introduction to ocl
play

Introduction to OCL Fernando Brito e Abreu (fba@di.fct.unl.pt) - PDF document

Mar 10, 2023 •206 likes •708 views

Introduction to OCL Fernando Brito e Abreu (fba@di.fct.unl.pt) Universidade Nova de Lisboa (http://www.unl.pt) QUASAR Research Group (http://ctp.di.fct.unl.pt/QUASAR) Abstract Why formalization? Formalization in OO OCL types and

  1. Introduction to OCL Fernando Brito e Abreu (fba@di.fct.unl.pt) Universidade Nova de Lisboa (http://www.unl.pt) QUASAR Research Group (http://ctp.di.fct.unl.pt/QUASAR) Abstract  Why formalization?  Formalization in OO  OCL types and operators  Design by contract  Collection operations  Examples 1

  2. Why is formalization required?  Graphical elements of the diagrammatic specifications are very powerful and obvious  easy to understand how they fit together ;)  Modeling details, such as uniqueness and referential restraints, limitations and other constraints are expressed ambiguously  often they cannot be conveyed graphically  examples: Christian marriage, who‟s the boss, ... Who‟s the boss of the boss? Employee name : string boss 0..1 2

  3. Christian marriage On rails … 0..1 Train train_id : integer 1 front_car Car waggon_id : integer * waggons 1 loco Locomotive Waggon horse_power : integer number_places : integer 3

  4. The quest for formalization ...  Accuracy and unambiguity in specification is the aim of the branch of computer science known as “ formal methods ”  Several attempts have been made to combine them with object- oriented modeling … Formal methods in OO (1/4)  Extending and adapting an existing formal languagewith object-oriented constructs  Ex : Z++, Object-Z , VDM++  This approach is not in line with industrial practice trends to use the simple, but powerful, graphical notations in OOAD.  Most practitioners are not at ease in using traditionalformalspecification languages... 4

  5. Z, Z++ and Object Z  Z is a specification language developed by the Programming Research Group at Oxford University  "Understanding Z", J.M.Spivey, Cambridge U Press, 1988  Z is used for describing and modeling computing systems  It is based on axiomatic set theory and first order predicate logic  Z is written using many non-ASCII symbols  Z++ is an object-oriented extension of Z  "Z++, an Object-Oriented Extension to Z", Lano, Z User Workshop, Oxford 1990, Springer Workshops in Computing, 1991, pp.151-172  Object Z is another object-oriented extension of Z developed at University of Queensland, Australia  "Object Orientation in Z", S. Stepney et al eds, Springer 1992 An Object- Z extract … 5

  6. Formal methods in OO (2/4)  Complementing diagrammatic notations with some existing formallanguage constructs  Ex: Syntropy (subset of Z combined with OMT), ROOA (A. Moreira), Metamorphosis (J. Araújo)  Compromise solution, joining the benefits of graphicalmodelingand formallanguages  Drawback1: conceptual gap between formalisms  Drawback2: same as in previous approach A bit of Syntropy 6

  7. Formal methods in OO (3/4)  Use of a constraint language to express design by contractmodeling issues(B.Meyer)  Ex: BON (Business Object Notation) object-oriented method (Waldén 95).  Has a full-fledged textual assertion mechanism, allowing to specify system structure and semantics (constraints, invariants, properties of expected results)  Bridges the semantic gap but failed widespread acceptance (too tied to Eiffel language world)  Acceptance often comes from standardization ... BON: Elevator example 7

  8. Formal methods in OO (4/4)  The last and more promising road is OCL  Allows to specify invariants, preconditions, postconditions, guard conditions, and other types of constraints (restrictions)  Therefore supports design by contract as proposedby Bertrand Meyer  Is a part of the UML standard published by the OMG ( let‟s have a look at it ...)  Used in the standard itself to clarify the semanticsof the graphicalnotations (why?) Unclear semantics of the UML metamodel (example) Can the grandpa inherit from the grandson? 8

  9. Object Constraint Language  It is a formal, yet simple notation, to be used jointly with UML diagrams  Its syntax has some similarities to those of some OO programming languages  It is underpinned by mathematical set theory and logic, like in formal languages  However it was designed for usability and is easily grasped by those familiar with OO modeling concepts (particularly UML ones) Object Constraint Language  OCL brings the best of the previous approaches:  simplicity and powerfulness of graphical notations  preciseness and non-ambiguity granted by formality, in a usable and conceptually integrated fashion  Moreover, since it is a part of UML, it has become a de jure standard  also de facto because there is an increasing number of UML tools supporting OCL 9

