Model transformation: Difference between revisions

Revision as of 13:27, 12 December 2016

Revision as of 04:02, 7 January 2017

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A unidirectional model transformation has only one mode of execution: that is, it always takes the same type of input and produces the same type of output. Unidirectional model transformations are useful in compilation-like situations, where any output model is read-only. The relevant notion of consistency is then very simple: the input model is consistent with the model that the transformation would produce as output, only.

For a bidirectional model transformation, the same type of model can sometimes be input and other times be output. [[Bidirectional transformationstransformation]]s are necessary in situations where people are working on more than one model and the models must be kept consistent. Then a change to either model might necessitate a change to the other, in order to maintain consistency between the models. Because each model can incorporate information which is not reflected in the other, there may be many models which are consistent with a given model. Important special cases are:

*bijective transformations, in which there is exactly one model which is consistent with any given model; that is, the consistency relation is bijective. A pair of models is consistent if and only if it is related by the consistency bijection. Both models contain the same information, but presented differently.