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Introduction to UML

Explore UML, a visual language for software system artifacts, applying object-oriented analysis and design concepts for modeling, specifying, and documenting system components. Learn about classes, objects, and the transition from Platform Independent Models (PIM) to Platform Specific Models (PSM) and executable code. Understand UML's value as an open standard supported by comprehensive tools.

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Introduction to UML

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  1. IntroductiontoUML

  2. UML Is Based on Object-oriented Concepts • A program will typically consist of objects that cooperate to solve a task. • An object will typically have attributes (data) and methods (behavior), this defines the state of the object and the manner in which the object operate. • Objects communicate by sending messages to each other. Sending a message to an object is the same as calling a method of the object.

  3. Class and Object as Defined by Booch, Rumbaugh and Jacobson • Class: A description of a set of objects that share the same attributes, operations, relationships, and semantics. • Object: A concrete manifestation of an abstraction; an entity with a well defined boundary and identity that encapsulates state and behavior; an instance of a class.

  4. UML • The UML is a language for • visualizing • specifying • constructing • documenting the artifacts of a software-intensive system • UML can also be applied outside the domain of software development.

  5. ~ U Unified: • Unification of earlier object-oriented analysis and design methods. • Same concepts and notation for different application domains and different development processes. • Same concepts and notation through the whole development lifecycle. ~ M • Modeling: • Making a semantically* complete abstraction of a system.(* The formal specification of the meaning and behavior of something) L ~ • Language: • A graphical language

  6. «specification» UML 2.0 «specification» UML 0.8 «specification» UML 0.9 «specification» UML 1.0 «specification» UML 1.1 «specification» UML 1.2 «specification» UML 1.3 «specification» UML 1.4 UMLOrigins 2001 «refine» «refine» Editorial revision With no significant Technical changes «refine» September 1997 (final submission to OMG) «refine» January 1997 (initial submission to OMG) «refine» 1996 1995 «refine»

  7. Some of the UML Goals • Define an easy-to-learn but semantically richvisual modeling language. • Unify ideas from other modeling languages and incorporate industry best practices. • Support higher-level development concepts such as collaborations (design patterns), frameworks and components. • Provide flexibility for applying different processes and mapping to different programming languages. • Support extensibility and specialization mechanisms so that the core concepts can be extended. • Provide a formal basis so that model interchange between different OO tools will be possible.

  8. The Value of UML • Open standard. • Supported by many tools. • Supports the entire development lifecycle. • Support diverse application areas. • Based on experience and needs of the user community.

  9. UML 1.3 Is Not a Visual Programming Language • UML 1.3 is a visual modeling language. It does not have all necessary visual and semantic support to replace programming languages.But the introduction of Action Semantics into UML has changed this! • But UML has a tight mapping to a family of OO languages like C++ and Java.

  10. [6] “Action Semantics UML Extensionslet you express actions as UML objects. An Action object may take a set of inputs and transform it into a set of outputs (although one or both sets may be empty), or may change the state of the system, or both. Actions may be chained, with one Action's outputs being another Action's inputs. Actions are assumed to occur independently - that is, there is infinite concurrency in the system, unless you chain them or specify this in another way. This concurrency model is a natural fit to the distributed execution environment of modern enterprise and Internet applications.”

  11. Executable UML • Abstracting away: • programming language, software organization • Class diagrams – showing “things” and structure (data): • classes, attributes, associations, constraints • Statechart diagrams – showing object lifecycle (control): • states, events, transitions, procedures • Action language – showing behavior (algorithm): • actions

  12. [2]: The MDAProcess PSM Bridge Code Bridge • [1]: “… separates the specification of system functionality from the specification of the implementation of that functionality on a specific technology platform.” • [2]: • First, you build a model with a high level of abstraction, that is independent of any implementation technology. This is called a Platform Independent Model (PIM). • Next, the PIM is transformed into one or more Platform Specific Models (PSMs). A PSM is tailored to specify your system in terms of the implementation constructs that are available in one specific implementation technology, e.g. a database model, an EJB model. • The final step is to transform a PSM to code. Because a PSM fits its technology very closely, this transformation is rather trivial. The complex step is the one in which a PIM is transformed to a PSM.

