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Shared Dictionary Compression Over HTTP
SDCH (Shared Dictionary Compression for HTTP) is a data compression algorithm created by Google, based on VCDIFF (RFC 3284). SDCH achieves its effectiveness by using pre-negotiated dictionaries to "warm up" its internal state prior to encoding or decoding. These may either be already stored locally, or uploaded from a source and then cached. It was supported natively in Google Chrome, Chromium, and Android, as well as on Google websites. SDCH compression was removed from Google Chrome, and other Chromium products, in version 59 (2017-06-05). See also *Brotli *HTTP compression *SPDY SPDY (pronounced "speedy") is an obsolete open-specification communication protocol developed for transporting web content. SPDY became the basis for HTTP/2 specification. However, HTTP/2 diverged from SPDY and eventually HTTP/2 subsumed all us ... References {{Algorithm-stub Data compression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google
Google LLC () is an American multinational technology company focusing on search engine technology, online advertising, cloud computing, computer software, quantum computing, e-commerce, artificial intelligence, and consumer electronics. It has been referred to as "the most powerful company in the world" and one of the world's most valuable brands due to its market dominance, data collection, and technological advantages in the area of artificial intelligence. Its parent company Alphabet is considered one of the Big Five American information technology companies, alongside Amazon, Apple, Meta, and Microsoft. Google was founded on September 4, 1998, by Larry Page and Sergey Brin while they were PhD students at Stanford University in California. Together they own about 14% of its publicly listed shares and control 56% of its stockholder voting power through super-voting stock. The company went public via an initial public offering (IPO) in 2004. In 2015, Google was reor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VCDIFF
VCDIFF is a format and an algorithm for delta encoding, described in IETF'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 algorithms in "Delta encoding in HTTP"RFC 3229 and was employed in Google's Shared Dictionary Compression Over HTTP technology, formerly used in their Chrome browser. Delta instructions VCDIFF has 3 delta instructions. ADD, COPY, and RUN. ADD adds a new sequence, COPY copies from an old sequence, and RUN adds repeated data. Implementations Free software implementations include xdelta (version 3) and open-vcdiff. * Google's Shared Dictionary Compression Over HTTP proposal uses this algorithm, and was included in the Google Chrome browser, up to version 58. * xdelta - A tool, which is an Open Source VCDIFF delta compression implementation google/open-vcdiff- Another Open Source VCDIFF delta compression implementation as part ovc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google Chrome
Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS, iOS, and also for Android, where it is the default browser. The browser is also the main component of ChromeOS, where it serves as the platform for web applications. Most of Chrome's source code comes from Google's free and open-source software project ''Chromium'', but Chrome is licensed as proprietary freeware. WebKit was the original rendering engine, but Google eventually forked it to create the Blink engine; all Chrome variants except iOS now use Blink. , StatCounter estimates that Chrome has a 67% worldwide browser market share (after peaking at 72.38% in November 2018) on personal computers (PC), is most used on tablets (having surpassed Safari), and is also dominant on smartphones and at 65% across all platforms combined. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brotli
Brotli is a lossless data compression algorithm developed by Google. It uses a combination of the general-purpose LZ77 lossless compression algorithm, Huffman coding and 2nd-order context modelling. Brotli is primarily used by web servers and content delivery networks to compress HTTP content, making internet websites load faster. A successor to gzip, it is supported by all major web browsers and has become increasingly popular, as it provides better compression than gzip. Browsers currently support it over HTTPS only. History Google employees Jyrki Alakuijala and Zoltán Szabadka initially developed Brotli in 2013 to decrease the size of transmissions of WOFF web font. Alakuijala and Szabadka completed the Brotli specification during 20132016. The specification was accompanied with a reference implementation developed by two additional authors, Evgenii Kliuchnikov and Lode Vandevenne, who had previously developed Google's zopfli implementation of deflate and gzip compati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HTTP Compression
HTTP compression is a capability that can be built into web servers and web clients to improve transfer speed and bandwidth utilization. HTTP data is compressed before it is sent from the server: compliant browsers will announce what methods are supported to the server before downloading the correct format; browsers that do not support compliant compression method will download uncompressed data. The most common compression schemes include gzip and Brotli; a full list of available schemes is maintained by the IANA. There are two different ways compression can be done in HTTP. At a lower level, a Transfer-Encoding header field may indicate the payload of an HTTP message is compressed. At a higher level, a Content-Encoding header field may indicate that a resource being transferred, cached, or otherwise referenced is compressed. Compression using Content-Encoding is more widely supported than Transfer-Encoding, and some browsers do not advertise support for Transfer-Encoding comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPDY
SPDY (pronounced "speedy") is an obsolete open-specification communication protocol developed for transporting web content. SPDY became the basis for HTTP/2 specification. However, HTTP/2 diverged from SPDY and eventually HTTP/2 subsumed all usecases of SPDY. After HTTP/2 was ratified as a standard, major implementers, including Google, Mozilla, and Apple, deprecated SPDY in favor of HTTP/2. Since 2021, no modern browser supports SPDY. Google announced SPDY in late 2009 and deployed in 2010. SPDY manipulates HTTP traffic, with particular goals of reducing web page load latency and improving web security. SPDY achieves reduced latency through compression, multiplexing, and prioritization, although this depends on a combination of network and website deployment conditions. The name "SPDY" is a trademark of Google and is not an acronym. History HTTP/2 was first discussed when it became apparent that SPDY was gaining traction with implementers (like Mozilla and nginx), and was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
