1. Component Oriented Programming 1 Introduction to COP

2. Component Oriented Programming 2 Major Topics Define COP and its major objectives Discuss the importance of COP Define components and their characteristics Distinguish hardware components and software components Investigate the differences between OOP and COP Introducing component-based software engineering

3. Component Oriented Programming 3 Component Dictionary definition –A unit of, part of a model Hardware components Software components Differences?

4. Component Oriented Programming 4 What is a component? (1) 1.A component is a nontrivial, nearly independent, and replaceable part of a system that fulfills a clear function in the context of a well-defined architecture. A component conforms to and provides the physical realization of a set of interfaces. (Philippe Krutchen, Rational Software) 2. A runtime software component is a dynamically bindable package of one or more programs managed as a unit and accessed through documented interfaces that can be discovered at runtime. (Gartner Group)

5. Component Oriented Programming 5 What is a component? (2) 3. A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to third-party composition. (Clemens Szyperski) 4. A business component represents the software implementation of an “autonomous” business concept or business process. It consists of the software artifacts necessary to express, implement, and deploy the concept as a reusable element of a larger business system. (Wojtek Kozaczynski, SSA)

6. Component Oriented Programming 6 What is a component? (3) 5. A reusable part of software, which is independently developed, and can be brought together with other components to build larger units. It may be adapted but may not be modified. A component can be, for example, a compiled code without a program source, or a part of a model and/or design. --- D'Souza and Wills

7. Component Oriented Programming 7 What is a component? (4) 6. A software component is a software element that conforms to a component model and can be independently deployed and composed without modification according to a composition standard. --- Councill and Heineman

8. Component Oriented Programming 8 What are in common? A piece of software Independently deployable Composable Self-contained Reusable –A set of interfaces provided to, or required from the environment. –An executable code, which can be coupled to the code of other components via interfaces.

9. Component Oriented Programming 9 What are the differences? These definitions begin from the consideration of CBSE from different viewpoints and focus on different aspects of software engineering such as: –Different phases (design, implementation and run-time phases) –Business aspects –Executable or not –Architectural issues

10. Component Oriented Programming 10 Implications of Szyperski’s definition The following implications arise as a result of Szyperski’s definition: –For a component to be deployed independently, a clear distinction from its environment and other components is required. –A component must have clearly specified interfaces. –The implementation must be encapsulated in the component and is not directly reachable from the environment.

11. Component Oriented Programming 11 Implications of Councill & Heineman’s definition A software component simply cannot be differentiated from other software elements by the programming language used to implement the component. The difference is in how software components are used. The definition of Software components depends on the underlined component model.

12. Component Oriented Programming 12 What is CBSE CBSE: Component-Based Software Engineering –How to create reusable components –How to create software products with reusable components –Analysis, Design, Programming, Testing, Maintenance of component-based software –Requirements, Specification, Provisioning, Assembly of component-based software COP: Component-Oriented Programming

13. Component Oriented Programming 13 Why CBSE? The simplest answer: components are the way to go because all other engineering disciplines introduced components as they became mature & still use them. Use component paradigm to simulate “Software Integrated Circuit” to resolve software crisis. “Object orientation has failed but component software is succeeding” Udell, 1994 –Object technology does not include the notions of independence or late composition, mostly used to construct monolithic application. Configuring and integrating an individual object into some given system is not normally possible. –Object technology tends to ignore the aspects of economies and markets. Today only small amount of catalogs of class, class libraries, and frameworks exist. Components are independent units of deployment!

14. Component Oriented Programming 14 Commonality and Difference SP (Structured Programming) OOP (Object-Oriented Programming) COP (Component-Oriented Programming) –What are common? –What are different?

