10 maart 2000SEESCOA Components Programming Technology Lab (PROG) System & Software Engineering Lab (SSEL) Dept. of Computer Sciences (DINF) Vrije Universiteit Brussel (VUB) Werner Van Belle (WVB) Tom Toutenel (TT)

2 10 maart 2000SEESCOA Components & Industrial Partners “A nontrivial piece of software, that fulfills a clear function, has a clear boundary and can be integrated in a well-defined architecture. The component can, but need not be reusable.” Alcatel CDD “A unit of packaging that includes an implementation, a specification of interfaces provided and required, validation code, and the design (incl. documents and source).” Alcatel RCD

3 10 maart 2000SEESCOA Components & Industrial Partners (ctd) “Has an API that describes behaviour, not implementation.” Agfa (Portex presentation). “Clear interface. Self supporting, independent from other components. Component is a collection of routines, classes.” Barco Graphics. “Obeys to the rules of its Component System.” Laszlo Huray.

4 10 maart 2000SEESCOA A Software Component Definition “A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third parties” Szyperski & Pfister, ECOOP 1996

5 10 maart 2000SEESCOA A Component Independent entity  own code/data space  own control flow Has an interface (API)  provided/required interface  describes expected interaction Documented semantics Quality of Service  Memory, Resources Needs a component system Validation code Documented design & source

6 10 maart 2000SEESCOA A Component System Handles the interaction between components  allows specification of real-time behaviour Support for asynchronous/synchronous events Ensures interfaces are used correctly (as specified by the interacting components) Provides glue components to connect ‘different’ components  allows for example grouping of components Platform transparency (seen from the components)