6/4/2014 CPSC , CPSC , Lecture 3 2 Overview of the Last Lecture Software Development Models Waterfall Model Evolutionary Models Incremental Model Spiral Model Unified Process Overview of UML History View models Using UML in UP
6/4/2014 CPSC , CPSC , Lecture 3 3 Overview of This Lecture Introduction to Case Studies Requirement Gathering Use Case Modeling Domain Modeling / Business Modeling Activity Diagram
6/4/2014 CPSC , CPSC , Lecture 3 4 Case Study 1: The Restaurant Example developed in the Practical Object- Oriented Design With UML by Mark Priestley, chapter 4. Support the day-to-day operations of restaurant by improving the processes of: Making Reservations Allocating Tables Current System is based on manual booking system: Hand-written forms in large folder.
6/4/2014 CPSC , CPSC , Lecture 3 5 Case Study 1: The Restaurant Current system uses manual booking sheets.
6/4/2014 CPSC , CPSC , Lecture 3 6 Case Study 1: The Restaurant Three sittings (slots) in an evening Booking can span more than one slot Each Booking records: Contact Name and Phone Number Annotation made for various events: Arrival of customer (Cross out record) Table switch (Arrow to new table) Cancellation Time to vacate Walk-In Customer
6/4/2014 CPSC , CPSC , Lecture 3 7 Case Study 1: Restaurant Problems with the manual systems: Slow Confusing and difficult to read No backup copies Hard to get useful management data Develop an automated computerized version.
6/4/2014 CPSC , CPSC , Lecture 3 8 Case Study 2: The Monopoly Game Chosen because of its familiarity. A game played almost in every country. Developed in the Applying UML and Patterns by Craig Larman, Chapter 3. The software version will run as simulation: User starts the simulation by indicating the number of simulated players. All turns are simulated with result (trace) printed.
6/4/2014 CPSC , CPSC , Lecture 3 9 Case Study 3: The Bicycle Renting Adopts a use-case driven object-oriented approach to develop a system to support the process of bicycle renting in a kiosk at East Coast Park, Singapore. Developed in the Software Engineering: An object- oriented approach by Bimlesh Wadhwa, Stefan Andrei, Soo Yuen Jien, 2007, McGraw Hill.
6/4/2014 CPSC , CPSC , Lecture 3 10 Where are we now? Requirement Analysis Design Implement Test Requirement Gathering Understanding the requirements. Business Modeling Understanding the problem domain.
6/4/2014 CPSC , CPSC , Lecture 3 11 Requirement: Overview Early phase of the development. Inputs: informal specification. Activities: create use case model. define use cases. create domain model. create glossary. create activity diagram.
6/4/2014 CPSC , CPSC , Lecture 3 12 Use Case View Intended to provide a structured view of the system's functionality. Description of how users interact with the system. Supported by UML use case diagrams. Serves as the starting point for all subsequent development. Three important definitions: Use Case Scenario Actor
6/4/2014 CPSC , CPSC , Lecture 3 13 Use Case and Scenarios Use Case: The different tasks that users can perform while interacting with the system. Scenarios: Are particular instances of the use case: Basic Course of Events: normal flow. Alternative Course of Events: optional flow. Exceptional Course of Events: erroneous flow.
6/4/2014 CPSC , CPSC , Lecture 3 14 Actor Roles played by users when interacting with a system, e.g.: Receptionist (makes bookings); Head waiter (assigns tables etc). Individual user may play one or more roles at different times. Often corresponds to certain level of access, e.g., logging into Lamar website as Staff or Student.
6/4/2014 CPSC , CPSC , Lecture 3 15 Use Case Diagram UML diagram to summarize the relationship between actors and use cases. Diagram Element: Actor Communication Use Case > Use Case Dependency Inherit (Actor Relationship) Constraints
6/4/2014 CPSC , CPSC , Lecture 3 16 Case Study 1: Use Cases A preliminary list of use cases: 1Record new booking. 2Cancel a booking. 3Record customer arrival. 4Transfer a customer from one table to another.
6/4/2014 CPSC , CPSC , Lecture 3 17 Case Study 1: Use Case Diagram Show use cases, actors and who does what. System
6/4/2014 CPSC , CPSC , Lecture 3 18 Use Cases Description A use case comprises all the possible interactions that a user can have when performing a given task. Often a dialogue between system and user. These are described as courses of events, or scenarios. A full description of a use case includes: a basic course of events; a number of alternative and exceptional courses.
