UML and the Software Lifecycle

What is UML? Unified Modelling language Developed to enable IT professionals to model computer applications in a standard language-independent way. UML provides diagrams that increase the ease of understanding of an application under development

Main UML diagrams and the software Lifecycle Use Case Diagrams Activity Diagrams Class Diagram Sequence Diagrams State Diagrams Package Diagrams Deployment diagrams Requirements gathering Requirements analysis ANALYSIS DESIGN Software design Implementation

Requirements Gathering: Use Case Diagram shows SCOPE Source: IBM Rational

.

.

Use Case Diagrams Business requirements – essential use cases Guest Book spa Hotel self service subsystem Check valid room number Order food/ drink <<includes>> Request alarm call Guest

Each Use Case Describes a system function from a user’s perspective Details business events and users interaction with the system during that event Represents a system activity, a well-defined part of the system’s functionality Has a goal Supported by behaviour specifications Has a more detailed description, possibly specifying a number of scenarios or alternate courses of action

Use cases are initially defined at a high level and successively refined as the analysis and software development process unfolds. Williams 2004

The UML Class Diagram provides a model that can be easily translated into software components. Use case realisation includes identifying a set of classes with an understanding of how they work together to provide the functionality of the use case. Williams 2004

Class Diagram static structure of the system shows how different entities/objects relate Can be used in analysis to show... logical classes - things relating to the organisation And in software design to show.... implementation classes, which are the things that programmers typically deal with.

The class diagram is refined and modified through the lifecycle to add more detail relevant to the implementation

Example class diagram 1 0..* Is made up of <boundary> User Interface:: addmemberUI Startnewmember() Createnewmember() Select membertype() Recordpayment() <control> Control:: addmember Select membertype() Recordpayment() Createnewmember() <entity> Member Name Address Phone Mobile Email Type Createnewmember() Update membertype() Updatememberdetails() Deletemember() <entity> Filmclub Club name Location Night Time Contact Phone email Create filmclub() 1 0..* Is made up of

Williams 2004

Class diagrams can show Inheritance relationships Association relationships (like in E-R diagrams)

Activity Diagrams Activity diagrams are used to show sequences of activities. show workflows from start point to finish point detailing the many decision paths that exist in the progression of events contained in the activity. can be used to model higher-level business processes or low-level internal class actions. Swim lanes can be used to show who is responsible for an action

Activity Diagrams

Activity diagram with swimlanes Source: IBM Rational http://www.ibm.com/developerworks/rational/library/769.html

Statechart Diagram The statechart diagram models the different states that a class can be in and how that class transitions from state to state Only necessary for classes with 3 or more states.

Statechart Diagram Williams 2004

Sequence Diagrams Dynamic view of the system represent or model the flow of messages, events and actions between the objects in a system. show the calls between the different objects in their sequence for a use case or part of a use case used to design, document and validate the architecture, interfaces and logic of the system

Sequence Diagrams

Williams 2004

Component Diagram physical view of the system shows the dependencies that the software has on other software components (e.g. software libraries) in the system. The diagram can be shown at a very high level, with just the large-grain components, or it can be shown at the component package level. [Note: The phrase component package level is a programming language-neutral way of referring to class container levels such as .NET's namespaces (e.g., System.Web.UI) or Java's packages (e.g., java.util).]

Component Diagram Source: IBM Rational http://www.ibm.com/developerworks/rational/library/769.html

Deployment Diagram shows how a system will be physically deployed in the hardware environment where the different components of the system will physically run and how they will communicate with each other.

Deployment Diagram

Sources Williams, Laurie (2004) An Introduction to the UML Modelling Language IBM Rational - UML Overview http://www.ibm.com/developerworks/rational/library/769.html