Page 1 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Chapter 19 Industrial Experience with Dassault Système Component Model

Page 2 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Overview qIntroduction qThe OM Component Model qDiscussion qLessons Learned

Page 3 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Introduction q CATIA l Dassault Systèmes main software product l 5 millions lines of code l clients l work places l C++ classes l 8000 components l Object Modeller: Own component model

Page 4 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Dassault Systèmes q The DS objective was not primarily: l To sell isolated OM components. l To sell the OM component framework. l To make their component model a standard. q The primary objective was: l To find a way to develop its software under the best conditions, and to provide to its customers with powerful adaptability facilities.

Page 5 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model The OM Component Model q The OM is quite similar to COM. qInterfaces: a set of method signatures l Component may support more than one interface.

Page 6 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model External view of OM components (a) External view of an OM component Interfaces (b) Heterogeneous application Other software entities OM components Dependencies

Page 7 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Using OM Components to Build Applications q In practice, there is no boundary between traditional development and component-based development. l DS applications are hybrids. l There is a Lack of support for explicit connections and assembly facilities. l DS does not aim to sell components, but extensible applications.

Page 8 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Component implementation Component inheritance Bases Extensions c c ? ? Interfaces Component implementation Delegation

Page 9 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Implementations qDS components are typically developed by different teams in different companies. qComponents are in fact a collection of elementary pieces of code, called implementations.

Page 10 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Extensions q Has two kinds of implementations: l Base implementations and extensions. l A component is defined by a base implementation. q An extension has two advantageous properties: l It does not change the identity of the component being extended. l It does not change the code of the component being extended

Page 11 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Component inheritance qSingle inheritance qInherits all its interfaces and all its implementations.

Page 12 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Conditional interfaces qThe interface will be returned to the client only if this expression evaluates to true. l 2D or 3D

Page 13 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Discussion q Has not develop a new language: l The OM can be seen as a layer superimposed on the C++ language. l Interfaces and implementations are represented as C++ classes. l OM constructions are indeed represented as code patterns and macros in C++ source code.

Page 14 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Different Kinds of Architecture (a) Physical architecture(b) OM components vs. frameworks Frameworks Dependency OM elements Other entities

Page 15 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Framework Evolution q A good component framework: l Satisfies development / maintenance needs. l Is easily mastered and understood by developers. q It is incorrect to believe that if a concept is simple, its use will also be simple: l “goto” and pointers l AddRef and Release

Page 16 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Evolution q An incremental process. l Model evolved permanently while CATIA software was in development. l Required different concepts and constructs to coexist, which created problems. q A bug may be due to: l Faulty implementation of the concept, l Undefined semantic hole l Inherent complexity. Specific training courses should be employed to ensure the correct use of the component model.

Page 17 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Industrial Perspective q Should Connectors be regarded as first class citizens? q Reexamination of the definitions of: l Connectors l Behavior l Architecture l Components

Page 18 Building Reliable Component-based Systems Chapter 19 - Industrial Experience with Dassault Système Component Model Summary qThe design of a powerful component model is shown to be a complex task. q The model has improved progressively over the years. q Very large systems must live with inconsistencies. l Training is needed to prevent misuse. l Tools for tracking invalid constructions. We have still to invent the CBSE environments of the future.