Here are a couple more useful ocl operations on collections that were not explained in the reading or slides. On one hand, it finds its main application in the definition of the uml standard and a few other omg standards, being applied on the metalevel and being used, e. Ocl purpose let you practise reading and writing ocl constraints. Ocl linaye introduction constraints contextandself invariant preandpostcondition constraintsonattributes language accesstocharacteristics types variable collections oclfunction example otherfunctions oclistypeoft. Extensively used in the documentation of the uml language itself, and related. Ocl is a typed language, so that each ocl expression has a type. Object oriented software engineering using uml, patterns, and java chapter 8, object design. Llenguatge formal per expressar restriccions associades a models en uml. We look for some addon instead of a brand new language with full specification capability. Context links ocl constraint to specific type class, association class, interface, etc.
Object constraint language ocl integrity constraints 1 4 employee ssn firstname lastname birthdate sex salary address hiredate department number name locations 1 nbremployees project number name location hours 1 1 1 01 0 supervisor subordinates startdate 0 1 manages worksfor supervision controls workson 01 dependent name relationship sex birthdate 1 1. Height 150 object constraint language ocl invariant on associations. Contents this chapter contains the following topics. Object constraint language ocl integrity constraints 1 4 employee ssn firstname lastname birthdate sex salary address hiredate department number name locations 1 nbremployees project number name location hours 1 1 1 01 0 supervisor subordinates startdate 0 1 manages worksfor supervision controls workson 01 dependent name relationship sex birthdate 1 1 dependents.
This specification defines the object constraint language ocl, version 2. Introduction the object constraint language the ocl is used to specify constraints on objects in the uml. Properties can be combined to make more complicated expressi ons. Ocl object constraint language uml am beispiel eines. I when an ocl expression is evaluated, it simply returns a value.
Overview this document introduces and defines the object constraint language ocl, a formal language to express side effectfree constraints. Initially, ocl was merely a formal specification language extension for uml. This language, the object constraint language ocl,14, is targeted at two different areas of application. Every constraint is bound to a specific type class, association class, interface in the uml model its context. A constraint is a restriction on one or more values of an object oriented model. Object constraint language what is object constraint language. Object constraint language ocl pure expression language. Users of the unified modeling language and other languages can use ocl to specify constraints and other expressions attached to their models. The object constraint language ocl appeared as an e. The unified modeling language uml is the industrystandard notation for object oriented analysis and design 3. It can be used to express preconditions, postconditions, invariants, guard conditions, and results of method calls. Ocl constraints and expressions each ocl expression has a type and evaluates to a value, object or collection of objects within the system. Ocl describes the constraints and these constraints can be specified as invariants, precondition and postcondition. May 2006 object constraint language omg available specification version 2.
Object constraint language ocl une introduction master 2 ifpru module. Ocl is an industrial standard for object oriented analysis and design. Ocl provides a modeling language that allows the behavior to be embedded within the structural metamodels or provided as a complement to those metamodels. Ocl pre and postconditions allow you to specify contracts design by contract specify interfaces of components more precisely ocl usage tips keep constraints simple always give natural language comments for ocl exptressions use a tool to check your ocl. Suppose c is a collection of elements of type t, and t. Softwareengineering ocl linaye softwareengineeringocl. The object constraint language ocl is a declarative language describing rules applying to unified modeling language uml models developed at ibm and is now part of the uml standard. A constraint is an expression that evaluate to true or false as a query language queries are expressions that evaluate to a value true, 7 false and other values can be used to define new attributes and operations ocl expressions are always associated with a uml model.
Since its original standardisation many extensions have been added to the language and many more have been proposed. An important rule is that an ocl expression always evaluates to a specific object of a specific type. Object constraint language formal language for expressing constraints over a set of objects and their attributes. Ocl is a descendant of syntropy, a secondgeneration object oriented analysis and design method. Although both languages are used, they fail to fully address the nature of catalysis frameworks. As part of this process we encourage readers to report any ambiguities, inconsistencies, or inaccuracies they may find by completing the issue reporting form listed. The object constraint language ocl started as a complement of the uml notation with the goal to overcome the limitations of. I the object constraint language, ocl about ocl ocl aimed for the sweet spot between formal speci cation languages and use of english.
Appendix a object constraint language the object constraint language ocl, a standard part of uml 1. Object constraint language ocl ocl is a formal language used to describe expressions on uml models. Hence, object constraint language ocl comes to fill this gap. Une expression ocl decrit une contrainte a respecter et. Int pressturboboost presssignaljam context kittdriver inv. The object constraint language is a declarative language for describing rules that apply to unified modeling language models developed at ibm and now part of. The object constraint language ocl is a language to be used together with other uml tools like the class diagram, and its main purpose is to states constraints in a class model. A constraint is a restriction on one or more values of part of an object modelsystem. Ocl is not a programming language as a result it does not depict the program. A constraint is a restriction on one or more values of a model or system. The object constraint language ocl is commonly used to express assertions about object graphs, that is, instances of classes linked via attributes and references together referred to as properties 5. They also specify queries over objects described in a model. After obtaining a result, one can always apply another property to the result to get a new result value.
Contraintes exprimees avec ocl object constraint language. Conception par contrats avec uml ocl object constraint language. Pdf ocl contratos object constraint language lenin. Constraint animation using an objectoriented declarative. As a modeling language, ocl understands the models and so ocl code is much more compact than the equivalent java. Therefore, each ocl expression can be read and evaluated lefttoright. Rolebased authorization constraints specification using.
Ocl may now be used with any meta object facility mof object management group omg metamodel, including uml. Memento du langage ocl object constraint language v1. Object constraint modelbased assertion dldf fllwarmer and kleppe define a constraint as follows. Ocl 3 is easy to write and is a pure expression language. The same problems noted above could occur in a uml diagram that relies extensively on natural language to.
It is an expressionbased, sideeffectfree language that eschews mathematical symbols. The ocl is a standard query language, which is part of the unified modelling language uml set by the object. The object constraint language, in particular, is unable to express some of the behavioural aspects of these frameworks. A constraint is a restriction on one or more values a constraint is a restriction on one or more values of part of an object oriented model or system. Constraint invariant is a boolean ocl expression, evaluates to truefalse. The object constraint language ocl, which forms part of the uml 1. This paper describes a framework modelling language that addresses the inadequacies of these two. About the object constraint language specification version 2. Context object may be denoted within the expression using the keyword self.
The object constraint language ocl is a language that enables one to describe expressions and constraints on object oriented models and other object modelling artefacts. The object constraint language ocl started as a com. Parts of the syntax seem to have been influenced by smalltalk disclaimer opinions expressed here may be out of date. The object constraint language ocl was originally designed as an addon to the unified modelling language uml in order to facilitate writing textual constraints complementing the graphical specifications. Ocl object constraint language part of the uml standard. Uml diagrams can be supplemented with constraints specified in the object constraint language ocl 49. Ocl as specification language for object constraints. These predefined value types are independent of any object model and part of the definition of ocl. Object constraint language ocl une introduction pdf. Copies of specifications, available in postscript and pdf format, may be. Object constraint language object management group. For instance, typecasting with oclastype to a type that the object does not support or getting the first element of an empty collection will result in undefined. I ocl is a formal language used to describeconstraintson uml models i ocl isnota programming language.
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