Shared Dictionary Compression Over HTTP

Shared Dictionary Compression over HTTP (SDCH) is a data compression

Data compression

In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....

method aimed to reduce redundancy

Data redundancy

Data redundancy occurs in database systems which have a field that is repeated in two or more tables. For instance, in case when customer data is duplicated and attached with each product bought then redundancy of data is a known source of inconsistency, since customer might appear with different...

across HTTP responses proposed by Google

Google

Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

. This is implemented in Google Chrome

Google Chrome

Google Chrome is a web browser developed by Google that uses the WebKit layout engine. It was first released as a beta version for Microsoft Windows on September 2, 2008, and the public stable release was on December 11, 2008. The name is derived from the graphical user interface frame, or...

. This is proposed modification to HTTP/1.1. SDCH is using VCDIFF

VCDIFF

VCDIFF is a format and an algorithm for delta encoding, described in RFC 3284. The algorithm is based on Jon Bentley and Douglas McIlroy's paper "Data Compression Using Long Common Strings" written in 1999. VCDIFF is used as one of the delta encoding algorithm in "Delta encoding in HTTP" .- Delta...

(RFC 3284) for the compression.

External links

SDCH | Google Group
mod-sdch | Apache implementation of shared dictionary compression over http (note: project is inactive)

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