| h2(#AdvancedMetamodelBindings). Creating Metamodel Bindings |
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| The Eclipse OCL component provides a generic specification of the OCL Abstract Syntax Model |
| plus bindings for two popular Eclipse metamodels: Ecore and UML. Users of the OCL API |
| can likewise create bindings for their metamodels, to integrate OCL with their modeling |
| languages. |
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| The "@Environment@":http://download.eclipse.org/ocl/javadoc/4.1.0/org/eclipse/ocl/Environment.html interface has a generic type signature with several parameters, representing the metamodeling |
| constructs required by OCL, that it borrows from UML, EMOF, and the other metamodels that |
| it targets. The Javadoc for that interface defines the mappings, and the same type parameter |
| names are used consistently throughout the OCL API. |
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| !{width:70%}images/5180-bindings.png(Metamodel Bindings API)! |
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| To provide a metamodel binding, a client must provide implementations of the following interfaces: |
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| * @Environment@ and @EnvironmentFactory@, supplying suitable substitutions for the generic type parameters. Note that not all of these are actually required; for example, Ecore does not have the concept of @State@, so it just substitutes @EObject@ |
| * @EvaluationEnvironment@ for accessing properties of run-time instances of models |
| * @UMLReflection@ for introspecting models (instances of thetarget metamodel) |
| * @OCLStandardLibrary@, providing the instances of the metamodel's @Classifier@ metaclass that implement the OCL Standard Library types |
| * @OCLFactory@, providing a factory for all of the metaclasses of the Abstract Syntax Model |
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| This last item, above, necessitates furthermore that the metamodel binding provide a |
| concrete specialization of the Abstract Syntax Model (in its entirety) that mixes in the |
| target metamodel's correspondents of the UML @Classifier@ and |
| @TypedElement@ metaclasses. The former is required to provide |
| compatibility of the metaclasses in the OCL @Types@ with the |
| target metamodel's type system. The latter is required for compatibility of the metaclasses |
| in the OCL @Expressions@ package with the target metamodel's |
| typed elements. |
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| h3. The OCL Abstract Syntax Model |
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| The following diagram summarizes the metaclasses of the OCL @Types@ package: |
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| !{width:70%}images/5180-ocltypes.png(OCL Types Package)! |
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| The following diagram summarizes the call expression metaclasses of the OCL @Expressions@ package: |
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| !{width:70%}images/5180-callexp.png(OCL Expressions Package)! |
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| The following diagram summarizes the literal expression metaclasses of the OCL @Expressions@ package: |
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| !{width:40%}images/5180-literalexp.png(OCL Expressions Package - the Literal Expressions)! |
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| The following diagram summarizes the remaining metaclasses of the OCL @Expressions@ package: |
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| !{width:50%}images/5180-miscexp.png(OCL Expressions Package - the Remainder)! |
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