6/4/2014 CPSC , CPSC , Lecture 3 19 Basic Course of Events Describes what happens in the normal case. For example, for Record Booking: Record Booking: Basic Course of Events Receptionist enters date of requested reservation; System displays bookings for that date; There is a suitable table available: Receptionist enters details (customers name, phone number, time of booking, number of covers, table number); System records and displays new booking.
6/4/2014 CPSC , CPSC , Lecture 3 20 Use Case Templates UML does not define a standard format for use case descriptions. Various templates have been defined to structure descriptions. Essentially a list of subheadings such as: Name Actors Courses of events
6/4/2014 CPSC , CPSC , Lecture 3 21 Other Use Case Description Template 1.Receptionist enters date of requested reservation; 3.there is a suitable table available: Receptionist enters details (customers name, phone number, time of booking, number of covers, table number); 2. System displays bookings for that date. 4. System records and displays new booking. This version emphasizes the exchange between user and system, e.g.: ActorSystem
6/4/2014 CPSC , CPSC , Lecture 3 22 User Interface Prototype During the use case modeling activity, it is usually useful to have a rough idea of the user interface, e.g.:
6/4/2014 CPSC , CPSC , Lecture 3 23 Alternative Courses of Events Describe predicted alternative flows. For example, if no table is available: Record Booking – No Table Available: Alternative Course of Event 1Receptionist enters date; 2System displays bookings; 3no table available: end of use case.
6/4/2014 CPSC , CPSC , Lecture 3 24 Exceptional Courses of Events Situations where a mistake has been made. E.g., allocate a booking to a small table: Record Booking – table too small: Exceptional course of events 1receptionist enters date; 2system displays bookings; 3receptionist enters details; 4system asks for confirmation of oversize booking; 5if no, use case terminates with no booking made; 6if yes, booking recorded with warning flag.
6/4/2014 CPSC , CPSC , Lecture 3 25 Shared Functionality Different use cases can overlap. E.g., Record Arrival: Record Arrival: Basic Course of Events head waiter enters date; system displays bookings; head waiter confirms arrival for booking; system records this and updates display. First two steps shared with Record Booking (even though different actor).
6/4/2014 CPSC , CPSC , Lecture 3 26 Use Case Inclusion Move shared functionality to a separate use case: Record Booking: Basic Course of Events (revised) receptionist performs Display Bookings; receptionist enters details; system records and displays new booking. Include this in other use cases, e.g.: Display Bookings: Basic Course of Events user enters a date; system displays bookings for that date.
6/4/2014 CPSC , CPSC , Lecture 3 27 The > Dependency UML shows inclusion as a dependency between use cases, labelled with the stereotype > on the dashed arrow: System
6/4/2014 CPSC , CPSC , Lecture 3 28 Case Study 1: Use Case Diagram (Revised) System Display booking
6/4/2014 CPSC , CPSC , Lecture 3 29 Actor Generalization The last diagram shows that the Receptionist can performs the Display bookings use case independently from the Record Booking use case. Head Waiters can also performs Display bookings use case. Introduce a more general actor Staff to show what the other two actors have in common. The initial actors are specializations of the general actor.
6/4/2014 CPSC , CPSC , Lecture 3 30 Actor Generalization Notation System
6/4/2014 CPSC , CPSC , Lecture 3 31 Use Case Extension Recording a walk-in can be described as an exceptional course of events: someone arrives but theres no booking recorded. It could also be a separate use case: a customer arrives and asks if there's a free table. Then, it can extend Record Arrival: even without a booking, the customer stays to eat.
6/4/2014 CPSC , CPSC , Lecture 3 32 Use Case Extension Record Walk-in: Basic Course of Events: 1Head waiter performs Display Bookings use case; 2Head waiter enters details (time, number of covers and the table allocated to the customer); 3System records and displays new booking. Very similar to Record Arrival use case. Can we simplify? > dependency is inappropriate. (why?) Record Walk-in is performed in some cases of Record Arrival, when there is no booking for the customer.