  10. OCL syntax  OCL is strongly type checked  Style convention is Camel Case starting with:  Lower case letter: objects, attributes, operations  Upper case letter: classes  Dot notation is used for:  Attribute access  Operation access  Association end access (navigation in diagram) OCL examples Class : Operations :  Person, Date  boy.marries(girl), girl.age() Note : parameterless operations can be written with or without parenthesis Objects :  boy, girl Class attribute :  Person.allInstances Attributes :  boy.name Navigation through an  girl.birthday association :  boy.spouse.name 10

  11. Navigation example  Consider the object:  bill: Customer  Attribute access  bill.name  Operation access  bill.age()  Navigation through associations  bill.cards  bill.cards.color Class invariants  Invariants are constraints that represent conditions that must be met by all class instances, atall times.  Their context is, therefore, a class  Context can be represented differently: Example: -- every customer must be at least 18 years old OMG standard USE tool Customer context Customer inv CustomerAge: inv CustomerAge: age() >= 18 age() >= 18 11

  12. Design by contract PRE-CONDITION POST-CONDITION CLIENT Obligation Right SUPPLIER Right Obligation Operation assertions  Pre-conditions are constraints that must be true before an operation is executed  In the design by contract paradigm, they represent the rights of the object that offers the service or, if you want, the client responsibilities.  Post-conditions are constraints that must be true when the operation ends its execution  They represent the obligations to be fulfilled by the object that offers the service, or, if you want, the client rights. 12

  13. Operation assertions: example  The context of both pre and post-conditions is, therefore, an operation: This is a scope indicator Math::factorial(value:Integer):Integer pre :value >= 0 post :result = if value = 0 then 1 else value * factorial(value-1) endif OCL types OclAny is the superclass of all classes OclAny in OCL (even user defined ones) Real String Boolean Collection Enumeration Integer Set Bag Sequence 13

  14. OclAny  OclAny is the supertype of all model types  Features on OclAny are available on each object in all OCL expressions  To avoid name conflicts between features in the model and features inherited from OclAny, all names on the OclAny features start with „ocl‟ Features of OclAny (note: object is the instance of OclAny ) object = (object2 : OclAny) : Boolean -- True if object is the same object as object2 . object <> (object2 : OclAny) : Boolean -- True if object is a different object as object2 . object.oclType : OclType -- The type of an object 14

  15. Features of OclAny (note: object is the instance of OclAny ) object.oclIsTypeOf(t : OclType) : boolean -- true if t is the type of self post: result = (object.oclType = t) object.oclIsKindOf(t : OclType) : boolean -- true if t is either the type of object or one of its supertypes post: result = object.oclType.allSuperTypes ->includes(t) or (object.oclType = t) Features of OclAny: example mario: Student (Student is subclass of Person) mario.oclType -- results in Student mario.oclIsTypeOf( Student )-- is true mario.oclIsTypeOf( Person ) -- is false mario.oclIsKindOf( OclAny) -- is true mario.oclIsKindOf( Person ) -- is true 15

  16. OclType  All types defined in an UML model, or pre- defined within OCL, have a type  That type is an instance of the OclType metaclass  Access to OclType allows the modeler to access the model meta-level (reflexivity) Reflexivity: features of OclType (note: type is the instance of OclType ) type.name : String type.supertypes : Set(OclType) The name of type The set of all direct supertypes of type . post: type.allSupertypes->includesAll(result) type.attributes : Set(String) The set of names of the attributes of type.allSupertypes : Set(OclType) type , as they are defined in the model The transitive closure of the set of all supertypes of type type.associationEnds : Set(String) The set of names of the navigable type.allInstances : Set(type) associationEnds of type , as they are The set of all instances of type and all its defined in the model subtypes type.operations : Set(String) Example: The set of names of the operations of Customer.allInstances type , as they are defined in the model Transaction.allInstances 16

Recommend

INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION

INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION

TRAINING COURSE ON SOCIAL PROTECTION &amp; FORMALIZATION TRINIDAD AND TOBAGO MARCH 15, 2017 INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION Design of the NIS Assistance from the

547 views • 23 slides
INTRODUCTION Introduction 2/42 INTRODUCTION Alternations I am giving bread to the

INTRODUCTION Introduction 2/42 INTRODUCTION Alternations I am giving bread to the

Patterns of variation in the expression of case and agreement Andrs Brny Leiden University Centre for Linguistics 9 November 2019, BaSIS Workshop a.barany@hum.leidenuniv.nl INTRODUCTION Introduction 2/42 INTRODUCTION

