFLATE text/fluffscript
 
	AddOutputFilterByType DEFLATE image/svg+xml
	AddOutputFilterByType DEFLATE application/x-font-ttf
	AddOutputFilterByType DEFLATE application/x-font
	AddOutputFilterByType DEFLATE font/opentype
	AddOutputFilterByType DEFLATE font/otf
	AddOutputFilterByType DEFLATE font/ttf
	AddOutputFilterByType DEFLATE application/x-font-truetype
	AddOutputFilterByType DEFLATE application/x-font-opentype
	AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
	AddOutputFilterByType DEFLATE application/vnd.oasis.opendocument.formula-template
</IfModule>

(Source)

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1. 3D Point Cloud with Javascript and Canvas

There’s also one for Actionscript 3 (xpath-as3). But.. well… I wanted to go for some real speed! I like XPath a lot, but we now have native E4X selection in Actionscript 3, quite a different concept of node selection, and the conversion of XPath to E4X obviously results in quite a compromise in performance.

So all I need is a decent E4X parser. And hey, I found one! E4XParser from Digital Primates. It does its job really well, especially considering the very compact code it consists of. Thanks to some preparsing and caching, it’s also quite fast.

Still I thought I can do better :-) So I planted myself for a day (and a night) in front of my displays and hacked the hell out of it. The result is a little library which does pretty much the same thing as E4XParser, though pretty much more and a little faster too (15% to 50%). It’s about half as fast as the native E4X selection (once parsed). You can do nearly anything you can do with E4X. Use it like this:

import com.betabong.xml.e4x.E4X;
var result : XMLList = E4X.evaluate( xmllist , "author.( name.@last == 'Jobs' )" );
 
// E4X.evaluate( source : XMLList , expression : String ) : XMLList

 
If your source is XML, just do XMLList( xml ), if your result should be xml, do xml = result[0]

Test it here

Restrictions: You can’t use AND/OR in comparisions. So, this won’t go: author.( name.@first == ‘Steve’ && name.@last == ‘Jobs’ ) – though this is only a real limitations for OR. do this for AND: author.( name.@first == ‘Steve’ ).( name.@last == ‘Jobs’ ).

What you can do: Yes, you can do quite advanced stuff like author.( name.@first == name.@last ) or car.@rating.average() (one of the few proprietary functions I added). Or even

*..car.( @brand.toLowerCase() == 'volvo' ).( parent().( localName() == 'group' ).@rating > @rating )

– a weird example, I admit, but fancy, ain’t it? :-)

This is the first time ever I’m releasing part of my library as Open Source (MIT licence). As soon as I’ll find some time (and if I see any interest), I’m gonna put this into Google Code, so everybody can easily checkout and participate. Until then download it from here:

Download (zip 13kb)

Related posts:

1. Simplicity follows Performance – parsing Strings in Actionscript 3
2. Alchemy – THE cool new flash feature!
3. Nested inner functions can be evil