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Xdelta
Xdelta is a command line tool for delta encoding, which stores or transmits the difference (deltas) between sequential data, instead of entire files. This is similar to diff and patch, except diff computes and shows the difference between two complete files, while patch is primarily designed for human-readable text files; Xdelta is designed for binary files and does not generate human readable output. Xdelta was first released sometime before October 12, 1997 by Joshua MacDonald, who currently maintains the program. The algorithm of xdelta1 was based on the algorithm of rsync, developed by Andrew Tridgell, though it uses a smaller block size. Xdelta version 3 is primarily designed to work with streams following the standardized VCDIFF format, and it realized the compatibility among other delta encoding software which supports the VCDIFF format. It runs on Unix-like operating systems and Microsoft Windows Windows is a Product lining, product line of Proprietary software, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 compression, particularly where archival histories of changes are required (e.g., in revision control software). The differences are recorded in discrete files called "deltas" or "diffs". In situations where differences are small – for example, the change of a few words in a large document or the change of a few records in a large table – delta encoding greatly reduces data redundancy. Collections of unique deltas are substantially more space-efficient than their non-encoded equivalents. From a logical point of view, the difference between two data values is the information required to obtain one value from the other – see relative entropy. The difference between identical values (under some equivalence) is often called ''0'' or the ... [...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] |
C (programming Language)
C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted Central processing unit, CPUs. It has found lasting use in operating systems code (especially in Kernel (operating system), kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the most widely used programming langu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix-like
A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like Application software, application is one that behaves like the corresponding List of POSIX commands, Unix command or Unix shell, shell. Although there are general Unix philosophy, philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like. Some well-known examples of Unix-like operating systems include Linux, FreeBSD and OpenBSD. These systems are often used on servers as well as on personal computers and other devices. Many popular applications, such as the Apache HTTP Server, Apache web server and the Bash (Unix shell), Bash shell, are also designed to be used on Unix-like systems. Definition The Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sectors of the computing industry – Windows (unqualified) for a consumer or corporate workstation, Windows Server for a Server (computing), server and Windows IoT for an embedded system. Windows is sold as either a consumer retail product or licensed to Original equipment manufacturer, third-party hardware manufacturers who sell products Software bundles, bundled with Windows. The first version of Windows, Windows 1.0, was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). The name "Windows" is a reference to the windowing system in GUIs. The 1990 release of Windows 3.0 catapulted its market success and led to various other product families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Utility Software
Utility software is a program specifically designed to help manage and tune system or application software. It is used to support the computer infrastructure - in contrast to application software, which is aimed at directly performing tasks that benefit ordinary users. However, utilities often form part of the application . For example, a batch job may run user-written code to update a database and may then include a step that runs a utility to back up the database, or a job may run a utility to compress a disk before copying files. Although a basic set of utility programs is usually distributed with an operating system (OS), and this first party utility software is often considered part of the operating system, users often install replacements or additional utilities. Those utilities may provide additional facilities to carry out tasks that are beyond the capabilities of the operating system. Many utilities that might affect the entire computer system require the user to have el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apache License
The Apache License is a permissive free software license written by the Apache Software Foundation (ASF). It allows users to use the software for any purpose, to distribute it, to modify it, and to distribute modified versions of the software under the terms of the license, without concern for royalties. The ASF and its projects release their software products under the Apache License. The license is also used by many non-ASF projects. History Beginning in 1995, the Apache Group (later the Apache Software Foundation) released successive versions of the Apache HTTP Server. Its initial license was essentially the same as the original 4-clause BSD license, with only the names of the organizations changed, and with an additional clause forbidding derivative works from bearing the Apache name. In July 1999, the Berkeley Software Distribution accepted the argument put to it by the Free Software Foundation and retired their ''advertising clause'' (clause 3) to form the new 3-clau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diff
In computing, the utility diff is a data comparison tool that computes and displays the differences between the contents of files. Unlike edit distance notions used for other purposes, diff is line-oriented rather than character-oriented, but it is like Levenshtein distance in that it tries to determine the smallest set of deletions and insertions to create one file from the other. The utility displays the changes in one of several standard formats, such that both humans or computers can parse the changes, and use them for patching. Typically, ''diff'' is used to show the changes between two versions of the same file. Modern implementations also support binary files. The output is called a "diff", or a patch, since the output can be applied with the Unix program . The output of similar file comparison utilities is also called a "diff"; like the use of the word " grep" for describing the act of searching, the word ''diff'' became a generic term for calculating data difference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patch (Unix)
The computer tool patch is a Unix program that updates text files according to instructions contained in a separate file, called a ''patch file''. The patch file (also called a ''patch'' for short) is a text file that consists of a list of differences and is produced by running the related diff program with the original and updated file as arguments. Updating files with patch is often referred to as ''applying the patch'' or simply ''patching'' the files. History The original patch program was written by Larry Wall (who went on to create the Perl programming language) and posted to mod.sources (which later became comp.sources.unix) in May 1985. patch was added to XPG4, which later became POSIX. Wall's code remains the basis of "patch" programs provided in OpenBSD, FreeBSD, and schilytools. The Open Software Foundation, which merged into The Open Group, is said to have maintained a derived version. The GNU project/ FSF maintains its patch, forked from the Larry Wall version. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Files
A binary file is a computer file that is not a text file. The term "binary file" is often used as a term meaning "non-text file". Many binary file formats contain parts that can be interpreted as text; for example, some computer document files containing formatted text, such as older Microsoft Word document files, contain the text of the document but also contain formatting information in binary form. Background and terminology All modern computers store information in the form of bits (binary digits), using binary code. For this reason, all data stored on a computer is, in some sense, "binary". However, one particularly useful and ubiquitous type of data stored on a computer is one in which the bits represent text, by way of a character encoding. Those files are called " text files" and files which are not like that are referred to as "binary files", as a sort of retronym or hypernym. Some "text files" contain portions that are actually binary data, and many "binary file ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rsync
rsync (remote sync) is a utility for transferring and synchronizing files between a computer and a storage drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like operating systems and is under the GPL-3.0-or-later license. rsync is written in C as a single- threaded application. The rsync algorithm is a type of delta encoding, and is used for minimizing network usage. Zstandard, LZ4, or Zlib may be used for additional data compression, and SSH or stunnel can be used for security. rsync is typically used for synchronizing files and directories between two different systems. For example, if the command rsync local-file user@remote-host:remote-file is run, rsync will use SSH to connect as user to remote-host. Once connected, it will invoke the remote host's rsync and then the two programs will determine what parts of the local file need to be transferred so that the remote file matches the local one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andrew Tridgell
Andrew "Tridge" Tridgell (born 28 February 1967) is an Australian computer programmer. He is the author of and a contributor to the Samba (software), Samba file server, and co-inventor of the rsync algorithm. He has analysed complex proprietary protocols and algorithms, to allow compatible free and open source software implementations. Projects Tridgell was a major developer of the Samba software, analyzing the Server Message Block protocol used for Workgroup (computer networking), workgroup and network file sharing by Microsoft Windows products. He developed thhierarchical memory allocator, originally as part of Samba. For his PhD dissertation, he co-developed rsync, including the rsync algorithm, a highly efficient file transfer and File synchronization, synchronisation tool. He was also the original author of rzip, which uses a similar algorithm to rsync. He developed spamsum, based on locality-sensitive hashing algorithms. He is the author of KnightCap, a reinforcement l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
