Software Modelling Lecture Slides PDF - University of Birmingham

Week 3.2: Software Modelling (Part 1) Building Usable Software 2023-2024 What does UML include? Use What You Need. Probably You Don’t Need Everything. Activity Diagram Used to model (work)flows by identifying the steps...

Week 3.2: Software Modelling (Part 1) Building Usable Software 2023-2024 What does UML include? Use What You Need. Probably You Don’t Need Everything. Activity Diagram Used to model (work)flows by identifying the steps involved in a process and the conditions that govern the flow of work. Withdraw Money User Activity Diagram Goal Show dependencies and coordination between activities within the system. How the events in a single use case related to one another. How a collection of use cases coordinates to represent business workflow. Describe the parallel, branched and concurrent flow of the system. Uses Modelling business processes (how activities are performed, helping to identify bottlenecks, inefficiencies and opportunities for improvement). Use during the requirements elicitation process to understand the concurrent and parallel behaviour of the system or component. Requirement analysis to capture and clarify the dynamic aspects of a system’s behaviour. Activity Diagram: Elements Action: A task to be performed. Control Flow: Execution sequence. Initial node: Start of the flow. End node: Terminates the activity. Decision node: Represent a test condition to ensure that the control flow or object flow only goes down one path Merge node: Bring back together different decision paths that were created using a decision-node. Fork node: Split behavior into a set of parallel or concurrent flows of activities (or actions) Join node: Bring back together a set of parallel or concurrent flows of activities (or actions). Activity Diagram: Elements How to create Activity Diagrams? 1. Identify candidate use cases, through the examination of business workflows. 2. Identify pre- and post-conditions (the context) for use cases. 3. Model workflows between/within use cases. 4. Model complex workflows in operations on objects. 5. Model in detail complex activities in a high-level activity Diagram. Login use case: Activity Diagram Activity in Class Draw an activity diagram for the use case and modify profile photo. [Start] [User selects "Modify Profile Photo"] [System displays photo upload screen] [User uploads a new photo] [System validates the uploaded photo] [Decision: Is the photo valid?] [Yes] [System saves the new photo] [Notify user of successful update] [End] [No] [Notify user of invalid photo] [User cancels] [End] Activity Diagrams: Swimlane Also called functional bands. The activity diagram only represents the activities being performed, but swimlane describes who does what in a process or activity performed. Exercise: Train ticket machine The activity is started by commuter who needs to buy a ticket. The ticket machine will request trip information from the traveler. This information will include destination, number and type of tickets, (one way or round ticket). Based on the provided trip info ticket vending machine will calculate payment due and request payment options. Those options include payment by cash, or by credit. If payment by card was selected by traveler, another actor, Bank will participate in the activity by authorizing the payment. When payment is complete, ticket is printed and dispensed to the traveler. Cash payment might result in some change due, so the change is dispensed to the traveler in this case. Ticket vending machine will show some "Thank You" screen at the end of the activity. Exercise: Train ticket machine Example 1: Activity Diagrams Process Order: Description Once the order is received, the activities are split into two parallel sets of activities. One side fills and sends the order while the other handles the billing. On the Fill Order side, the method of delivery is decided conditionally. Depending on the condition either the Overnight Delivery activity or the Regular Delivery activity is performed. Finally, the parallel activities combine to close the order. Example 2: Activity Diagrams University Enrollment: Description An applicant wants to enroll in the university. The applicant hands a filled-out copy of the Enrollment Form. The registrar inspects the forms. The registrar determines that the forms have been filled out properly. The registrar informs students to attend in university overview presentation. The registrar helps the student to enroll in seminars The registrar asks the student to pay for the initial tuition. Example 2: Activity Diagrams Exercise: SmartBank Read the SmartBank description and draw an activity diagram for withdraw. Exercise: SmartBank Key Points Key Points Use case: High-level functionality Actors, use cases and relations Actor interactions and scenarios Improve communication among stakeholders Activity Diagrams: Internal workflow. Activities, actions, decisions. Step-by-step execution. Support sessions / Group formation Deadline: Wednesday, Feb 5th at 17:00 → Random allocation for those students who haven’t joined any group yet. Reading material The Unified Modeling Language User Guide 2nd Edition, by Grady Booch , James Rumbaugh, Ivar Jacobson Chapter 2 Chapter 3