15. Component Oriented Programming 15 SPOOPCOP Divide and conquer for managing complexity break a large problem down into smaller pieces Yes Unification of data and function a software entity combines data and the functions processing those data. improve cohesion Yes Encapsulation The client of a software entity is insulated from how that software entity’s data is stored or how its functions are implemented. Reduce coupling Yes Identity Each software entity has a unique identity Yes Interface represent specification dependency divide a component specification into interfaces restrict inter-component dependency Yes

16. Component Oriented Programming 16 COP vs OOP and SP Other differences? Identify at least one more difference.

17. Component Oriented Programming 17 Composability –Software entity and its ability of being integrated with other entities SP – functions, procedures: low OOP – classes, objects: high COP – components: very high

18. Component Oriented Programming 18 The Interchangeability SP: Two different implementations can never be interchangeable. OOP: Two different objects implementing the same specification are interchangeable. COP: Two different components with different specifications are interchangeable as long as they satisfy those interface requirements for all client components.

19. Component Oriented Programming 19 Component Goals If you are asked to name three goals for using component technology, what are they? –Write down your wish list for CBD or COP

20. Component Oriented Programming 20 Component Goals 1.Conquering complexity 2.Managing change 3.Reuse

21. Component Oriented Programming 21 Conquering Complexity We are living in a complex world! “The world produces between 1 and 2 exabytes of unique information per year, which is roughly 250 megabytes for every man, woman, and child on earth. An exabyte is a billion gigabytes, or 10 18 bytes.” http://www.sims.berkeley.edu/research/pro jects/how-much-info/summary.htmlhttp://www.sims.berkeley.edu/research/pro jects/how-much-info/summary.html

22. Component Oriented Programming 22 YearAT&TBSDMINIXLinuxSolarisWin NT 1976V6 9K 1979V7 21K 19804.1 38K 1982Sys III 58K 19844.2 98K 19864.3 179K 1987SVR3 92K1.0 13K 1989SVR4 280K 19910.01 10K 1993 Free 1.0 235K 5.3 850K3.1 6M 1994 4.4 Lite 743K 1.0 165K3.5 10M 19962.0 470K4.0 16M 19972.0 62K5.6 1.4M 19992.2 1M 2000 Free 4.0 1.4M 5.8 2.0M2000 29M

23. Component Oriented Programming 23 Managing Change Change is inherent in software engineering. The user requirements change, specifications change, personnel change, budgets change, technology change, etc. etc. This means building for change, design for change, is necessary. It is important to place primary emphasis during architecture and design on the dependencies between the components, and the management of those dependencies.

24. Component Oriented Programming 24 Reuse Design and implement something once and use it over and over again in different contexts. This will realize large productivity gains, taking advantage of best-in-class solutions, the consequent improved quality, and so forth. Develop for reuse, and develop with reuse

25. Component Oriented Programming 25 CBSE Component-Based Software Engineering CBSE = COA + COD + COP + COM Two key activities: –Development for reuse –Development with reuse

26. Component Oriented Programming 26 Component Forms 1.Component specification 2.Component interface 3.Component implementation 4.Installed component 5.Component object

27. Component Oriented Programming 27 Component Specification The specification of a unit of software that describes the behavior of a set of Component Objects and defines a unit of implementation. Behavior is defined as a set of Interfaces. A Component Specification is realized as a Component Implementation.

28. Component Oriented Programming 28 Component Interface A definition of a set of behaviors that can be offered by a Component Object.

29. Component Oriented Programming 29 Component Implementation A realization of Component Specification, which is independently deployable. This means it can be installed and replaced independently of other components. It does not mean that it is independent of other components – it may have many dependencies. It does not necessarily mean that it is a single physical item, such as a single file.

30. Component Oriented Programming 30 Installed Component An installed (or deployed) copy of a Component Implementation. A Component Implementation is deployed by registering it with the runtime environment. This enables the runtime environment to identify the Installed Component to use when creating an instance of the component, or when running one of its operations.

31. Component Oriented Programming 31 Component Object An instance of an Installed Component. A runtime concept. An object with its own data and a unique identity. The thing that performs the implemented behavior. An Installed Component may have multiple Component Objects (which require explicit identification) or a single one (which may be implicit).

32. Component Oriented Programming 32 Summary A component is a reusable software element confirms to a component model Software engineering has gone through SP and OOP towards COP There are three goals for COP Interface and independently deployable are the unique features of COP comparing to OOP and SP There could have many different forms of components