1.37k views • 42 slides
Introduction Introduction Introduction Introduction Outline Motivation Failures

Introduction Introduction Introduction Introduction Outline Motivation Failures

Introduction Introduction Introduction Introduction Outline Motivation Failures Definition and concepts Process and product properties Principles SE Approaches Motivation Software and the economy The economies of

1.03k views • 49 slides
Introduction Introduction Introduction Nationwide Cause for Concern 1

Introduction Introduction Introduction Nationwide Cause for Concern 1

Introduction Introduction Introduction Nationwide Cause for Concern 1 https://www.cdc.gov/std/stats17/infographic.htm Introduction Epidemiology in Western Colorado CPHE Surveillance Data Report, May 2018 Chlamydia Epidemiology in Western

977 views • 39 slides
DAQ introduction Purpose of this talk : (1) Introduction for those who have not been in every

DAQ introduction Purpose of this talk : (1) Introduction for those who have not been in every

DAQ introduction Purpose of this talk : (1) Introduction for those who have not been in every meeting (2) Some ideas of diagrams for section 7.1 (Introduction) of TP. Giles Barr 25 Jan 2018, Pembroke College On DUNE, the reality is there is a

474 views • 10 slides
INTRODUCTION cf. Schneider, Chapter 1 INTRODUCTION THEY ARE OUT TO GET YOU INTRODUCTION WHAT

INTRODUCTION cf. Schneider, Chapter 1 INTRODUCTION THEY ARE OUT TO GET YOU INTRODUCTION WHAT

ADVANCED COMPUTER SECURITY INTRODUCTION cf. Schneider, Chapter 1 INTRODUCTION THEY ARE OUT TO GET YOU INTRODUCTION WHAT IS SECURITY? A systems security policies describe What the system is supposed to do Store and provide access

479 views • 16 slides
Overview Introduction to SMIL Introduction to W3C and XML Introduction to SMIL

Overview Introduction to SMIL Introduction to W3C and XML Introduction to SMIL

Overview Introduction to SMIL Introduction to W3C and XML Introduction to SMIL Writing a SMIL file Adding Media Objects Martin Halvey Clipping media files January 2008 Timing and Synchronising Layout World Wide

387 views • 14 slides
14 Introduction Introduction Bad guys can put malware into Example: hosts

14 Introduction Introduction Bad guys can put malware into Example: hosts

Introduction Introduction source Encapsulation ISO/OSI reference model message M application segment H t H t M transport network datagram H n H n H t M presentation: allow applications to frame link H l H n H t M interpret

583 views • 4 slides
Previous Lecture Introduction to SMIL 2 Introduction to W3C and XML Introduction to SMIL

Previous Lecture Introduction to SMIL 2 Introduction to W3C and XML Introduction to SMIL

Previous Lecture Introduction to SMIL 2 Introduction to W3C and XML Introduction to SMIL Writing a SMIL file Adding Media Objects Martin Halvey Clipping media files January 2008 Timing and Synchronising Layout

322 views • 8 slides
Lecture 1 Andreas Habegger Introduction Zynq Introduction Zynq Introduction Zynq PS vs. PL

Lecture 1 Andreas Habegger Introduction Zynq Introduction Zynq Introduction Zynq PS vs. PL

Introduction Zynq Lecture 1 Andreas Habegger Introduction Zynq Introduction Zynq Introduction Zynq PS vs. PL Processing System Processor Peripherals Data Buses AXI Bus Conclusion BTE5380 - Embedded Systems Octobre 2014 Andreas Habegger

1.81k views • 30 slides
2018.06 01 SMILE5 Introduction S E 5 02 Alpha Cloud M I L 03 Company Introduction 04

2018.06 01 SMILE5 Introduction S E 5 02 Alpha Cloud M I L 03 Company Introduction 04

2018.06 01 SMILE5 Introduction S E 5 02 Alpha Cloud M I L 03 Company Introduction 04 Project References S E 5 PART.1 SMILE5 Introduction M I L Introduction STORION-SMILE5 Residential Energy Storage System Inverter 5kW Output Input

1.06k views • 25 slides
Introduction to CICS Course introduction Course introduction What is CICS? What is an

Introduction to CICS Course introduction Course introduction What is CICS? What is an

Introduction to CICS Course introduction Course introduction What is CICS? What is an application server? Why use an application server? Course introduction Services provided by CICS How CICS applications are defined Scaling CICS to meet

1.84k views • 146 slides
Network Visualization Introduction Presented by Shahed Introduction Introduction Basic

Network Visualization Introduction Presented by Shahed Introduction Introduction Basic

