May-June 2001 ISISTAN Research Institute – Tandil, Argentina Software Design Methodologies: UML in Action Dr. Mohamed Fayad, J.D. Edwards Professor Department of Computer Science & Engineering University of Nebraska, Lincoln Ferguson Hall, P.O. Box Lincoln, NE

L2-S2Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 2 Lesson 2: Modeling

L2-S3Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Lesson Objectives 3 Understand modeling Discuss Model essentials Explore Different Models Understand the differences between a method and a process Understand the differences between multiple models and multiple views

L2-S4Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Define: –Standards –Methodologies –Method & Process –Model & View –Tools –Environments 4 Definitions

L2-S5Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Standards imply regulations, guidelines, rules, laws, and so on. Standards can dictate named methodologies, such as IEEE standards or DOD standards (Ex: DOD-STD-2167A). A standard alone is not sufficient on getting a task completed. Why? 5 Standards [Fayad-Laitinen 1998]

L2-S6Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Because standards focus on the attributes of the results instead of how the results will be achieved A standard also includes a type, model, or example commonly or generally accepted or adhered to, such a criterion set for usage or practices (moral standards) Standards applies to some measure, principle, model, and so on, with which things of the same class are compared to determine their quantity, value, quality, and so forth (standards of purity in drugs) 6 Standards [Fayad-Laitinen 1998]

L2-S7Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad A methodology is “a science of method or orderly arrangement” Webster. A methodology is used to refer to the very highest level of the way we do things. A methodology also refers to “a system of methods, as in particular science” The methodology we will consider here cover only the development of software applications. 7 Methodology [Fayad-Laitinen 1998]

L2-S8Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad A method implies a regular, orderly, logical procedure for doing something, such as a method of finding software requirements. Exs: Waterfall model, spiral model [Boehm84], and fountain model [Henderson-Selers90]. Jacobson defines a method as a planned procedure by which a specific goal is approached step by step [Jacobson92]. Examples of software design method are a set of work procedures, a set of notations, or a set of heuristics. 8 Methods or Techniques

L2-S9Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Software engineering methods can be divided into three major categories: 1. Process-Oriented Methods [Yourdon89] 2. Data-Oriented Methods [Martin90] 3. Object-Oriented Methods [Fayad93, Rumnaugh91, etc..] 9 Methods or Techniques

L2-S10Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 10 POM vs. OOM

L2-S11Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 11 Method Provides Foundation for Software Engineering

L2-S12Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 12 The Myth of the Single Software Development Method

L2-S13Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 13 How Many OO Methods Exist? UML

L2-S14Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 14 Engineering Process Hierarchy Engineering ComputerElectronics SoftwareHardware SASDOOT UML Scientific Area Standards Methodologies (Macrodevelopment Processes) Techniques (Methods) (Minidevelopment Processes) Processes (Microdevelopment Processes OMT Identify Classes Identify Attributes

L2-S15Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 15 Processes are Important for a new OO Teams New methods and tools introduce confusion Processes define exactly who, what, when, and how –“big-picture”

L2-S16Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 16 Method vs. Process Processes take OO methods out of the classroom and put them to work Theoretical Ideas Predictions Practical Concrete Actions Metrics

L2-S17Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 17 Defined Processes are Baseline for Improvements Can’t improve anything that you can’t repeat

L2-S18Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 18 Software Process Hierarchy

L2-S19Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 19 General Processes Must be Tailored to Your Projects

L2-S20Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 20 Identifying Appropriate Process Details Cost effective range –depends upon environment –specifies “who”, “what”, “when” –reference “how” Too Much not cost effective typically too much “why” Not Enough useless typically only “what”

L2-S21Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Building a model is a well-established human process. A model is a description of something. Models allow us to answer questions about a real thing before we build it. Models capture only those features deemed essential by model builders for their goals. A single thing might be represented by multiple model. Models can be validated. 21 Modeling – Definition

L2-S22Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 22 Model Essentials Simple Complete (most likely to be correct) Stable to technological changes Testable Easy to understand Visual or graphical [Fayad98]

L2-S23Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 23 Modeling Classifications [1] Tangible –Physical –Examples Mall Aircraft Intangible –Logical –Examples Flowcharts STDs DFDs

L2-S24Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 24 Modeling Classifications [2] Static –Object models –Domain models –DFDs Dynamic –Behavior models Flowcharts Petri-Net –Three properties: Control, Behavior, Time

L2-S25Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 25 Modeling Classifications [3] Object Model (class diagram) Control Model (STDs) Transformation Model (DFDs)

L2-S26Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 26 Modeling Classifications [4]: UML Static Type diagrams, CRC cards, class diagrams Dynamic or Behavior Activity diagrams, collaboration diagram, sequence diagram, and state diagram Implementation Component diagram & deployment diagram

L2-S27Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 27 Multiple Models vs. Multiple Views UML has 9 different models. This called “multiple models” and represents: –Abstraction, what and how, etc. It is not “multiple views” Multiple view represents: –Presentations –Levels, layers, slices, details –Scalability, accessibility, authorization, information hiding, dimensions

L2-S28Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad 28 Tools: Select Tools to Meet Specific Needs

L2-S29Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad What are the differences between multiple models and multiple views? T/F –UML stands for United Modeling Level. –Software design is part of UML. Define: Static models, dynamic models, transformation models What are the differences between a method and a process? 29 Discussion Questions

L2-S30Modeling May-June 2001 ISISTAN Research Institute – Tandil, Argentina, M.E. Fayad Discuss the following guidelines –Go Beyond the Problem Domain –Speculate About Likely Changes –Separate General Functionality from Specific Policy –Object should have Cohesive Interfaces –Objects Should Be Intelligent Agents –Objects Should Export Services –Avoid “Object Machismo” 30 Questions for the Next Lecture