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Optimistic Replication
Optimistic replication, also known as lazy replication, is a strategy for replication, in which replicas are allowed to diverge. Traditional pessimistic replication systems try to guarantee from the beginning that all of the replicas are identical to each other, as if there was only a single copy of the data all along. Optimistic replication does away with this in favor of eventual consistency, meaning that replicas are guaranteed to converge only when the system has been quiesced for a period of time. As a result, there is no longer a need to wait for all of the copies to be synchronized when updating data, which helps concurrency and parallelism. The trade-off is that different replicas may require explicit reconciliation later on, which might then prove difficult or even insoluble. Algorithms An optimistic replication algorithm consists of five elements: # Operation submission: Users submit operations at independent sites. # Propagation: Each site shares the operations it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symposium On Principles Of Distributed Computing
The Symposium on Principles of Distributed Computing (PODC) is an academic conference in the field of distributed computing organised annually by the Association for Computing Machinery (special interest groups SIGACT and SIGOPS). Scope and related conferences Work presented at PODC typically studies theoretical aspects of distributed computing, such as the design and analysis of distributed algorithms. The scope of PODC is similar to the scope of International Symposium on Distributed Computing (DISC), with the main difference being geographical: DISC is usually organized in European locations,DISC in . while PODC has been traditionally held in North America. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conflict-free Replicated Data Type
In distributed computing, a conflict-free replicated data type (CRDT) is a data structure that is replicated across multiple computers in a network, with the following features: # The application can update any replica independently, concurrently and without coordinating with other replicas. # An algorithm (itself part of the data type) automatically resolves any inconsistencies that might occur. # Although replicas may have different state at any particular point in time, they are guaranteed to eventually converge. The CRDT concept was formally defined in 2011 by Marc Shapiro, Nuno Preguiça, Carlos Baquero and Marek Zawirski. Development was initially motivated by collaborative text editing and mobile computing. CRDTs have also been used in online chat systems, online gambling, and in the SoundCloud audio distribution platform. The NoSQL distributed databases Redis, Riak and Cosmos DB have CRDT data types. Background Concurrent updates to multiple replicas of the same da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peer-to-peer Wiki
Wiki software (also known as a wiki engine or a wiki application), is collaborative software that runs a wiki, which allows the users to create and collaboratively edit pages or entries via a web browser. A wiki system is usually a web application that runs on one or more web servers. The content, including previous revisions, is usually stored in either a file system or a database. Wikis are a type of web content management system, and the most commonly supported off-the-shelf software that web hosting facilities offer. There are dozens of actively maintained wiki engines. They vary in the platforms they run on, the programming language they were developed in, whether they are open-source or proprietary, their support for natural language characters and conventions, and their assumptions about technical versus social control of editing. History The first generally recognized "wiki" application, WikiWikiWeb, was created by American computer programmer Ward Cunningham in 199 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Transformation
Operational transformation (OT) is a technology for supporting a range of collaboration functionalities in advanced collaborative software systems. OT was originally invented for consistency maintenance and concurrency control in collaborative editing of plain text documents. Its capabilities have been extended and its applications expanded to include group undo, locking, conflict resolution, operation notification and compression, group-awareness, HTML/XML and tree-structured document editing, collaborative office productivity tools, application-sharing, and collaborative computer-aided media design tools. In 2009 OT was adopted as a core technique behind the collaboration features in Apache Wave and Google Docs. History Operational Transformation was pioneered by C. Ellis and S. Gibbs in the GROVE (GRoup Outline Viewing Edit) system in 1989. Several years later, some correctness issues were identified and several approaches were independently proposed to solve these issues, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coda (file System)
Coda is a distributed file system developed as a research project at Carnegie Mellon University since 1987 under the direction of Mahadev Satyanarayanan. It descended directly from an older version of Andrew File System (AFS-2) and offers many similar features. The InterMezzo file system was inspired by Coda. Features Coda has many features that are desirable for network file systems, and several features not found elsewhere. # Disconnected operation for mobile computing. # Is freely available under the GPL # High performance through client-side persistent caching # Server replication # Security model for authentication, encryption and access control # Continued operation during partial network failures in server network # Network bandwidth adaptation # Good scalability # Well defined semantics of sharing, even in the presence of network failure Coda uses a local cache to provide access to server data when the network connection is lost. During normal operation, a user reads an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACM SIGMOD International Conference On Management Of Data
