|
Layer (object-oriented Design)
In software object-oriented design, a layer is a group of classes that have the same set of link-time module dependencies to other modules. In other words, a layer is a group of reusable components that are reusable in similar circumstances. In programming languages, the layer distinction is often expressed as "import" dependencies between software modules. Layers are often arranged in a tree-form hierarchy, with dependency relationships as links between the layers. Dependency relationships between layers are often either inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Offi ..., composition or aggregation relationships, but other kinds of dependencies can also be used. Layers is an architectural pattern described in many books, for example ''Pattern-Oriented Software ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software
Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures. Software in a programming language is run through a compiler or Interpreter (computing), interpreter to execution (computing), execute on the architecture's hardware. Over time, software has become complex, owing to developments in Computer network, networking, operating systems, and databases. Software can generally be categorized into two main types: # operating systems, which manage hardware resources and provide services for applicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inheritance (object-oriented Programming)
In object-oriented programming, inheritance is the mechanism of basing an Object (computer science), object or Class (computer programming), class upon another object (Prototype-based programming, prototype-based inheritance) or class (Class-based programming, class-based inheritance), retaining similar implementation. Also defined as deriving new classes (#Subclasses and superclasses, sub classes) from existing ones such as super class or Fragile base class, base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages like C++, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object", with the exception of: Constructor (object-oriented programming), constructors, destructors, operator overloading, overloaded operators and friend functions of the base class. Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shearing Layers
Shearing layers is a concept coined by architect Frank Duffy, which was later elaborated by Stewart Brand in his book, '' How Buildings Learn: What Happens After They're Built'' (Brand, 1994), and refers to buildings as composed of several layers of change. The concept has been adopted by a number of technology vendors to also describe the different layers of systems within an organisation. Description The shearing layers concept views buildings as a set of components that evolve in different timescales; Frank Duffy summarized this view in his phrase: "Our basic argument is that there isn't any such thing as a building. A building properly conceived is several layers of longevity of built components" (quoted in (Brand, 1994)). The work of Duffy and DEGW identified four shearing layers (Duffy, 1992): * Shell – the traditional structure of the building that might last for 30–50 years. * Services – cabling, plumbing, aircon that needs replacing every 15 years. * Scenery – la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multitier Architecture
In software engineering, multitier architecture (often referred to as ''n''-tier architecture) is a client–server architecture in which presentation, application processing and data management functions are physically separated. The most widespread use of multitier architecture is the three-tier architecture (for example, Cisco's Hierarchical internetworking model). ''N''-tier application architecture provides a model by which developers can create flexible and reusable applications. By segregating an application into tiers, developers acquire the option of modifying or adding a specific tier, instead of reworking the entire application. N-tier architecture is a good fit for small and simple applications because of its simplicity and low-cost. Also, it can be a good starting point when architectural requirements are not clear yet. A three-tier architecture is typically composed of a ''presentation'' tier, a ''logic'' tier, and a ''data'' tier. While the concepts of layer an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstraction Layer
In computing, an abstraction layer or abstraction level is a way of hiding the working details of a subsystem. Examples of software models that use layers of abstraction include the OSI model for network protocols, OpenGL, and other graphics libraries, which allow the separation of concerns to facilitate interoperability and platform independence. In computer science, an abstraction layer is a generalization of a Conceptual model (computer science), conceptual model or algorithm, away from any specific implementation. These generalizations arise from broad similarities that are best encapsulated by models that express similarities present in various specific implementations. The simplification provided by a good abstraction layer allows for easy reuse by distilling a useful concept or design pattern so that situations, where it may be accurately applied, can be quickly recognized. Just composing lower-level elements into a construct doesn't count as an abstraction layer unless it s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Architectural Pattern (computer Science)
Software architecture pattern is a reusable, proven solution to a specific, recurring problem focused on architectural design challenges, which can be applied within various architectural styles. Examples Some examples of architectural patterns: * Publish–subscribe pattern * Message broker See also * List of software architecture styles and patterns * Process Driven Messaging Service * Enterprise architecture Enterprise architecture (EA) is a business function concerned with the structures and behaviours of a business, especially business roles and processes that create and use business data. The international definition according to the Federation of ... * Common layers in an information system logical architecture References Bibliography * * * {{Design Patterns patterns Software design patterns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Composition
In computer science, object composition and object aggregation are closely related ways to combine objects or data types into more complex ones. In conversation, the distinction between composition and aggregation is often ignored. Common kinds of compositions are objects used in object-oriented programming, tagged unions, sets, sequences, and various graph structures. Object compositions relate to, but are not the same as, data structures. Object composition refers to the logical or conceptual structure of the information, not the implementation or physical data structure used to represent it. For example, a sequence differs from a set because (among other things) the order of the composed items matters for the former but not the latter. Data structures such as arrays, linked lists, hash tables, and many others can be used to implement either of them. Perhaps confusingly, some of the same terms are used for both data structures and composites. For example, "binary tree" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hierarchy
A hierarchy (from Ancient Greek, Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that are represented as being "above", "below", or "at the same level as" one another. Hierarchy is an important concept in a wide variety of fields, such as architecture, philosophy, design, mathematics, computer science, organizational theory, systems theory, systematic biology, and the social sciences (especially political science). A hierarchy can link entities either directly or indirectly, and either vertically or diagonally. The only direct links in a hierarchy, insofar as they are hierarchical, are to one's immediate superior or to one of one's subordinates, although a system that is largely hierarchical can also incorporate alternative hierarchies. Hierarchical links can extend "vertically" upwards or downwards via multiple links in the same direction, following a path (graph theory), path. All parts of the hierarchy that are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-oriented Design
Object-oriented analysis and design (OOAD) is a technical approach for analyzing and designing an application, system, or business by applying object-oriented programming, as well as using visual modeling throughout the software development process to guide stakeholder communication and product quality. OOAD in modern software engineering is typically conducted in an iterative and incremental way. The outputs of OOAD activities are analysis models (for OOA) and design models (for OOD) respectively. The intention is for these to be continuously refined and evolved, driven by key factors like risks and business value. History In the early days of object-oriented technology before the mid-1990s, there were many different competing methodologies for software development and object-oriented modeling, often tied to specific Computer Aided Software Engineering (CASE) tool vendors. No standard notations, consistent terms and process guides were the major concerns at the time, which ... [...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] |
Reusability
In computer programming, reusability describes the quality of a software asset that affects its ability to be used in a software system for which it was ''not'' specifically designed. An asset that is easy to reuse and provides utility is considered to have high reusability. A related concept, leverage involves modifying an existing asset to meet system requirements. The ability to reuse can be viewed as the ability to build larger things from smaller parts, and to identify commonality among the parts. Reusability is often a required characteristic of platform software. Reusability brings several aspects to software development that do not need to be considered when reusability is not required. Reusability may be impacted by various DevOps aspects including: build, packaging, distribution, installation, configuration, deployment, maintenance and upgrade. If these aspects are not considered, software may seem to be reusable based on its design, but may not be reusable in p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
