IMPORTANT NOTICE TO STUDENTS: These slides are NOT to be used as a replacement for student notes. These slides are sometimes vague and incomplete on purpose to spark class discussions. Software models and the Unified Modeling Language (UML) - Behavioral Diagrams CS 360 Lecture 9

Outline What is UML? Behavioral UML Diagrams System Boundary Use Case Diagram Use Case Scenarios Requirements Tracing Sequence Diagram State Diagram

The Unified Modeling Language UML: A general purpose visual modeling language for software systems. Designed to incorporate current best practice in modeling techniques and software engineering.

Behavioral UML Diagrams Emphasize what must happen in the system being modelled. Use Case Diagram Sequence Diagram State Diagram

The System Boundary Define what the system should/should not do: Shows other systems that use the system being built. Identifies where the system begins/ends System scalability boundaries System portability boundaries Defining System Boundaries Physical – Infrastructure, resources Logical – data types, interfaces Social – traditions, behavioral Economic – use of limited resources, benefits to society Political – community concern, legal issues

Team Activity Discuss and draw diagram(s) representing the system boundaries for your project. Physical – Infrastructure, resources Logical – data types, interfaces Social – traditions, behavioral Economic – use of limited resources, benefits to society Political – community concern, legal issues

The Use Case Diagram Graphical visualization of the interactions among the elements of a software system. Use Case Diagrams always provide: The System Boundary Defines the system in relation to external components. The Actors Individuals or external components that interact with your system. The Use Cases Actions that your system can perform by interacting with internal components and outside actors. The relationships between Actors and Use Cases.

The use case Diagram Identifying Actors

The use case Diagram Identifying Use Cases

The use case Diagram - Example System Boundary 4. Relationships 3. Use Cases 2. Actors

Use Case Scenarios Scenarios: Whenever possible, Use Cases should be kept simple. Scenarios: Another way of viewing a Use Case. Exactly one Primary Scenario per Use Case. “Scenario where everything goes as planned.” Zero to many Secondary Scenarios per Use Case. Captures errors, exceptions, branches, etc. of the main Scenario.

Use Cases – Requirements Tracing With a Requirements Specification document and a set of Use Cases, you effectively have two “databases” of functional requirements. Requirements tracing can be accomplished by creating a Requirements Traceability Table. If there’s a req that doesn’t map to any use case, then there is a missing Use Case. If there is a Use Case that doesn’t map to any req, then the set of reqs is incomplete. Use Cases Requirements UC 001 UC 002 UC 003 UC 004 R1 X R2 R3 R4 R5

Team Activity Discuss and create the initial Actors and Use Cases for your project. Generate your first Primary Scenario. Generate a Requirements Traceability Table based on the Use Cases that you have defined and your project Requirements.

The Sequence Diagram Shows Instance and actor interactions arranged in a time sequence. Sequence Diagrams always provide: The Instance Symbols Represents a class, object, or component. The Actor Symbols Entities that interact with or are external to the system. Lifelines Represents the passage of time as it extends downward. May begin with Instances and/or Actors. Activation Boxes Represents the time needed for Instances and/or Actors to complete a task. Also known as Focus Boxes. Message Symbols Represents how information is transmitted between Instances and Actors. Solid lines for requests, dashed lines for responses.

The Sequence Diagram - Example 1. Instance Symbols 5. Messages 2. Actor Symbols 3. Lifelines 4. Activation Boxes

The Sequence Diagram Sequence diagrams can become complex if they’re not bound. Generally, sequence diagrams are used to show Instance and Actor interactions for specific Use Case Scenarios.

Team Activity Discuss and create the initial Sequence Diagram for the Primary Scenario that you developed earlier.

The State Diagram Describes the different states of a software system. State diagrams can be used to describe the state of individual components, sets of components, or an entire software system. State Diagrams always: Identifies important component(s) to be analyzed. Represents a class, use case, object, subsystem, or entire system. Identifies the states: Unique conditions for the identified component(s) Identifies the events: Action that can be used to generate a component state change.

The State Diagram - Example 1. Components 3. Events 2. States

Team Activity Discuss and create a State Diagram for the user login interface of your project.