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Timestamp
A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolute notion of time, however. They can have any epoch, can be relative to any arbitrary time, such as the power-on time of a system, or to some arbitrary time in the past. The term "timestamp" derives from rubber stamps used in offices to stamp the current date, and sometimes time, in ink on paper documents, to record when the document was received. Common examples of this type of timestamp are a postmark on a letter or the "in" and "out" times on a time card. In modern times usage of the term has expanded to refer to digital date and time information attached to digital data. For example, computer files contain timestamps that tell when the file was last modified, and digital cameras add timestamps to the pictures they take, recordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trusted Timestamping
Trusted timestamping is the process of securely keeping track of the creation and modification time of a document. Security here means that no one—not even the owner of the document—should be able to change it once it has been recorded provided that the timestamper's integrity is never compromised. The administrative aspect involves setting up a publicly available, trusted timestamp management infrastructure to collect, process and renew timestamps. History The idea of timestamping information is centuries old. For example, when Robert Hooke discovered Hooke's law in 1660, he did not want to publish it yet, but wanted to be able to claim priority. So he published the anagram ''ceiiinosssttuv'' and later published the translation ''ut tensio sic vis'' (Latin for "as is the extension, so is the force"). Similarly, Galileo first published his discovery of the phases of Venus in the anagram form. Sir Isaac Newton, in responding to questions from Leibniz in a letter in 1677, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamp-based Concurrency Control
In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some databases to safely handle transactions, using timestamps. Operation Assumptions * Every timestamp value is unique and accurately represents an instant in time. * A higher-valued timestamp occurs later in time than a lower-valued timestamp. Generating a timestamp A number of different ways have been used to generate timestamp * Use the value of the system's clock at the start of a transaction as the timestamp. * Use a thread-safe shared counter that is incremented at the start of a transaction as the timestamp. * A combination of the above two methods. Formal Each transaction (T_i) is an ordered list of actions (A_). Before the transaction performs its first action (A_), it is marked with the current timestamp, or any other strictly totally ordered sequence: TS(T_i) = NOW(). Every transaction is also given an initially empty set of transactions upon wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix Time
Current Unix time () Unix time is a date and time representation widely used in computing. It measures time by the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the beginning of the Unix epoch, less adjustments made due to leap seconds. Unix time originated as the system time of Unix operating systems. It has come to be widely used in other computer operating systems, file systems, programming languages, and databases. Definition Two layers of encoding make up Unix time. The first layer encodes a point in time as a scalar real number which represents the number of seconds that have passed since 00:00:00UTC on Thursday, 1 January 1970. The second layer encodes that number as a sequence of bits or decimal digits. Unix time differs from both Coordinated Universal Time (UTC) and International Atomic Time (TAI) in its handling of leap seconds. UTC includes leap seconds that adjust for the discrepancy between precise time, as measured by atomi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linked Timestamping
Linked timestamping is a type of trusted timestamping where issued time-stamps are related to each other. Description Linked timestamping creates time-stamp tokens which are dependent on each other, entangled in some authenticated data structure. Later modification of the issued time-stamps would invalidate this structure. The temporal order of issued time-stamps is also protected by this data structure, making backdating of the issued time-stamps impossible, even by the issuing server itself. The top of the authenticated data structure is generally ''published'' in some hard-to-modify and widely witnessed media, like printed newspaper or public blockchain. There are no (long-term) private keys in use, avoiding PKI-related risks. Suitable candidates for the authenticated data structure include: * Linear hash chain * Merkle tree (binary hash tree) * Skip list The simplest linear hash chain-based time-stamping scheme is illustrated in the following diagram: The linking-based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamping (computing)
In computing timestamping refers to the use of an electronic timestamp to provide a temporal order among a set of events. Timestamping techniques are used in a variety of computing fields, from network management and computer security to concurrency control.''Computer aided verification: 13th International conference'', by Gérard Berry, Hubert Comon, A. Finkel 2001 page 423 For instance, a heartbeat network uses timestamping to monitor the nodes on a high availability computer cluster.''Theoretical Aspects of Distributed Computing in Sensor Networks'' by Sotiris Nikoletseas and José D.P. Rolim 2011 page 304 Timestamping computer files (updating the timestamp in the per-file metadata every time a file is modified) makes it possible to use efficient build automation tools. See also * Trusted timestamping * Timestamp-based concurrency control In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamping (computing)
In computing timestamping refers to the use of an electronic timestamp to provide a temporal order among a set of events. Timestamping techniques are used in a variety of computing fields, from network management and computer security to concurrency control.''Computer aided verification: 13th International conference'', by Gérard Berry, Hubert Comon, A. Finkel 2001 page 423 For instance, a heartbeat network uses timestamping to monitor the nodes on a high availability computer cluster.''Theoretical Aspects of Distributed Computing in Sensor Networks'' by Sotiris Nikoletseas and José D.P. Rolim 2011 page 304 Timestamping computer files (updating the timestamp in the per-file metadata every time a file is modified) makes it possible to use efficient build automation tools. See also * Trusted timestamping * Timestamp-based concurrency control In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stat (system Call)
