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| Extensions to the Ecore metamodel for UML-specific concepts supported by the |
| OCL language. |
| |
| <h2>Package Specification</h2> |
| <p> |
| This package extends the Ecore metamodel to support UML concepts required by |
| the OCL language that Ecore does not implement. These extensions are not |
| required for the use of OCL on Ecore models, but would be necessary for other |
| metamodels that support some of these UML concepts. For example, a metamodel |
| describing SQL might map the intersection table of a many-to-many relationship |
| as an {@link org.eclipse.emf.ocl.uml.AssociationClass} rather than a |
| many-to-many {@link org.eclipse.emf.ecore.EReference}, especially as it may |
| have additional columns (attributes) of its own. |
| </p> |
| <p> |
| The following Ecore extensions are defined: |
| </p> |
| <ul> |
| <li>{@link org.eclipse.emf.ocl.uml.Operation}: extends the |
| {@link org.eclipse.emf.ecore.EOperation} metaclass to add the |
| <code>query</code> boolean attribute. OCL constraints may be defined |
| on any kind of operation, but may only invoke query operations (that are |
| therefore guaranteed not to modify the system state). This metaclass is |
| useful to indicate which <code>EOperation</code>s are (not) queries.</li> |
| <li>{@link org.eclipse.emf.ocl.uml.Signal}: extends the |
| {@link org.eclipse.emf.ecore.EClass} metaclass to indicate that a type |
| corresponds to a UML Signal. Only <code>Signal</code>s can be sent |
| by OCL messages.</li> |
| <li>{@link org.eclipse.emf.ocl.uml.AssociationEnd}: extends the |
| {@link org.eclipse.emf.ecore.EReference} metaclass represent a navigable |
| end of a UML association. This is most useful for association ends that |
| have qualifiers, represented by {@link org.eclipse.emf.ocl.uml.Qualifier}s. |
| For other associations, the <code>EReference</code> metaclass is sufficient |
| to model the ends. <code>Qualifier</code>s have type, multiplicity, |
| and ordering/uniqueness as do other |
| {@link org.eclipse.emf.ecore.ETypedElement}s.</li> |
| <li>{@link org.eclipse.emf.ocl.uml.AssociationClassEnd}: extends the |
| {@link org.eclipse.emf.ecore.EReference} metaclass represent a navigable |
| end of a UML association class (rather than just an association). |
| The <code>AssociationClassEnd</code> references the |
| {@link org.eclipse.emf.ecore.EClass} representing the association class, which |
| is used to resolve the navigation to association classes (navigation being |
| implied by the source's navigable association class ends).</li> |
| </ul> |
| <p> |
| The other types in this package model portions of the OCL abstract syntax tree, |
| not extending the Ecore language as such: |
| </p> |
| <ul> |
| <li>{@link org.eclipse.emf.ocl.uml.Constraint}: top-level construct in |
| the AST; contains an {@link org.eclipse.emf.ocl.expressions.OCLExpression} |
| in some constraint context.</li> |
| <li>{@link org.eclipse.emf.ocl.uml.CallAction}: represents an invocation |
| of an {@link org.eclipse.emf.ecore.EOperation} in the OCL message model.</li> |
| <li>{@link org.eclipse.emf.ocl.uml.SendAction}: represents the sending of |
| a <code>Signal</code> in the OCL message model.</li> |
| </ul> |
| <p> |
| The {@link org.eclipse.emf.ocl.helper.IOCLHelper} also provides simple, but |
| flexible, support for |
| parsing OCL expressions: invariants in a classifier context, and pre/post |
| conditions and body conditions in an operation context. Evaluation is also |
| supported for invariant constraints. The helper is constructed with an |
| {@link org.eclipse.emf.ocl.parser.EnvironmentFactory} that creates the |
| necessary environments for parsing the client's metamodel. This allows clients |
| of other metamodels than Ecore (e.g., SQL, UML2) that describe software |
| systems in terms of classifiers to use OCL to expression constraints. |
| An environment maps the metamodel in question to the OCL parser's extended |
| Ecore metamodel. |
| </p> |
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