Software Engineering and Models

Transcription

1 Software Engineering and Models All engineering is supported by models and their associated methods and tools Various methods, rules, models used to a greater (or often) lesser extent in the past in software engineering The UML has become a single widely supported open standard and this has many obvious advantages

2 The Unified Modelling Language UML has in recent years become the de facto standard Topics to be considered include: the UML notations and what they mean how the UML notations can be used as part of a software development process extensions such as those for Real Time

3 History of UML 1990s: many different OO development methods each with their own modelling language, including Booch's OOD Rumbaugh's OMT Jacobson's OOSE and Objectory 1994 Rumbaugh, then 1995 Jacobson join Booch's Rational Unified Method then move to Unified Modeling Language UML1.1 adopted by OMG November 1997 UML 1.3 UML 2.0 adopted but older versions persist...

4 modelling languages models of systems describe some aspect of the system at a certain level of abstraction e.g. architectural model modelling languages are often diagrammatic (with corresponding text) like programming languages: define syntax and semantics/meaning

5 Motivation To describe and communicate abstractions of the system allowing analysis and design models document the system in an abstract way for interfacing and use

6 Modelling language Expressive can communicate all important aspects of the design at different levels of abstraction Unambiguous precise meaning User friendly supports a user s modelling and analysis needs Good tool support

7 Models of a system We will want to distinguish models on several axes. For example: static model describes the elements of the system and their relationships dynamic model describes the behaviour of the system over time Again, we may take a logical view: which parts logically belong together? physical view: which parts will run on the same computer?

8 Philippe Kruchten logical view: how does the system satisfy the functional requirements? process view: what are the threads of control? development view: how can the system sensibly be built? physical view: how will the software be deployed on hardware? plus the use case view: what should the system achieve?

9 The Unified Modeling Language The UML provides diagrams that allow one to visualise the results of analysis and design The UML is not a programming language process or methodology or guidelines for developing software a solution!

10 UML use in Object-oriented Analysis and Design Object-oriented analysis What are the domain objects? Describe in a domain object model Object-oriented design Describe the software solution in terms of collaborating objects, with responsibilities. The UML just a notation how much does the UML notation help or hinder?

11 Terminology Wars Issue of where analysis stops and design begins... More analysis oriented More design oriented

12 What is Visual Modeling? Item Order Modeling captures essential parts of the system. Dr. James Rumbaugh Ship via Business Process Visual Modeling is modeling using standard graphical notations Computer System Copyright 1997 by Rational Software Corporation

13 What is the UML? (from Rational) The UML combines the best of the best from Data Modeling concepts (Entity Relationship ) Business Modeling (work flow) Object Modeling Component Modeling The UML is the standard language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system It can be used with all processes, throughout the development life cycle, and across different implementation technologies

14 Rational Unified Process Iterative Architecture-centric Use-case driven Risk confronting

15 Unified Process structure Phases Process Workflows Inception Elaboration Construction Transition Business Modeling Requirements Analysis & Design Implementation Test Deployment Supporting Workflows Configuration Mgmt Management Environment Preliminary Iteration(s) Iter. #1 Iter. #2 Iter. #n Iter. #n+1 Iter. #n+2 Iter. #m Iter. #m+1 Iterations

16 Representing System Architecture Logical View Implementation View End-user Functionality Programmers Software management Use Case View System integrators Performance Scalability Throughput Process View Conceptual Deployment View Physical System engineering System topology Delivery, installation Communication

17 Models and diagrams UML: single model, many views, diagrams Simplified models to fit the context Not all systems require all views: Single process: drop process view Adding views: Data view, security view

18 Models, Views, and A model is a complete description of a system from a particular perspective Use Case Use Case Sequence Use Case Use Case Use Case State State Class State State Object Scenario Scenario Collaboration Models State State Component Scenario Scenario Statechart Activity Component Component Deployment

19 A diagram is a view into a model Presented from the aspect of a particular stakeholder Provides a partial representation of the system Is semantically consistent with other views In the UML, there are nine standard diagrams Static views: use case, class, object, component, deployment Dynamic views: sequence, collaboration, statechart, activity

20 Use Case Diagram

21 Class Diagram

22 Object Diagram

23 Component Diagram

24 Deployment Diagram

25 Sequence Diagram

26 Collaboration Diagram

27 Statechart Diagram

28 Activity Diagram

29 Architecture and the UML Design View Implementation View Classes, interfaces, collaborations Use cases Use Case View Components Process View Deployment View Active classes Nodes Organization Package, subsystem Dynamics Interaction State machine

30 Architecture and Iterations Use case Model Design Model Implementation Model Deployment Model Test Model Content