This document discusses OCL (Object Constraint Language) and its use with EMF (Eclipse Modeling Framework). It begins with an overview of why OCL is useful, describing it as a formal yet readable language for specifying business rules and constraints in UML models. It then explains what OCL is, how it is a typed, side-effect free expression language. The document outlines key OCL concepts like expressions, collections, and queries. It discusses how OCL is implemented in EMF, including validation capabilities and the OCLinEcore editor. It concludes with examples of when OCL is appropriate and information on downloading OCL tools.

1. OCL in EMFAshwani Kr Sharma, SAP Labs India

2. AgendaWhy OCL ?

3. What is OCL ?

4. When OCL ?

5. OCL in EMF ?Why OCL ? There are different categories of jobs,

6. Each category requires different skills.

7. Each plumber may have a different repertoire of skillsBusiness Rule:Each Job's assignee's skills include all the Job's category's requirements.….

8. UML SolutionsUML 1.x Use your favorite programming language

9. Ada/C/...

10. Magically inserted by proprietary code generator

11. UML 2.x Use a neutral specification language

12. The Object Constraint Language

13. State machine guards/actions

14. Class invariants

15. Operation bodies, pre/post conditions

16. Property initial/derived valuesWhy OCL ?Business Rule:Each Job's assignee's skills include all the Job's category's requirements.OCL-Job ::assignee.skills-->includes (category.requirements)

17. Why OCL ?In object-oriented modeling, a graphical model, like a class model, is not enough for a precise and unambiguous specification

18. The business rules are not captured.

19. Natural languages are ambiguous.

20. Formal languages is are useable to persons with a string mathematical background, but difficult for the average business or system modeler to useWhat is OCL ?Object Constraint Language (OCL), is a formal language to express side effect-free constraints. Users of the Unified Modeling Language and other languages can use OCL to specify constraints and other expressions attached to their models.

21. OCL is an add-on feature of UML, used to describe constraints, rules, specifications.What is OCL ?Natural/Formal Language compromise

22. natural language error prone

23. formal language unapproachable to many

24. Specification (not Programming) Language

25. declarative, modeling language

26. side effect free, no model changes, atomic execution

27. strongly typed, using UML generalizationOCL is typed !OCL is a typed language, so each OCL expression has a type. In a correct OCL expression all types used must be type conformant

28. OCL is a pure expression language OCL expression is guaranteed to be without side effect; it cannot change anything in the modelWhenever an OCL expression is evaluated, it simply delivers a value.

29. Mathematical operatorsInfix: +, -, *, / and, or, xor, implies
=, <>, <, >, <=, >= , =, <>Prefix: not, -4.0 * -5 'a' + 'b'Operators: mod, div, max, min, ...4.max(5)

30. OCL ExpressionsIfExpressionsif gender = Gender::MALE
then 'he'
else 'she'endifLet Expressionslet jack : Person = child('Jack'),
jill : Person = child('Jill')
in jack <> null and jill <> null