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Co- and Contra-Variance

Interoperability using contra-variance [26] for components in general is existent, if for all provided interfaces of a component (B)

Vice versa for all required interfaces of A it has to be true that

If all provided and required interfaces of a component satisfy the conditions above, component interoperability is given.

Conditions for interoperability are not formulated by the PCM itself, but they are underlying assumptions on the characteristics of components and interfaces. The evaluation of interoperability constraints is not seen as a part of the model structure of the PCM, as concrete constraints for interoperability might be strategy-dependant. According with the ideas of the strategy pattern ([24][p. 315]) functions and the model itself (as a data container) are separated.


next up previous contents index
Next: Conforms-Relation Up: Interoperability Previous: Interoperability   Contents   Index
Snowball 2007-03-16