Use Case Diagram on real world scenaios.pptx

Use Case Diagram. Role of use cases. Explain the process used to create use cases. Create use cases on real-world scenarios. Define process models of the basic concepts and constructs of a data flow diagram.

1. Learning Objectives Describe the role of use cases Explain the process used to create use cases Create use cases on real-world scenarios Define process models and describe there benefits Demonstrate an understanding of the basic concepts and constructs of a data flow diagram (DFD)

2. Overview Creating Use-Case diagrams and tables Purpose of Process Modelling Introducing Data Flow Diagrams (More next week)

3. Use Cases

4. What are Use-Cases? Use cases are methods of describing and documenting complex processes/activities Describes how the system reacts to an event that triggers the system Trigger is an event that causes the use case to be executed Event-driven modelling – everything in the system is a response to some triggering event Systems returns to waiting state after processing event

5. What are Use-Cases? All possible system responses to the event are documented Only details functional requirements For current system and new system Use cases not defined for simple processes Just use actual entry in Requirements Definition document

6. What are Use-Cases? Systems Analyst works closely and iteratively with user to obtain requirements

7. Use Case Diagram

8. Use Case Diagram Use case diagrams outline what a system does from the standpoint of an external observer. Use case diagrams are closely connected to scenarios. A scenario shows what happens when someone engages with the system.

9. Use Case Diagram Mini Scenario Here is a short scenario for a garage. “A car owner calls the garage to make an appointment for a yearly service. The receptionist finds the nearest empty time slot in the appointment book and schedules the appointment for that time slot. " We want to identify a single use case for the use case diagram for this scenario. Remember: A use case is a summary of scenarios for a single task or goal.

10. Use Cases Diagram – Identify the Actors As we read the scenario, define those people or systems that are going to interact with the scenario. “A car owner calls the garage to make an appointment for a yearly service. The receptionist finds the nearest empty time slot in the appointment book and schedules the appointment for that time slot. "

11. Actors An Actor is outside or external the system. It can be a : Human Peripheral device (hardware) External system or subsystem Represented by stick figure

12. Use Cases - Actors An actor is who or what starts the events in the use case. Actors are basically roles that people or objects play.

13. Use Case - Actors So as we read our scenario, name an actor. “A car owner calls the garage to make an appointment for a yearly service. The receptionist finds the nearest empty time slot in the appointment book and schedules the appointment for that time slot. " car owner Name an Actor

14. In Pairs or Groups - Fun Flowers Scenario (5 mins) Read the Fun Flowers hand out and name and drawn the actors at the edge of the paper. Credit card system

15. Use Cases The use case is a summary of scenarios for a single task or goal. For the garage scenario we are looking at the Use Case ‘Make Service Appointment’. Make Service Appointment

16. Use Cases The diagram below shows Make Service Appointment use case for the car garage linked to the other elements. The actor is a car owner. The connection between actor and use case is a communication. car owner Make Service Appointment Actor Communication Use case Brings

17. Use Case Elements The use case has three elements. The use case that represents a feature needed in a software system. The actor(s) who trigger the use case to activate. The communication to show how the actors communicate with the use case.

18. Use Case A major process performed by the system that to assist an actor Models communication between an actor and the system Represents the functionality provided by the system

19. Use Case Each use case represents a single function in which users interact with the system Labelled using a descriptive verb-noun phrase. Represented by an oval Make Service Appointment

20. Use Case - Relationships Represent communication between actor and use case Depicted by line or double-headed arrow line Also called association relationship Make Service Appointment car owner

21. Use Case Boundary A boundary rectangle is positioned around the edge of system to indicate how the actors communicate with the system. Make Service Appointment car owner

22. Over to You

23. In Pairs or Groups - Fun Flowers Scenario (5 mins) Identify the main use cases found in the Fun Flowers scenario, link them to the actor who triggers them. Credit validation Credit System Credit information

24. Use Case Include Relationship Represents the inclusion of the mandatory functionality of one use case within another Arrow is drawn from the base use case to the used use case with <<include>> on it car owner Make Service Appointment Check if existing customer <<include>>

25. Use Case Extend Relationship Relationship that extends the use case to include optional functionality Arrow is drawn from the extension use case to the base use case with <<extend>> above the arrow. car owner Make Service Appointment Check if existing customer <<include>> Check credit worthiness <<extend>>

26. In Pairs or Groups - Fun Flowers Scenario (5 mins) Devise the used use cases connected to the base use cases in the Fun Flowers scenario, create relationships with them. Credit validation Credit System Credit information Receive Payment Details <<include>>

27. Out of Class Create a use case diagram for the following library scenario. In our session next week each group will be asked to come up and explain their diagram. The borrower is identified using their membership card. The Librarian checks the validity of the membership card. The borrower presents one or more books to the Librarian. The Librarian checks the borrower’s records in his/her card indexing system and checks that the number of loaned books will be less than the maximum level. If acceptable, check out the books for the appropriate return date. Update the record for the borrower and update the status of the book.