SIGMOD is the Association for Computing Machinery's Special Interest Group on Management of Data, which specializes in large-scale data management problems and databases. The annual ACM SIGMOD Conference, which began in 1975, is considered one of the most important in the field. While traditionally this conference had always been held within North America, it took place in Paris in 2004, Beijing in 2007, Athens in 2011, and Melbourne in 2015. The acceptance rate of the ACM SIGMOD Conference, averaged from 1996 to 2012, was 18%, and it was 17% in 2012. In association with SIGACT and SIGART, SIGMOD also sponsors the annual ACM Symposium on Principles of Database Systems (PODS) conference on the theoretical aspects of database systems. PODS began in 1982, and has been held jointly with the SIGMOD conference since 1991. Each year, the group gives out several awards to contributions to the field of data management. The most important of these is the SIGMOD Edgar F. Codd Innovations A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dennis Shasha
Dennis Elliot Shasha is an American professor of computer science at the Courant Institute of Mathematical Sciences, a division of New York University. He is also an associate director of NYU WIRELESS. His current areas of research include work done with biologists on pattern discovery for microarrays, combinatorial design, network inference, and protein docking; work done with physicists, musicians, and professionals in finance on algorithms for time series; and work on database applications in untrusted environments. Other areas of interest include database tuning as well as tree and graph matching. Background After graduating from Yale in 1977, he worked for IBM designing circuits and microcode for the IBM 3090. While at IBM, he earned his M.Sc. from Syracuse University in 1980. He completed his Ph.D. in applied mathematics at Harvard in 1984 (thesis advisor: Nat Goodman). Professor Shasha is a prolific author, researcher, tango dancer, climber, and public speaker. He ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patrick O'Neil
Patrick Eugene O'Neil (1942 – September 20, 2019) was an American computer scientist, an expert on databases, and a professor of computer science at the University of Massachusetts Boston.Curriculum vitae retrieved 2010-11-26. O'Neil did his undergraduate studies at the , receiving a B.S. in mathematics in 1963. After earning a master's degree at the , he moved to |
Jim Gray (computer Scientist)
James Nicholas Gray (1944 – declared dead in absentia 2012) was an American computer scientist who received the Turing Award in 1998 "for seminal contributions to database and transaction processing research and technical leadership in system implementation". Early years and personal life Gray was born in San Francisco, the second child of Ann Emma Sanbrailo, a teacher, and James Able Gray, who was in the U.S. Army; the family moved to Rome, Italy, where Gray spent most of the first three years of his life; he learned to speak Italian before English. The family then moved to Virginia, spending about four years there, until Gray's parents divorced, after which he returned to San Francisco with his mother. His father, an amateur inventor, patented a design for a ribbon cartridge for typewriters that earned him a substantial royalty stream. After being turned down for the Air Force Academy he entered the University of California, Berkeley as a freshman in 1961. To help pay for col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-master Replication
Multi-master replication is a method of database replication which allows data to be stored by a group of computers, and updated by any member of the group. All members are responsive to client data queries. The multi-master replication system is responsible for propagating the data modifications made by each member to the rest of the group and resolving any conflicts that might arise between concurrent changes made by different members. Multi-master replication can be contrasted with primary-replica replication, in which a single member of the group is designated as the "master" for a given piece of data and is the only node allowed to modify that data item. Other members wishing to modify the data item must first contact the master node. Allowing only a single master makes it easier to achieve consistency among the members of the group, but is less flexible than multi-master replication. Multi-master replication can also be contrasted with failover clustering where passive r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Usenet
Usenet () is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980.''From Usenet to CoWebs: interacting with social information spaces'', Christopher Lueg, Danyel Fisher, Springer (2003), , Users read and post messages (called ''articles'' or ''posts'', and collectively termed ''news'') to one or more topic categories, known as newsgroups. Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to the Internet forums that have become widely used. Discussions are threaded, as with web forums and BBSs, though posts are stored on the server sequentially.The jargon file v4.4.7 , Jargon File Archive. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
