Transformation Patterns Al, Jean, Jeff, Kerry, Krzysztof, William, ??

Transformation Patterns What is a transformation pattern? common patterns I have seen structures

Examples MOF 1.3  EMF –more constructs in MOF than in EMF –want bi-directional (EMF  MOF 1.3) –e.g. MOF constraint into EMF annotation annotation had information on how to go back to EMF –Details a) Normal EMF  MOF is pretty easy b) But if the annotations have been changed, completing the round-trip is a serious problem –Only allow round-trip if it is consistent; otherwise (a)

More Examples UML to MOF –UML XMI transform to MOF XMI –example of a tool writing in ATL UML Activity to BPEL MOF to JMI CGI to EJB JavaDoc Genealogy data

More Examples… Cross-compilation –OQL to SQL –etc Databases –Normalizations –Logical to physical

Common pattern X Y A B C Z

Concrete Example: Database Logical  Physical Column Table Attribute Class

Characterizing Transformations as a whole 7) HOT (higher order transformation) 6) Ma  Mb (nothing) 5) Ma  Mb Exists MMa – MMp – MMb 4) Ma  Mb MMa “contains” MMb 3) Ma  Mb MMa “in” MMb 2) Ma  Mb MMa = MMb 1) Ma  Ma (within same model)

Vertical vs. Horizontal Transformations optimizations code expansion

Kinds of Transformation Property-Preserving –property P we have P(Ma) implies P(Mb) when Ma  Mb Evolution –platformMa:MMa  Ma’:MMa’ semantics-preserving: Meaning(Ma) = Meaning (Mb) –functional (change in requirements) Ma:MMa  Mb:MMa Compilation –generally semantics-preserving Optimization –one that is P-preserving, Q-reducing Refactoring –changing structure, semantics preserving –Its like also optimization (Q is “-ility” or “niceness” metric)

Source  Target Cardinality –all cases 1:1 1:M M:1 M:M Effect at type level –Does it increase or decrease number of types For case ?:M –Homogeneous –Heterogeneous

Explosion/Contraction State Explosion –Two states adding intermediate states into a transition Permutation –Elaborating all combinations of information –Version explosion multiple models coming in that are variants of each other Like Query languages –projection –selection –order –transitive closure

Philosophical Interlude What is different from Functional programming? –In functional programming main structure is a tree –In Model-driven approach main structure is a graph moving from trees to graphs gives more power –(but text can be better than pictures for some uses) All the meta-models are OO –Working with OO structures – graphs