Software component

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Modular unit of software

title: "Software component" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["software-architecture", "software-development", "software-engineering"] description: "Modular unit of software" topic_path: "technology/software-engineering" source: "https://en.wikipedia.org/wiki/Software_component" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Modular unit of software ::

A software component is a modular unit of software that encapsulates specific functionality. The desired characteristics of a component are reusability and maintainability.

Value

Components allow software developers to assemble software with reliable parts rather than writing code for every aspect. It makes implementation more like factory assembly than custom building.

Attributes

Desirable attributes of a component include but are not limited to:

Cohesive encapsulates related functionality
Reusable
Robust
Substitutable can be replaced by another component with the same interface
Documented
Tested

Third-party

Some components are built in-house by the same organization or team building the software system. Some are third-party, developed elsewhere and assembled into the software system.

Component-based software engineering

For large-scale systems, component-based development encourages a disciplined process to manage complexity.

Framework

Some components conform to a framework technology that allows them to be consumed in a well-known way. Examples include: CORBA, COM, Enterprise JavaBeans, and the .NET Framework.

Modeling

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/83/Component-based-Software-Engineering-example2.png" caption="UML"] ::

Component design is often modeled visually. In Unified Modeling Language (UML) 2.0 a component is shown as a rectangle, and an interface is shown as a lollipop to indicate a provided interface and as a socket to indicate consumption of an interface.

History

The idea of reusable software components was promoted by Douglas McIlroy in his presentation at the NATO Software Engineering Conference of 1968. (One goal of that conference was to resolve the so-called software crisis of the time.) In the 1970s, McIlroy put this idea into practice with the addition of the pipeline feature to the Unix operating system.

Brad Cox refined the concept of a software component in the 1980s.{{cite web | access-date = 2011-07-29 | author = Rainer Niekamp | page = 4 | publisher = Gestión de Congresos - CIMNE/Institute for Scientific Computing, TU Braunschweig | title = Software Component Architecture | quote = The modern concept of a software component largely defined by Brad Cox of Stepstone, = Objective-C programming language | url = http://congress.cimne.upc.es/cfsi/frontal/doc/ppt/11.pdf | archive-date = 2012-03-28 | archive-url = https://web.archive.org/web/20120328081234/http://congress.cimne.upc.es/cfsi/frontal/doc/ppt/11.pdf | url-status = dead

IBM introduced System Object Model (SOM) in the early 1990s.{{cite web | access-date = 2011-07-29 | author = Raphael Gfeller | date = December 9, 2008 | page = 4 | publisher = HSR - Hochschule für Technik Rapperswill | title = Upgrading of component-based application | quote = 1990, IBM invents their System Object Model. 1990, as a reaction, Microsoft released OLE 1.0 OLE custom controls (OCX) | url = http://wiki.ita.hsr.ch/SemProgAnTr/files/Automated_upgrading_of_component.Präsentation.pptx

Microsoft introduced Component Object Model (COM) in the early 1990s. Microsoft built many domain-specific component technologies on COM, including Distributed Component Object Model (DCOM), Object Linking and Embedding (OLE), and ActiveX.

References

(11 July 2023). "Tutorial notes: Software Components and Connectors".
(16 April 2024). "Types of Software Components — With Examples".
[[Douglas C. Schmidt]]. "Why Software Reuse has Failed and How to Make It Work for You".
(2011). "A Classification Framework for Software Component Models". IEEE Transactions on Software Engineering.
(2007). "Software Component Models". IEEE Transactions on Software Engineering.
McIlroy, Malcolm Douglas. (January 1969). "Mass produced software components". Scientific Affairs Division, NATO.
[[Brad Cox]]. (1991). "Object Oriented Programming: An Evolutionary Approach". Addison Wesley.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::