28. Use Case

29. Use Case Reports (Brief Description for further research)

30. 5 Steps to Writing Use Case Reports Identify the major use cases Identify the major steps within each use case Identify elements within steps Confirm the use case with the user Cycle through steps 1 to 4 iteratively

31. 1. Identify the Use Cases Activities Typical Questions Asked For each use case, fill in the: name, description, ID and trigger Ask who, what, and where about the tasks and their inputs and outputs: What are the major tasks performed? What triggers this task? What tells you to perform this task? What information/forms/reports do you need to perform this task? Who gives you these information/forms/reports? What information/forms/reports does this produce and where do they go? Identify and fill in the easily identified inputs and outputs. If there are greater than nine use cases then group them into ‘packages’

32. 2. Identify Major Steps within Use Cases Activities Typical Questions Asked For each use case, fill in the major steps needed to process the inputs and produce the outputs Ask how about each use case: How do you produce this report? How do you change the information on the report? How do you process forms? What tools do you use to do this step (e.g., on paper, by email, by phone)?

33. 3. Identify Elements within Steps Activities Typical Questions Asked For each step within each use case , identify its triggers and its inputs and outputs Ask how about each step: How does the person know when to perform this step? What forms/reports/data does this step produce? What forms/reports/data does this step need? What happens when this form/report/data is not available? Each step should have at least one input and / or output

34. 4. Confirm the Use Case Activities Typical Questions Asked For each use case, validate that it is correct and complete Ask the user to execute the process using the written steps in the use case – that is, have the user role-play the use case

35. Elements of a Use Case form Use Case Name: Short Description: Trigger: Type: External Major Inputs: Description Source Major Outputs: Description Destination Information required: Major Steps Performed: ID Number: 2 Describes how students review listings of available modules for their course, add and remove modules from their course (where allowable), and review their course. Maintain student module enrolments Student enrols on to a degree course. Available modules request Available modules Module enrolment request Student modules file Student Avail. module list Student mod. enrlmnt Student Student Mod. enrlmnt file Student course 1. Student requests list of available modules. List of available modules for student’s course is generated. 2. Student adds module to course. Total hours is checked and if OK, module is added to student’s course. 3. Student removes module from their course. 4. Student reviews their course and modules attached to it. Student’s course id. Avail. module req. Course id. Module id. Mod. enrolmnt file Avail. module file Avail. module list Mod. enrolmnt file Basic Information Name, number and brief description Trigger – event that causes the use case to being External trigger – some from outside the system Temporal triggers – time-based occurrences Major Inputs and Outputs List sources and destinations Details Business processing steps taken Data inputs and outputs (read/writes)

36. Midlands Costume Rentals Ltd: Costume Availability Request Borrower Details Availability enquiry details Is the person making the enquiry a member? If they are, does the store have the required fancy dress costume? If there is a costume, is it on loan? Would you like it reserving ? Would you like to borrow it now? Loan Management System Availability Details

37. Over to You Create the use case document for the Midlands Costume Rentals Ltd: Check Costume Availability use case.

38. Midlands Costume Rentals Ltd: Costume Availability Request Use Case Name: Short Description: Trigger: Type: External Major Inputs: Description Source Major Outputs: Description Destination Information required: Major Steps Performed: ID Number: 2 Describes how the existing system responds when a customer requests availability of one or more Costumes and requests to loan available items (no reservation request made). Process Costume availability requests Customer contacts an in-store assistant (either in person or via telephone) to request availability of one or more costumes. Customer information (e.g. Borrower No.) Costumes(s) availability request Costume inventory Customer Customer Costume database Costumes matching the search request(s) Requested Costume(s) Customer In-store assistant Costume availability information 1. Find costumes matching customer’s request, whether the in-store assistant searches by title, actor, or category. 2. Provide availability information about each costume 3. Customer confirms wish to loan available costume(s). 4. In-store assistant validates customer. Total amount calculated for valid customer. New customers forwarded to Registration process. Search request details Costumes matching search request (e.g. costume id, location). Costume loans information . Customer information. Costume information. Selected costume information. 5. Issue Costume Borrower No. Costume No. Costume loans i nformation . Customer Basic Information Name, number and brief description Trigger – event that causes the use case to being External trigger – some from outside the system Temporal triggers – time-based occurrences Major Inputs and Outputs List sources and destinations Details Business processing steps taken Data inputs and outputs (read/writes)