is a Unix system call that returns file attributes about an inode. The semantics of vary between operating systems. As an example, Unix command uses this system call to retrieve information on files that includes: * atime: time of last access () * mtime: time of last modification () * ctime: time of last status change () stat appeared in Version 1 Unix. It is among the few original Unix system calls to change, with Version 4's addition of group permissions and larger file size. stat() functions The C POSIX library header , found on POSIX and other Unix-like operating systems, declares the stat() functions, as well as related functions called fstat() and lstat(). The functions take a struct stat buffer argument, which is used to return the file attributes. On success, the functions return zero, and on error, −1 is returned and errno is set appropriately. The stat() and lstat() functions take a filename argument. If the file is a symbolic link, stat() returns attri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO 8601
ISO 8601 is an international standard covering the worldwide exchange and communication of date and time-related data. It is maintained by the Geneva-based International Organization for Standardization (ISO) and was first published in 1988, with updates in 1991, 2000, 2004, and 2019, and an amendment in 2022. The standard provides a well-defined, unambiguous method of representing calendar dates and times in worldwide communications, especially to avoid misinterpreting numeric dates and times when such data is transferred between countries with different conventions for writing numeric dates and times. ISO 8601 applies to these representations and formats: ''dates,'' in the Gregorian calendar (including the proleptic Gregorian calendar); ''times,'' based on the 24-hour timekeeping system, with optional UTC offset; ''time intervals''; and combinations thereof.ISO 8601:2004 section 1 Scope The standard does not assign specific meaning to any element of the dates/times ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Version Control Software
In software development, version control is a class of systems responsible for managing changes to computer programs or other collections of information such that revisions have a logical and consistent organization. The following tables include general and technical information on notable version control and software configuration management (SCM) software. For SCM software not suitable for source code, see Comparison of open-source configuration management software. General information Table explanation *''Repository model'' describes the relationship between various copies of the source code repository. In a client–server model, users access a master repository via a client; typically, their local machines hold only a working copy of a project tree. Changes in one working copy must be committed to the master repository before they are propagated to other users. In a distributed model, repositories act as peers, and users typically have a local repository with version hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Archiver
A file archiver is a computer program that combines a number of files together into one archive file, or a series of archive files, for easier transportation or storage. File archivers may employ lossless data compression in their archive formats to reduce the size of the archive. Basic archivers just take a list of files and concatenate their contents sequentially into archives. The archive files need to store metadata, at least the names and lengths of the original files, if proper reconstruction is possible. More advanced archivers store additional metadata, such as the original timestamps, file attributes or access control lists. The process of making an archive file is called ''archiving'' or ''packing''. Reconstructing the original files from the archive is termed ''unarchiving'', ''unpacking'' or ''extracting''. History An early archiver was the Multics command ''archive'', descended from the CTSS command of the same name, which was a basic archiver and performed no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postmark
A postmark is a postal marking made on an envelope, parcel, postcard or the like, indicating the place, date and time that the item was delivered into the care of a postal service, or sometimes indicating where and when received or in transit. Modern postmarks are often applied simultaneously with the cancellation or killer that marks postage stamps as having been used. Sometimes a postmark alone is used to cancel stamps, and the two terms are often used interchangeably. Postmarks may be applied by handstamp or machine, using methods such as rollers or inkjets, while digital postmarks are a recent innovation. History The first postmark, called the "Bishop mark", was introduced by English Postmaster General Henry Bishop in 1661 and showed only the day and month of mailing to prevent the delay of the mail by carriers. In England during the latter part of the 17th century, several postmarks were devised for use with the London Penny Post, a postal system that delivered m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File System
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stopped and the next began, or where any piece of data was located when it was time to retrieve it. By separating the data into pieces and giving each piece a name, the data are easily isolated and identified. Taking its name from the way a paper-based data management system is named, each group of data is called a " file". The structure and logic rules used to manage the groups of data and their names is called a "file system." There are many kinds of file systems, each with unique structure and logic, properties of speed, flexibility, security, size and more. Some file systems have been designed to be used for specific applications. For example, the ISO 9660 file system is desig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
