deflate - Dave's Blog

HTTP Compression Documentation Reference

2012 Jun 13, 3:08

There's a lot of name reuse in HTTP compression so I've made the following to help myself keep it straight.

HTTP Content Coding Token	gzip	deflate	compress
	An encoding format produced by the file compression program "gzip" (GNU zip)	The "zlib" format as described in RFC 1950.	The encoding format produced by the common UNIX file compression program "compress".
Data Format	GZIP file format	ZLIB Compressed Data Format	The compress program's file format
Compression Method	Deflate compression method		LZW
	Deflate consists of LZ77 and Huffman coding

Compress doesn't seem to be supported by popular current browsers, possibly due to its past with patents.

Deflate isn't done correctly all the time. Some servers would send the deflate data format instead of the zlib data format and at least some versions of Internet Explorer expect deflate data format instead of zlib data format.

Encode-O-Matic: Guess Encoding

2010 Apr 4, 2:02

I've just updated Encode-O-Matic with a Guess Input Encoding feature. When you start Encode-O-Matic or when you use the 'Guess Input Encoding' menu item from the 'Tools' menu, Encode-O-Matic will try out various combinations of encodings and guess at which set seem to apply to your input. For instance given the following text, Encode-O-Matic will correctly guess that it is percent encoded, base64 encoded, deflate compressed text:

S%2BWqUEhLLMoFUulFpXnZQLogMa%2BkmCuPqxzILk%2FMyeHK4QIA

It should work fairly well for simple things but I did pick 'Guess' for the name of the feature to intentionally lower expectations. It doesn't currently apply to character encodings but that may be something to consider in the future.

technical encodeomatic tool encoding

Encode-O-Matic Update: Compression, Hex View, Quick Show Output

2010 Mar 9, 9:08

I've just put up an update for Encode-O-Matic with the following improvements:

Hex editor: the output and input views can now be switched between a UTF8 textbox view and a hex editor view. This is built using the free Be.HexEditor.
Compression: I've added the .NET GZip, deflate, and inflate streams to the list of supported encodings.
Quick Show Output: There are now 'Show Output' radio buttons next to each encoding in the encoding stack. Clicking on them changes the output view to show the output from that encoding in the stack. This lets you easily jump between different parts of your encoding process. Adding or removing an encoding to the stack resets the view.
Minor visuals improvement: added app icon, changed buttons with one word symbols to command names.

technical encodeomatic project

Coding Horror: You're Reading The World's Most Dangerous Programming Blog

2010 Jan 20, 8:28GZip vs Deflate execution speeds. Deflate found to be much faster in particular cases and about the same in the rest.

gzip deflate performance technical http compression programming development blog

RFC 1951 - DEFLATE Compressed Data Format Specification version 1.3

2009 Sep 3, 7:17"This specification defines a lossless compressed data format that compresses data using a combination of the LZ77 algorithm and Huffman coding." Also see RFC 1950 zlib, a wrapper compression format that can use deflate, and RFC 1952 gzip, a compressed file format that can use deflate.

technical rfc ietf compression http deflate gzip zlib

Timefire: On Reducing the Size of Compressed Javascript (by up to 20%)

2009 Sep 1, 4:39"...what effect does the large-scale structure of the JS output code have on the DEFLATE algorithm of GZIP which is used to serve up compressed script?" Another instance of using knowledge of the specific file type to get gains in compression. Is there a web proxy running all this at which I can point my phone?

via:kris.kowal performance javascript gzip deflate compression web technical