A component in the

Unified Modeling Language The Unified Modeling Language (UML) is a general-purpose, developmental modeling language in the field of software engineering that is intended to provide a standard way to visualize the design of a system. The creation of UML was originally m ...

represents a

modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...

part of a

system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and express ...

that encapsulates the

state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...

and

behavior Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as we ...

of a number of classifiers. Its behavior is defined in terms of ''provided'' and ''required''

interfaces Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...

,OMG (2008).
OMG Unified Modeling Language (OMG UML), Superstructure, V2.1.2
' is self-contained, and substitutable. A number of UML standard stereotypes exist that apply to components. A component has an external and internal view, also known as "

black-box In science, computing, and engineering, a black box is a system which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). The te ...

" and "white-box", respectively. In its external view, there are public properties and operations. For its internal view, there are private properties and realizing classifiers and shows how external behavior is realized internally. A component may be replaced at design time or run-time by another if and only if their provided and required interfaces are identical. This idea is the underpinning for the

plug-and-play In computing, a plug and play (PnP) device or computer bus is one with a specification that facilitates the recognition of a hardware component in a system without the need for physical device configuration or user intervention in resolving resou ...

capability of component-based systems and promotes

software reuse In software development (and computer programming in general), code reuse, also called software reuse, is the use of existing software, or software knowledge, to build new software, following the reusability principles. Code reuse may be achiev ...

. Larger pieces of a

's functionality may be assembled by reusing components as parts in an encompassing component or assembly of components, and wiring together their required and provided interfaces. A component acts like a package for all model elements that are involved in or related to its definition, which should be either owned or imported explicitly. Typically the classifiers related to a component are owned by it. Components of a system are modeled by means of

component diagram In Unified Modeling Language (UML), a component diagram depicts how components are wired together to form larger components or software systems. They are used to illustrate the structure of arbitrarily complex systems. Overview A component diag ...

s throughout the development life cycle and successively refined into deployment and run-time. In diagrams, components are shown as a

rectangle In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°); or a parallelogram contain ...

with the keyword «component». Optionally, in the right hand corner a component icon can be displayed. This is a rectangle with two smaller rectangles protruding from its left hand side. If the icon symbol is shown, the keyword «component» may be hidden as seen to the side.

References

External links

Component in UML2

Unified Modeling Language {{uml-stub

See also

References

External links