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Service Abstraction
Service abstraction is a design principle that is applied within the service-orientation design paradigm so that the information published in a service contract is limited to what is required to effectively utilize the service The service contract should not contain any superfluous information that is not required for its invocation. Also that the information should be limited to the serviced contract (technical contract and the service level agreement) only, no other document or medium should be made available to the service consumers other than the service contract that contains additional service related information. Purpose A service contract that contains details about what it encapsulates (e.g., the logic, implementation and the technology used to build the service) may end up being used in a particular manner by providing the service consumer more knowledge about the working of the service. In the case of service-orientation, more knowledge is not necessarily better. There is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Service-orientation
Service-orientation is a design paradigm for computer software in the form of services. The principles of service-oriented design stress the separation of concerns in the software. Applying service-orientation results in units of software partitioned into discrete, autonomous, and network-accessible units, each designed to solve an individual concern. These units qualify as services. History of service-orientation principles and tenets Service-orientation has received a lot of attention since 2003 due to the benefits it promises. These include increased return on investment, organisational agility and interoperability as well as a better alignment between business and IT. It builds heavily on earlier design paradigms and enhances them with standardisation, loose coupling and business involvement. The paradigm lost momentum in 2009; since 2014, renewed interest can be observed under the Microservices moniker. In technology, different vendor SOA platforms have used different definit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Class
In programming languages, an abstract type is a type in a nominative type system that cannot be instantiated directly; a type that is not abstract – which ''can'' be instantiated – is called a ''concrete type''. Every instance of an abstract type is an instance of some concrete subtype. Abstract types are also known as ''existential types''. An abstract type may provide no implementation, or an incomplete implementation. In some languages, abstract types with no implementation (rather than an incomplete implementation) are known as ''protocols'', ''interfaces'', ''signatures'', or ''class types''. In class-based object-oriented programming, abstract types are implemented as ''abstract classes'' (also known as ''abstract base classes''), and concrete types as ''concrete classes''. In generic programming, the analogous notion is a concept, which similarly specifies syntax and semantics, but does not require a subtype relationship: two unrelated types may satisfy the same conce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Design Patterns
''Design Patterns: Elements of Reusable Object-Oriented Software'' (1994) is a software engineering book describing software design patterns. The book was written by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, with a foreword by Grady Booch. The book is divided into two parts, with the first two chapters exploring the capabilities and pitfalls of object-oriented programming, and the remaining chapters describing 23 classic software design patterns. The book includes examples in C++ and Smalltalk. It has been influential to the field of software engineering and is regarded as an important source for object-oriented design theory and practice. More than 500,000 copies have been sold in English and in 13 other languages. The authors are often referred to as the Gang of Four (GoF). History The book started at a birds of a feather (BoF) session at OOPSLA '90, "Towards an Architecture Handbook", run by Bruce Anderson, where Erich Gamma and Richard Helm met and d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Hacking
A hacker is a person skilled in information technology who uses their technical knowledge to achieve a goal or overcome an obstacle, within a computerized system by non-standard means. Though the term ''hacker'' has become associated in popular culture with a ''security hacker''someone who utilizes their technical know-how of bugs or exploits to break into computer systems and access data which would otherwise be inaccessible to them – hacking can also be utilized by legitimate figures in legal situations. For example, law enforcement agencies sometimes use hacking techniques in order to collect evidence on criminals and other malicious actors. This could include using anonymity tools (such as a VPN, or the dark web) to mask their identities online, posing as criminals themselves. Likewise, covert world agencies can employ hacking techniques in the legal conduct of their work. On the other hand, hacking and cyber-attacks are used extra- and illegally by law enforcement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database
In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases spans formal techniques and practical considerations, including data modeling, efficient data representation and storage, query languages, security and privacy of sensitive data, and distributed computing issues, including supporting concurrent access and fault tolerance. A database management system (DBMS) is the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS software 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 appli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Service Discoverability Principle
Discoverability is the degree to which something, especially a piece of content or information, can be found in a search of a file, database, or other information system. Discoverability is a concern in library and information science, many aspects of digital media, software and web development, and in marketing, since products and services cannot be used if people cannot find it or do not understand what it can be used for. Metadata, or "information about information," such as a book's title, a product's description, or a website's keywords, affects how discoverable something is on a database or online. Adding metadata to a product that is available online can make it easier for end users to find the product. For example, if a song file is made available online, making the title, name of the band, genre, year of release, and other pertinent information available in connection with this song means the file can be retrieved more easily. Organizing information by putting it into alpha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quality Of Service
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc. In the field of computer networking and other packet-switched telecommunication networks, quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priorities to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. Quality of service is particularly important for the transport of traffic with special requirements. In particular, developers have introduced Voice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Service Refactoring
Within the service-orientation design paradigm, Service Refactoring is a design pattern, which is applied to an existing service so that either the service logic or its implementation can be changed without affecting the service consumers. Rationale It is natural for a service to undergo changes for various reasons. The change could be required because the underlying implementation e.g. databases, legacy systems, etc. needs to be upgraded or simply because the original service logic was not making efficient use of memory. In other cases, the change could be initiated by the service consumers themselves. For example, with limited concurrent usage, the service performs as stated in its SLA, however, with an increase in its concurrent usage, the service is unable to fulfill its SLA, consequently the service needs to respond to the increasing performance demands from its service consumers.Jason BloomberThe Four Pillars of Service-Oriented Development nline Date accessed: 27 April 2010 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Program
A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program in its human-readable form is called source code. Source code needs another computer program to execute because computers can only execute their native machine instructions. Therefore, source code may be translated to machine instructions using the language's compiler. (Assembly language programs are translated using an assembler.) The resulting file is called an executable. Alternatively, source code may execute within the language's interpreter. If the executable is requested for execution, then the operating system loads it into memory and starts a process. The central processing unit will soon switch to this process so it can fetch, decode, and then execute each machine instruction. If the source code is requested for execution, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Design Paradigm
A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design'' expresses the process of developing a design. In some cases, the direct construction of an object without an explicit prior plan (such as in craftwork, some engineering, coding, and graphic design) may also be considered to be a design activity. The design usually has to satisfy certain goals and constraints; may take into account aesthetic, functional, economic, or socio-political considerations; and is expected to interact with a certain environment. Typical examples of designs include architectural and engineering drawings, circuit diagrams, sewing patterns and less tangible artefacts such as business process models. Designing People who produce designs are called ''designers''. The term 'designer' generally refers to someone who wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information Hiding
In computer science, information hiding is the principle of segregation of the ''design decisions'' in a computer program that are most likely to change, thus protecting other parts of the program from extensive modification if the design decision is changed. The protection involves providing a stable interface which protects the remainder of the program from the implementation (whose details are likely to change). Written in another way, information hiding is the ability to prevent certain aspects of a class or software component from being accessible to its clients, using either programming language features (like private variables) or an explicit exporting policy. Overview The term ''encapsulation'' is often used interchangeably with information hiding. Not all agree on the distinctions between the two, though; one may think of information hiding as being the principle and encapsulation being the technique. A software module hides information by encapsulating the information ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dependency (computer Science)
In software engineering, coupling is the degree of interdependence between software modules; a measure of how closely connected two routines or modules are; the strength of the relationships between modules. Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa. Low coupling is often thought to be a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability. History The software quality metrics of coupling and cohesion were invented by Larry Constantine in the late 1960s as part of a structured design, based on characteristics of “good” programming practices that reduced maintenance and modification costs. Structured design, including cohesion and coupling, were published in the article ''Stevens, Myers & Constantine'' (1974) and the book ''Yourdon & Constantine'' (1979), and the latter subsequently became sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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