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The '''Object Constraint Language (OCL)''' is a [[wikipedia:Declarative_programming|declarative language]] for describing rules that apply to [[UML School|Unified Modeling Language (UML)]] models developed at IBM and now part of the UML standard. Initially, OCL was only a formal specification language extension to UML. OCL may now be used with any Meta-Object Facility (MOF) Object Management Group (OMG) meta-model, including UML. The Object Constraint Language is a precise text language that provides constraint and object query expressions on any MOF model or meta-model that cannot otherwise be expressed by diagrammatic notation. OCL is a key component of the new OMG standard recommendation for transforming models, the Queries/Views/Transformations (QVT) specification. | '''What is Object Constraint Language?''' | ||
The '''Object Constraint Language (OCL)''' is a [[wikipedia:Declarative_programming|declarative language]] used for describing rules that apply to [[UML School|Unified Modeling Language (UML)]] models developed at IBM and now part of the UML standard. Initially, OCL was only a formal specification language extension to UML. OCL may now be used with any Meta-Object Facility (MOF) Object Management Group (OMG) meta-model, including UML. The Object Constraint Language is a precise text language that provides constraint and object query expressions on any MOF model or meta-model that cannot otherwise be expressed by diagrammatic notation. OCL is a key component of the new OMG standard recommendation for transforming models, the Queries/Views/Transformations (QVT) specification. | |||
Learn more with ☛ [[OCL Expressions|'''OCL Video Tutorials''']] | Learn more with ☛ [[OCL Expressions|'''OCL Video Tutorials''']] | ||
Different ways MDriven relies on OCL | Different ways MDriven relies on OCL: | ||
* As constraint definition | * As a constraint definition of a class | ||
* As description of derivation rule on derived attributes | * As a description of the derivation rule on derived attributes | ||
* As description of derivation of derived associations | * As a description of the derivation of derived associations | ||
* As ViewModel columns and Nesting definitions | * As ViewModel columns and Nesting definitions | ||
* As definitions for Visible and Enable state for ViewModel columns | * As definitions for Visible and Enable state for ViewModel columns | ||
* As expression of style information on ViewModel columns | * As an expression of style information on ViewModel columns | ||
* As expression for object presentation | * As an expression for object presentation of classes | ||
* Action Enable expression | * As Action Enable expression | ||
* State machine Guards | * As State machine Guards | ||
MDriven relies heavily on OCL and | MDriven relies heavily on OCL and is a very powerful tool to describe constraints, actions, and transformations in your model. | ||
[[OCL Expressions|'''OCL expression''']] must be without side effects. It is a query language and as such it is not expected to change data as the language is applied. In MDriven we do however want to change data when appropriate | [[OCL Expressions|'''OCL expression''']] must be without side effects. It is a query language and as such, it is not expected to change data as the language is applied. In MDriven, we do however want to change data when appropriate. We use the same syntax as OCL in something we call [[EAL – ExtendedActionLanguage.|'''EAL – ExtendedActionLanguage.''']] | ||
==== [[OCLps|'''OCLps''']] ==== | ==== [[OCLps|'''OCLps''']] ==== | ||
Revision as of 07:26, 12 January 2023
What is Object Constraint Language?
The Object Constraint Language (OCL) is a declarative language used for describing rules that apply to Unified Modeling Language (UML) models developed at IBM and now part of the UML standard. Initially, OCL was only a formal specification language extension to UML. OCL may now be used with any Meta-Object Facility (MOF) Object Management Group (OMG) meta-model, including UML. The Object Constraint Language is a precise text language that provides constraint and object query expressions on any MOF model or meta-model that cannot otherwise be expressed by diagrammatic notation. OCL is a key component of the new OMG standard recommendation for transforming models, the Queries/Views/Transformations (QVT) specification.
Learn more with ☛ OCL Video Tutorials
Different ways MDriven relies on OCL:
- As a constraint definition of a class
- As a description of the derivation rule on derived attributes
- As a description of the derivation of derived associations
- As ViewModel columns and Nesting definitions
- As definitions for Visible and Enable state for ViewModel columns
- As an expression of style information on ViewModel columns
- As an expression for object presentation of classes
- As Action Enable expression
- As State machine Guards
MDriven relies heavily on OCL and is a very powerful tool to describe constraints, actions, and transformations in your model.
OCL expression must be without side effects. It is a query language and as such, it is not expected to change data as the language is applied. In MDriven, we do however want to change data when appropriate. We use the same syntax as OCL in something we call EAL – ExtendedActionLanguage.
OCLps
Seeking the database with OCLps
OCLOperators
Certain important constructs
Methods
More articles:
Unique constraints on 1 to 1 links
GuardConstraints
ClassFromString
Understanding OCL with reference to SQL
Custom types and custom operations in OCL
A few words on linq
OCL by example