Binary delta compression is a technology used in
software deployment
Software deployment is all of the activities that make a software system available for use.
The general deployment process consists of several interrelated activities with possible transitions between them. These activities can occur on the S ...
for distributing
patch
Patch or Patches may refer to:
Arts, entertainment and media
* Patch Johnson, a fictional character from ''Days of Our Lives''
* Patch (''My Little Pony''), a toy
* "Patches" (Dickey Lee song), 1962
* "Patches" (Chairmen of the Board song) ...
es.
Explanation
Downloading large amounts of data over the Internet for software updates can induce high network traffic problems, especially when a network of computers is involved. ''Binary Delta Compression'' technology allows a major reduction of download size by only transferring the difference between the old and the new files during the update process.
Implementation
In real-world implementations, it is common to also use standard compression techniques (such as
Lempel-Ziv
LZ77 and LZ78 are the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978.
They are also known as LZ1 and LZ2 respectively. These two algorithms form the basis for many variations includin ...
) while compressing. This makes sense because LZW already works by referring back to re-used strings
ZDeltais a good example of this, as it is built from
ZLib
zlib ( or "zeta-lib", ) is a software library used for data compression. zlib was written by Jean-loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. zlib is also a ...
. The algorithm works by referring to common patterns not only in the file to be compressed, but also in a source file. The benefits of this are that even if there are few similarities between the original and the new file, a good
data compression ratio
Data compression ratio, also known as compression power, is a measurement of the relative reduction in size of data representation produced by a data compression algorithm. It is typically expressed as the division of uncompressed size by compresse ...
is attained.
See also
*
Delta encoding
Delta encoding is a way of storing or transmitting data in the form of '' differences'' (deltas) between sequential data rather than complete files; more generally this is known as data differencing. Delta encoding is sometimes called delta compre ...
*
Remote Differential Compression
Remote Differential Compression (RDC) is a client–server synchronization algorithm that allows the contents of two files to be synchronized by communicating only the differences between them. It was introduced with Microsoft Windows Server 2003 R ...
External links
White paper for Microsoft's implementation of BDC technology*
A binary delta compression used by google for rolling out its updates with less size
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Software distribution