  13. PIM Reverse engineer First transformation PSM Second transformation Implementation Platform Independent Model CORBA Model EJB Model XML/SOAP Model Other Models CORBA Code EJB Code XML/SOAP Code Other Code MDA Example 1Several Application

  14. MDA Example 2Three Tier Solution – One Application PIM PSM Relational DB PSM EJB Comp. PSM Web PSM SQL Code PSM EJB Code PSM JSP Code

  15. Software Engineering Methods • Most methods consist of both a modeling language and a process (who is doing what and when). • The modeling language, the notation, typically include some visual language (different types of diagrams). • A tool to support the method is also crucial.

  16. Three of the most popular methods(What is the difference between a methodologist and a terrorist? Answer: You can negotiate with a terrorist.) • Object Modeling Technique, OMT, introduced by Jim Rumbaugh. OMT is considered to be strong on analysis and weaker in the design area. • Booch, introduced by Grady Booch (Rational Software). This method is considered to be strong in design and weak when it comes to analysis. • OOSE, (use cases ) introduced by Ivar Jacobson. OOSE is considered to be strong when it comes to behavior analysis and weaker in the other areas.

  17. UML Is Not a Development Process A development process defines: - Who is doing What, - When to do it, and - How to reach a certain goal • The UML is intentionally process independent, and defining a standard process was not a goal of UML. Different domain may require different processes. • But the UML authors promote a development process that is use-case-driven, architecture centric, iterative and incremental. (Example of method: RUP)

  18. Abstraction • Abstraction is a fundamental human capability, it let us filter out nonessential details about a complex problem or structure. • Through abstraction a system can be viewed at different levels.Often there is a hierarchic structure, each level of model is more precise than its parent. When developing a software system, code will be the lowest and most detailed level.

  19. Reality System Modeling • When you make a model you are making a mapping from the problem domain to a representation of the system you are modeling. • When you work object-oriented the model tends to be close to the system modeled, anda program execution can be regarded as a simulation of the behavior of the system.

  20. Why Do We Model? • Models give us a template that guides us in constructing a system. • If you want to make a building you first make a blueprint of the building to make, in the same way you should make a model of the system you want to make. As the complexity of systems increases, so does the importance of good modeling techniques. • Models help us visualize a system at different levels of abstraction, this makes it easier to manage complexity and to understand the system.

  21. More Arguments -Why Do We Model? • It is not expensive to experiment with multiple solutions when you operate on a high level of abstraction. • Models document the decisions we have made. • Models help for communication between different stakeholders.

  22. References [1] OMG Editor: Model Driven Architecture (MDA) (ormsc/01-07-01)http://www.omg.org/cgi-bin/doc?ormsc/2001-07-01Accessed 19 August 2002 [2] Addison-Wesley, MDA Explained: The Model Driven Architecture™: Practice and PromiseAnneke Kleppe, Jos Warmer, Wim Bast(Klasse Objecten, Soest, the Netherlands http://www.klasse.nl/english/mda/mda-introduction.html) [6] Introduction to OMG's Unified Modeling Language™ (UML™)[accessed Aug. 2002] http://www.omg.org/gettingstarted/what_is_uml.htm Grady Booch, James Rumbaugh and Ivar Jacobson:The Unified Modeling Language User Guide.Addison-Wesley, 1999 James Rumbaugh, Michael Blaha, William Premerlani, Frederick Eddy and William Lorenzen: Object-Oriented Modeling and Design. Prentice Hall, 1991 Martin Fowler with Kendall Scott: UML Distilled.Addison-Wesley, 1997 Terry Quatrani: Visual Modeling with Rational Rose and UML.Addison-Wesley, 1998 Rational software: http://www.rational.com/uml/documentation.html

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