Network Visualization Introduction Presented by Shahed Introduction Introduction Basic building blocks Node Links (relationship between nodes) Spatial information Network data

584 views • 9 slides
Introduction Introduction (1) Main argument of the paper: universities are not only

Introduction Introduction (1) Main argument of the paper: universities are not only

Le jugement des pairs comme outil de management des universits Peer-review as a management tool Christine Musselin (CSO, Sciences Po et CNRS) Avril 2013, Lirrsistible ascension du capitalisme acadmique Introduction Introduction (1)

590 views • 28 slides
Introduction Introduction to storage and to storage and filesystems filesystems Introduction

Introduction Introduction to storage and to storage and filesystems filesystems Introduction

Moreno Baricevic Gilberto Daz Axel Kohlmeyer Stefano Cozzini ULA ICTP CNR-IOM DEMOCRITOS Merida, VENEZUELA Trieste, ITALY Trieste, ITALY Introduction Introduction to storage and to storage and filesystems filesystems Introduction

1.19k views • 51 slides
JABLOTRON JA-100 introduction November 2011 Introduction Todays goals First introduction of

JABLOTRON JA-100 introduction November 2011 Introduction Todays goals First introduction of

JABLOTRON JA-100 introduction November 2011 Introduction Todays goals First introduction of the brand new JA-100 alarm system Visions Basic architecture System components Setting Help us with final validations You are the FIRST ones

1.69k views • 111 slides
1 Introduction Introduction Communication System Baseband an adjective that describes

1 Introduction Introduction Communication System Baseband an adjective that describes

Introduction Introduction Physical Layer Mobile network Global ISP Provides the means to transmit bits Basic Concepts of from sender to receiver, Data Transmission Defines the mechanical, electrical, and Home network timing

463 views • 7 slides
Welcome! Todays Agenda: Topic Introduction Course Introduction Team Practical

Welcome! Todays Agenda: Topic Introduction Course Introduction Team Practical

INFOGR Computer Graphics Jacco Bikker - April-July 2015 - Lecture 1: Introduction Welcome! Todays Agenda: Topic Introduction Course Introduction Team Practical Details Assignments Field Study State of

869 views • 62 slides
Introduction (00) RNDr. Martin Madaras, PhD. madaras@skeletex.xyz Introduction Introduction

Introduction (00) RNDr. Martin Madaras, PhD. madaras@skeletex.xyz Introduction Introduction

Virtual and Augmented Reality Introduction (00) RNDr. Martin Madaras, PhD. madaras@skeletex.xyz Introduction Introduction Who am I? What do I do here? 2 About me Short research bio: - 2014 - finished PhD at FMFI UK - 2014 2016 -

1.3k views • 39 slides
PRESENTATION The Introduction What is the Introduction ? The introduction prepares the audience

PRESENTATION The Introduction What is the Introduction ? The introduction prepares the audience

PRESENTATION The Introduction What is the Introduction ? The introduction prepares the audience for your presentation. It tells them what your presentation is about, why it is important, and finally, what to listen for in your speech. Get the

505 views • 3 slides
How to make a presentation with L A T EX? Introduction to L A T EX Introduction to Beamer

How to make a presentation with L A T EX? Introduction to L A T EX Introduction to Beamer

Introduction to Beamer Hafida Benhidour How to make a presentation with L A T EX? Introduction to L A T EX Introduction to Beamer Introduction to Beamer Hafida Benhidour Department of computer science King Saud University November

732 views • 49 slides
Shenzhen Cuilu jewelry Co., Ltd was founded in 1996 and its a large private enterprise

Shenzhen Cuilu jewelry Co., Ltd was founded in 1996 and its a large private enterprise

Introduction Introduction - - Brief Brief Introduction Introduction of of Cuilu Cuilu Group Group Introduction Introduction - - Brief Brief Introduction Introduction of of Cuilu Cuilu Group Group Shenzhen Cuilu jewelry Co., Ltd

147 views • 14 slides
Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org

Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org

V olunteer C ommunications N etwork (V-C-N.org) Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org Academy Course - 2012-02.24-2208 262: Introduction to ICS-214 : V-C-N.org : Slide: 1 V olunteer C

735 views • 34 slides
Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org

Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org

V olunteer C ommunications N etwork (V-C-N.org) Introduction to ICS- -214 214 Introduction to ICS Official Unit / Incident Log - A V-C-N.org Academy Course - 2012-02.24-2208 262: Introduction to ICS-214 : V-C-N.org : Slide: 1 V olunteer C

558 views • 18 slides

More recommend