Object model In computing, object model has two related but distinct meanings: An object model consists of the following important features: Object Reference Objects can be accessed via object references. Interfaces An interface provides a definition of the signature of a set of methods without specifying their implementation. Actions An action in object-oriented programming (OOP) is initiated by an object invoking a method in another object. Exceptions Programs can encounter various errors and unexpected conditions of varying seriousness. See also Literature Weisfeld, Matt (2003). External links Data (computing) Data (/ˈdeɪtə/ DAY-tə, /ˈdætə/ DA-tə, or /ˈdɑːtə/ DAH-tə; treated as singular, plural, or as a mass noun) is any sequence of one (1) or more symbols given meaning by specific act(s) of interpretation. Data is not information. Data requires interpretation to become information. To translate data to information, there must be several known factors considered. The factors involved are determined by the creator of the data and the desired information. Digital data is data that is represented using the binary number system of ones (1) and zeros (0). In an alternate usage, binary files (which are not human-readable) are sometimes called "data" as distinguished from human-readable "text". The total amount of digital data in 2007 was estimated to be 281 billion gigabytes (= 281 exabytes). At its most essential, a single datum is a value stored at a specific location. To store data bytes in a file, they have to be serialized in a "file format".
What is Database (DB)? Webopedia Main » TERM » D » By Vangie Beal (1) Often abbreviated DB, a database is basically a collection of information organized in such a way that a computer program can quickly select desired pieces of data. Traditional databases are organized by fields, records, and files. An alternative concept in database design is known as Hypertext. To access information from a database, you need a database management system (DBMS). (2) Increasingly, the term database is used as shorthand for database management system. DBMS definition of DBMS in the Free Online Encyclopedia. System for quick search and retrieval of information from a database. The DBMS determines how data are stored and retrieved. It must address problems such as security, accuracy, consistency among different records, response time, and memory requirements. These issues are most significant for database systems on computer networks. For more information on database management system (DBMS), visit Britannica.com. (DataBase Management System) Software that controls the organization, storage, retrieval, security and integrity of data in a database. DBMSs may work with traditional programming languages (COBOL, C, etc.) or they may include their own programming language for application development. DBMSs let information systems be changed more easily as the organization's requirements change. Major Features of a DBMS Data Security The DBMS can prevent unauthorized users from viewing or updating the database. This is a common misconception about using a desktop computer DBMS. Database Design
Database tuning Database tuning describes a group of activities used to optimize and homogenize the performance of a database. It usually overlaps with query tuning, but refers to design of the database files, selection of the database management system (DBMS) application, and configuration of the database's environment (operating system, CPU, etc.). Database tuning aims to maximize use of system resources to perform work as efficiently and rapidly as possible. I/O tuning Hardware and software configuration of disk subsystems are examined: RAID levels and configuration, block and stripe size allocation, and the configuration of disks, controller cards, storage cabinets, and external storage systems such as SANs. DBMS tuning DBMS tuning refers to tuning of the DBMS and the configuration of the memory and processing resources of the computer running the DBMS. Memory is allocated for data, execution plans, procedure cache, and work space[clarify]. Database maintenance References
Message Passing Interface History The message passing interface effort began in the summer of 1991 when a small group of researchers started discussions at a mountain retreat in Austria. Out of that discussion came a Workshop on Standards for Message Passing in a Distributed Memory Environment held on April 29–30, 1992 in Williamsburg, Virginia. At this workshop the basic features essential to a standard message-passing interface were discussed, and a working group established to continue the standardization process. Jack Dongarra, Rolf Hempel, Tony Hey, and David W. The MPI effort involved about 80 people from 40 organizations, mainly in the United States and Europe. The MPI standard defines the syntax and semantics of a core of library routines useful to a wide range of users writing portable message passing programs in Fortran and C. MPI provides parallel hardware vendors with a clearly defined base set of routines that can be efficiently implemented. Overview Functionality Concepts
5 of the Best Relational Database Management System for Linux A Database Management System (DBMS) is described as a set of computer programs that manages the creation, maintenance, and administration of a database. It is a system software package that supports the use of unified collection of data records and files known as databases. A DBMS could utilize any of a variety of database models, such as the network model or relational model. A relational database management system (RDBMS) is a DBMS in which data is stored in the form of tables, and the relationship among the data is stored in the form of tables as well. For those of you who are interested, I have here a list of some of the best Relational Database Management System (RDBMS) for Linux (in no particular order): MySQL MySQL is a central component of the widely used LAMP (Linux, Apache, MySQL, Perl/PHP/Python) web application software stack. Apache Derby Apache Derby is an open source relational database management system (RDBMS) that is based on Java, JDBC, and SQL standards. PostgreSQL
Critère de succès : la taille de l'équipe Il y a eu de nombreuses études sur la performance des équipes en fonction de leur taille. La conclusion générale est que la taille optimale d'une équipe se situe à peu près entre sept et onze personnes. Il s'agit d'un juste équilibre, entre d'une part une équipe avec trop peu de personnes pour assurer la diversité et l'expertise et, d'autre part trop de personnes pour obtenir une pleine participation et une communication ouverte.Lorsque les équipes deviennent trop grandes, il leur est très difficile de parvenir à une compréhension commune d'un problème ou d'une situation. Le niveau de performance d'une équipe est très sensible aux relations individuelles entre les membres de l'équipe.
Computer cluster A computer cluster consists of a set of loosely or tightly connected computers that work together so that, in many respects, they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software.[better source needed] The components of a cluster are usually connected to each other through fast local area networks ("LAN"), with each node (computer used as a server) running its own instance of an operating system. In most circumstances, all of the nodes use the same hardware and the same operating system, although in some setups (i.e. using Open Source Cluster Application Resources (OSCAR)), different operating systems can be used on each computer, and/or different hardware. They are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability. History