Introduction to UML by Jan Pettersen Nytun, page 1 Introduction to UML

Introduction to UML by Jan Pettersen Nytun, page 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.

Introduction to UML by Jan Pettersen Nytun, page 3 Class and Object as Defined by Booch, Rumbaugh and Jacobson ClassClass : A description of a set of objects that share the same attributes, operations, relationships, and semantics. ObjectObject : 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.

Introduction to UML by Jan Pettersen Nytun, page 4UML 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.

Introduction to UML by Jan Pettersen Nytun, page 5 U M L Unified 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.~ ~ Modeling: Making a semantically* complete abstraction of a system. (* The formal specification of the meaning and behavior of something) Language: A graphical language ~

Introduction to UML by Jan Pettersen Nytun, page 6 UML Origins «specification» UML 0.8 «specification» UML 0.9 «specification» UML 1.0 «specification» UML 1.1 «specification» UML 1.2 «specification» UML 1.3 «refine» January 1997 (initial submission to OMG) September 1997 (final submission to OMG) Editorial revision With no significant Technical changes «specification» UML 1.4 «refine» 2001 «specification» UML 2.0

Introduction to UML by Jan Pettersen Nytun, page 7 Some of the UML Goals Define an easy-to-learn but semantically rich visual 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.

Introduction to UML by Jan Pettersen Nytun, page 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.

Introduction to UML by Jan Pettersen Nytun, page 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.

Introduction to UML by Jan Pettersen Nytun, page 10 [6] “Action Semantics UML Extensions let 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.”

Introduction to UML by Jan Pettersen Nytun, page 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

Introduction to UML by Jan Pettersen Nytun, page 12 [2]: The MDA Process [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. PSM Bridge Code Bridge

Introduction to UML by Jan Pettersen Nytun, page 13 MDA Example 1 Several Application Platform Independent Model CORBA Model EJB Model XML/SOAP Model Other Models XML/SOAP Code CORBA Code EJB Code Other Code PIM Reverse engineer First transformation PSM Second transformation Implementation

Introduction to UML by Jan Pettersen Nytun, page 14 MDA Example 2 Three Tier Solution – One Application PIM PSM EJB Comp. PSM Relational DB PSM Web PSM EJB Code PSM SQL Code PSM JSP Code

Introduction to UML by Jan Pettersen Nytun, page 15 Software Engineering Methods modeling language and a processMost methods consist of both a modeling language and a process (who is doing what and when). visual languageThe modeling language, the notation, typically include some visual language (different types of diagrams). toolA tool to support the method is also crucial.

Introduction to UML by Jan Pettersen Nytun, page 16 Three of the most popular methods Three of the most popular methods (What is the difference between a methodologist and a terrorist? Answer: You can negotiate with a terrorist.) OMTObject Modeling Technique, OMT, introduced by Jim Rumbaugh. OMT is considered to be strong on analysis and weaker in the design area. Booch Booch, introduced by Grady Booch (Rational Software). This method is considered to be strong in design and weak when it comes to analysis. OOSE 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.

Introduction to UML by Jan Pettersen Nytun, page 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)

Introduction to UML by Jan Pettersen Nytun, page 18 Abstraction Abstraction filter out nonessential details Abstraction is a fundamental human capability, it let us filter out nonessential details about a complex problem or structure. viewed at different levelsThrough 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.

Introduction to UML by Jan Pettersen Nytun, page 19 Modeling a modelmapping from the problem domain to a representationWhen you make a model you are making a mapping from the problem domain to a representation of the system you are modeling. a program execution can be regarded as a simulation of the behavior of the system.When you work object-oriented the model tends to be close to the system modeled, and a program execution can be regarded as a simulation of the behavior of the system. Reality System

Introduction to UML by Jan Pettersen Nytun, page 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.

Introduction to UML by Jan Pettersen Nytun, page 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.

Introduction to UML by Jan Pettersen Nytun, page 22 References [1] OMG Editor: Model Driven Architecture (MDA) (ormsc/ ) Accessed 19 August [2] Addison-Wesley, MDA Explained: The Model Driven Architecture™: Practice and Promise Anneke Kleppe, Jos Warmer, Wim Bast (Klasse Objecten, Soest, the Netherlands [6] Introduction to OMG's Unified Modeling Language™ (UML™) [accessed Aug. 2002] 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: