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Two-phase Commit Protocol
In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC, ''tupac'') is a type of Atomic commit, atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that participate in a Distributed transaction, distributed atomic transaction on whether to Commit (data management), commit or abort (roll back) the transaction. This protocol (a specialised type of Consensus (computer science), consensus protocol) achieves its goal even in many cases of temporary system failure (involving either process, network node, communication, etc. failures), and is thus widely used.Phil Bernstein, Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (1987) ''Concurrency Control and Recovery in Database Systems'' Chapter 7, Addison Wesley Publishing Company, Gerhard Weikum, Gottfried Vossen (2001) ''Transactional Information Systems'' Chapter 19, Elsevier, Philip A. Bernstein, Eric Newcomer (2009)''Principles of Transact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two Phase Commit Seq Diagram Success 01
2 (two) is a number, numeral (linguistics), numeral and numerical digit, digit. It is the natural number following 1 and preceding 3. It is the smallest and the only even prime number. Because it forms the basis of a Dualistic cosmology, duality, it has Religion, religious and Spirituality, spiritual significance in many Culture, cultures. Mathematics The number 2 is the second natural number after 1. Each natural number, including 2, is constructed by succession, that is, by adding 1 to the previous natural number. 2 is the smallest and the only even prime number, and the first Ramanujan prime. It is also the first superior highly composite number, and the first colossally abundant number. An integer is determined to be Parity (mathematics), even if it is Division (mathematics), divisible by two. When written in base 10, all Multiple (mathematics), multiples of 2 will end in 0, 2, 4, 6, or 8; more generally, in any even base, even numbers will end with an even digit. A dig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stable Storage
Stable storage is a classification of computer data storage technology that guarantees atomicity for any given write operation and allows software to be written that is robust against some hardware and power failures. To be considered atomic, upon reading back a just written-to portion of the disk, the storage subsystem must return either the write data or the data that was on that portion of the disk before the write operations. Most computer disk drives are not considered stable storage because they do not guarantee atomic write; an error could be returned upon subsequent read of the disk where it was just written to in lieu of either the new or prior data. Implementation Multiple techniques have been developed to achieve the atomic property from weakly atomic devices such as disks. Writing data to a disk in two places in a specific way is one technique and can be done by application software. Most often though, stable storage functionality is achieved by mirroring data on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two Generals' Problem
In computing, the Two Generals' Problem is a thought experiment meant to illustrate the pitfalls and design challenges of attempting to coordinate an action by communicating over an unreliable link. In the experiment, two generals are only able to communicate with one another by sending a messenger through enemy territory. The experiment asks how they might reach an agreement on the time to launch an attack, while knowing that any messenger they send could be captured. The Two Generals' Problem appears often as an introduction to the more general Byzantine Generals problem in introductory classes about computer networking (particularly with regard to the Transmission Control Protocol, where it shows that TCP cannot guarantee state consistency between endpoints and why this is the case), though it applies to any type of two-party communication where failures of communication are possible. A key concept in epistemic logic, this problem highlights the importance of common knowledge. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raft (algorithm)
Raft is a consensus algorithm designed as an alternative to the Paxos family of algorithms. It was meant to be more understandable than Paxos by means of separation of logic, but it is also formally proven safe and offers some additional features. Raft offers a generic way to distribute a state machine across a cluster of computing systems, ensuring that each node in the cluster agrees upon the same series of state transitions. It has a number of open-source reference implementations, with full-specification implementations in Go, C++, Java, and Scala. It is named after Reliable, Replicated, Redundant, And Fault-Tolerant. Raft is not a Byzantine fault tolerant (BFT) algorithm; the nodes trust the elected leader. Basics Raft achieves consensus via an elected leader. A server in a raft cluster is either a ''leader'' or a ''follower'', and can be a ''candidate'' in the precise case of an election (leader unavailable). The leader is responsible for log replication to the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paxos Algorithm
Paxos is a family of protocols for solving Consensus (computer science), consensus in a network of unreliable or fallible processors. Consensus is the process of agreeing on one result among a group of participants. This problem becomes difficult when the participants or their communications may experience failures. Consensus protocols are the basis for the state machine replication approach to distributed computing, as suggested by Leslie Lamport and surveyed by Fred B. Schneider, Fred Schneider. State machine replication is a technique for converting an algorithm into a fault-tolerant, distributed implementation. Ad-hoc techniques may leave important cases of failures unresolved. The principled approach proposed by Lamport et al. ensures all cases are handled safely. The Paxos protocol was first submitted in 1989 and named after a fictional legislative consensus system used on the Paxi, Paxos island in Greece, where Lamport wrote that the parliament had to function "even thou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-phase Commit Protocol
