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7.2 Defi nitionen für So ware-Komponenten
Im Folgenden werden einige Aussagen, Charakterisierungen oder Defi nitionen aus der
Literatur zum Begriff Komponente im So ware-Umfeld aufgeführt. Die Liste ist chronolo-
gisch geordnet. Den ersten Text der Liste von McIlroy gebe ich hier wieder, um zu zeigen,
dass die Idee von So ware-Komponenten bereits in den 60er Jahren des 20. Jahrhunderts
in den Köpfen der Leute vorhanden war, wobei damals die Vorstellung einer Industrie
für die Produktion von Komponenten und deren Wiederverwendbarkeit im Vordergrund
stand:
! McIlroy, 1969: My thesis is that the so ware industry is weakly founded, and that one
aspect of this weakness is the absence of a so ware components subindustry. . . . I suspect
that the very name “so ware components” has probably already conjured up for you an
idea of how the industry could operate.
! Booch, 1987: A reusable so ware component is a logically cohesive, loosely coupled
module that denotes a single abstraction.
! Nierstrasz and Dami, 1995: A component is a static abstraction with plugs. By “static”,
we mean that a so ware component is a long-lived entity that can be stored in a so -
ware base. By “abstraction”, we mean that a component puts a more or less opaque
boundary around the so ware it encapsulates. “With plugs” means that there are well-
defi ned ways to interact and communicate with the component (parameters, ports, mes-
sages, etc.). So ware composition, then, is the process of constructing applications by
interconnecting so ware components through their plugs. The nature of the plugs, the
binding mechanisms and the compatibility rules for connecting components can vary
quite a bit.
! European Conference on Object-Oriented Programming, 1996: A so ware component is a
unit of composition with contractually specifi ed interfaces and explicit context dependen-
cies only. A so ware component can be deployed independently and is subject to compo-
sition by third parties.
! Nierstrasz und Lumpe, 1997: Eine So warekomponente ist Teil eines Komponenten-
Frameworks, das (i) eine Bibliothek von Black-Box-Komponenten zu Verfügung stellt, (ii)
eine wiederverwendbare So ware-Architektur defi niert, in der die Komponenten geeig-
net integriert sind, und (iii) eine bestimmte Art von Glue, die es uns erlaubt, Komponen-
ten miteinander zu verbinden.
! Szyperski, 1997: So ware components are binary units of independent production, acqui-
sition, and deployment that interact to form a functioning system.
! D'Souza und Wills, 1998: A so ware component is a coherent package of so ware imple-
mentations that (a) has explicit and well-specifi ed interfaces for services it provides; (b)
has explicit and well-specfi ed interfaces for services it expects; and (c) can be composed
with other components, perhaps customizing some of their properties, without modifying
the components themselves.
! Councill/Heineman, 2001: A so ware element that conforms to a component model and
can be independently deployed and composed without modifi cation according to a compo-
sition standard.
 
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