39. Process Modelling – Getting started with DFDs

40. Process Modelling Technique for organising and documenting the structure and flow of data through a system’s processes Utilise information gathered during requirements determination A data flow diagram (DFD) is a technique that graphically depicts the flow of data through a system and the processing performed by that system

41. Process Modelling Four components Processes External agent Data stores Data flows Different notation systems may be used eg Gane & Sarson, Yourdon. Remember different methodology can use different tools to achieve the same objective.

42. An activity or function that is performed for some specific business reason Can be manual or computerised Naming convention: verb + noun i.e. start with a verb and end with a noun! DFD Components: Processes input i nput input output output output Id number Process Description 1 Manage Payroll Like Use cases Rules Processes cannot just have outputs else it’s a miracle process! Processes must produce an output in response to input else it’s a black hole! Processes must be described using verbs i.e. it is doing something

43. Logical and Physical Processes Logical Physical 1 Manage Student Marks 1.2 Mark Assessments 1.2.1 Calculate Aggregate Marks 1 Manage Student Marks School of Science & Tech 1.2 Mark Assessments Module Leader 1.2.1 Calculate Aggregate Marks appCalcAggMark.xls

44. Defines a person, department, other system or other organisation that lies outside the scope of the project but that interacts with the system customers, suppliers, contractors, government agencies, banks Provides net inputs to the system and receives net outputs from the system DFD Components: External Agents External Agent Like actors in Use cases. So name some external entitles Naming convention: Singular descriptive nouns eg Student, Customer, Client, Bank…

45. Depicts data at rest May represent data in File folder Card index Computer-based file Notebook Only system processes can read/write to data stores Data stores depicted on a DFD store all instances of data entities depicted on an ERD DFD Components: Data Stores id Description Naming convention: Plural descriptive nouns eg Students, Customers, possibly with “data”

46. Logical and Physical Data Stores Logical Physical D1 MS-Excel: Marks D1 Marks M1 File Cabinet: Orders M1 Orders D2 MS-Access: Student Records D2 Students M= Manual D= Computer Store

47. Depicts data that are in motion and moving as a unit from one place to another in the system Represents input to a process and output from a process Single data flows consist of a single meaningful data attribute Composite data flow is one that contains other data flows and are used in higher level DFDs for clarity DFD Components: Data Flows Discrete-time data flow Continuous-time data flow Control (non-data) flow Like comments in Use cases. Naming convention: Descriptive noun phrases and nouns. New patientID Existing patientID , New patient details, late student names.

48. DFD Components: Data Flows Data flows also depict data read/writes to data stores Data flows can be defined by data structures A data structure is a specific arrangement of data attributes that defines the organisation of data contained in a data flow A data attribute is the smallest piece of data that has meaning to the end-users of a business

49. Logical and Physical Data Flows Logical Physical D2 Students Create Student D2 Oracle: Students SQL Insert: New Student Valid Student Signed S1 Form: Valid Student Account Summary PRINTOUT: Account Summary Order HTML: Order Form 1 Process Order 1 Process Order Java OPS 1 Generate Account Summary 1 Generate Account Summary Sage Accounts 1 Validate Student Application 1 Validate Student Application Admin Office 2 Register Student 2 Register Student Register

50. A Fragment Logical DFD New/Updated borrower details New borrower details Membership details Updated borrower details Membership card D1 Borrowers 1 Manage Membership Borrower Borrower Existing borrower details Source Trigger Destination Data store from ERD

51. Over to You Create a Fragment DFD for one of the use cases in the fun flowers scenario.

52. Summary Describe the role of use cases Explain the process used to create use cases Create use cases Define process models and describe its benefits Demonstrate an understanding of the basic concepts and constructs of a data flow diagram (DFD)

53. Any Questions

54. References Dennis, A., and Wixom, B. H. (2003) Systems Analysis & Design , Second Edition, New York: John Wiley & Sons, ISBN 0-471-07322-9 Whitten, J., Bentley, L., and Dittman, K. (2001). Systems Analysis and Design Methods , 5th Edition, PP 313, McGraw-Hill Publishing. ISBN 0071180702. http://www.youtube.com/watch?v=KA4rRnihLII

55. How’s it going How are you feeling about the module, any areas of confusion, any changes you would like to see.

56. Mind Map – For you to think about Create a mind map of the information in this session.