In computer networking and distributed databases, the three-phase commit protocol (3PC) is a distributed algorithm that ensures all nodes in a system agree to commit or abort a transaction. It improves upon the two-phase commit protocol (2PC) by eliminating the possibility of indefinite blocking caused by a specific type of failure during the commit phase. Motivation A two-phase commit protocol cannot dependably recover from a failure of both the coordinator and a cohort member during the Commit phase. If only the coordinator had failed, and no cohort members had received a commit message, it could safely be inferred that no commit had happened. If, however, both the coordinator and a cohort member failed, it is possible that the failed cohort member was the first to be notified, and had actually done the commit. Even if a new coordinator is selected, it cannot confidently proceed with the operation until it has received an agreement from all cohort members, and hence must bloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yoav Raz
Yoav () is a male given name popular among Israeli Jews. Its popularity is attributed to both Joab (), commander of King David's army in the Hebrew Bible, and Yitzhak Dubno, a 1940s Palmach soldier whose codename was Yoav. Yoav is also the namesake of two Israeli settlements: Yoav Regional Council (including Sde Yoav, a kibbutz) in the Southern District, named after Yitzhak "Yoav" Dubno; and Givat Yoav, a moshav in the Golan Heights, named after Israeli soldier Yoav Shaham who died during the Samu incident. Notable people with the name Yoav include: * Yoav Avni (born 1969), Israeli author * Yoav Bear (born 1991), Israeli cyclist * Yoav Benjamini (born 1949), Israeli statistician * Yoav Ben-Tzur (born 1958), Israeli politician and acting Minister of Health * Yoav Bruck (born 1972), Israeli swimmer * Yoav Chelouche (born 1953), Israeli businessman * Yoav Cohen (born 1999), Israeli windsurfer * Yoav Dothan (born 1955), Israeli chess player * Yoav Eliasi (born 1977), Israeli rappe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Network
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or by wireless communication. The devices may be connected in a variety of network topologies. In order to communicate over the network, computers use agreed-on rules, called communication protocols, over whatever medium is used. The computer network can include personal computers, Server (computing), servers, networking hardware, or other specialized or general-purpose Host (network), hosts. They are identified by network addresses and may have hostnames. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree (data Structure)
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, except for the ''root'' node, which has no parent (i.e., the root node as the top-most node in the tree hierarchy). These constraints mean there are no cycles or "loops" (no node can be its own ancestor), and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes (parent and children nodes of a node under consideration, if they exist) in a single straight line (called edge or link between two adjacent nodes). Binary trees are a commonly used type, which constrain the number of children for each parent to at most two. Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an application associated with the database. Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X/Open XA
For transaction processing in computing, the X/Open XA standard (short for "eXtended Architecture") is a specification released in 1991 by X/Open (which later merged with The Open Group) for distributed transaction processing (DTP). Goals The goal of XA is to guarantee atomicity in "global transactions" that are executed across heterogeneous components. A ''transaction'' is a unit of work such as transferring money from one person to another. Distributed transactions update multiple data stores (such as databases, application servers, message queues, transactional caches, etc.). To guarantee integrity, XA uses a two-phase commit (2PC) to ensure that all of a transaction's changes either take effect (''commit'') or do not (''roll back''), i.e., ''atomically''. Architecture Specifically, XA describes the interface between a global transaction manager and a specific application. An application that wants to use XA engages an XA transaction manager using a library or separate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Open Group
The Open Group is a global consortium that seeks to "enable the achievement of business objectives" by developing " open, vendor-neutral technology standards and certifications." It has 900+ member organizations and provides a number of services, including strategy, management, innovation and research, standards, certification, and test development. It was established in 1996 when X/Open merged with the Open Software Foundation. The Open Group is the certifying body for the UNIX trademark, and publishes the Single UNIX Specification technical standard, which extends the POSIX standards. The Open Group also develops and manages the TOGAF standard, which is an industry standard enterprise architecture framework. Members The 900+ members include a range of technology vendors and buyers as well as government agencies, including, for example, Capgemini, Fujitsu, Hewlett Packard Enterprise, Orbus Software, IBM, Huawei, the United States Department of Defense and NASA. There is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