6/4/2014 CPSC , CPSC , Lecture 3 33 The > Dependency Use case extension is shown with a > dependency. Record walk-in optionally extends the functionality of Record arrival. States the constraint (condition) which causes the branch off. System No Prior Booking
6/4/2014 CPSC , CPSC , Lecture 3 34 Case Study 1: Complete Use Case Diagram System
6/4/2014 CPSC , CPSC , Lecture 3 35 Guidelines Use case: Should cover full sequence of steps from the beginning of a task until the end. Should describe users interaction with the system. Should not describe actual computations. Should be as independent as possible from any particular user interface design. Should only include actions in which the actor interacts with the computer. Use case diagram should be used to supplement the use case description, not as the main artifact.
6/4/2014 CPSC , CPSC , Lecture 3 36 Use Cases: Strengths Simple and Familiar Can be understood easily by untrained personnel, e.g., the customer. Involve the customer early in the development. Emphasize the user goals and perspective. Scale in term of sophistication and formality.
6/4/2014 CPSC , CPSC , Lecture 3 37 Use Cases: Problems Care must be taken to ensure the use cases are complete and unambiguous. Only actor initiated activities are recorded. Software requirement derived from use cases often mimics the manual system too closely. Preventing any innovative or more efficient way to be developed.
6/4/2014 CPSC , CPSC , Lecture 3 38 Domain Modelling Using UML diagram to construct a model of the real-world system: Understand the problem domain. Model recorded as a simplified class diagram. Seamless development: The same notation is used for analysis and design. The design can evolve from the initial domain model.
6/4/2014 CPSC , CPSC , Lecture 3 39 Domain Model Notation A subset of class diagram model elements are used. Class Name Attributes Class Association Name Multiplicity Class Generalization Constraints
6/4/2014 CPSC , CPSC , Lecture 3 40 Domain Model Notation Classes represent real-world entities. Attributes represent the data held about entities. Associations represent relationships between the entities. Generalization can be used to simplify the structure of the model. Constraints can be used to indicate conditions.
6/4/2014 CPSC , CPSC , Lecture 3 41 Case Study 1: Customers and Reservations Basic business fact: customers make reservations.
6/4/2014 CPSC , CPSC , Lecture 3 42 Defining a Relationship Give a name to the relationship: use a verb so that the relationship can be read as a sentence: A customer can make many reservations. How many people make a reservation? one principal contact whose details are held; that principal contact can make more than one reservation (e.g., by postponing the time); the expected number of diners can be modelled as an attribute of the reservation.
6/4/2014 CPSC , CPSC , Lecture 3 43 Case Study 1: Tables and Reservation Is table number an attribute of Reservation? Better modelled as a separate class: tables exist even if there are no reservations; other attributes of tables, e.g., size, can be stored.
6/4/2014 CPSC , CPSC , Lecture 3 44 Use of Constraints Not all domain properties can be shown graphically: e.g., it should be impossible to double-book a table. Constraints add information to models: written in a note connected to the model element being constrained.
6/4/2014 CPSC , CPSC , Lecture 3 45 Use of Generalization A superclass can be used to show the properties shared by different types of booking.
6/4/2014 CPSC , CPSC , Lecture 3 46 Correctness How do we know when a domain model is complete? we don't: there are lots of plausible models in most cases. Domain modelling is not an end in itself, but a guide to further development. Realizing use cases tests the domain model, and will usually lead to refinements.
6/4/2014 CPSC , CPSC , Lecture 3 47 Supplementary Documents Common Supplementary Documentation: Glossary. Activity Diagram. Glossary: A mini dictionary that captures concepts and vocabulary relevant in the problem domain. Avoids misunderstanding and facilitate communication. Activity Diagram UML diagram that describes activities.
6/4/2014 CPSC , CPSC , Lecture 3 48 Case Study 1: Partial Glossary Booking: an assignment of diners to a table. Covers: the number of diners for a booking. Customer: a person who makes a reservation. Reservation: a booking made in advance. Walk-in: a booking that is not made in advance.
6/4/2014 CPSC , CPSC , Lecture 3 49 Activity Diagram Similar to flow chart that describes sequence of activities. Useful in: Business Modelling (business workflow). Use Cases (interrelation and interaction). Design (algorithm, complex sequence etc). Often associated with several classes. One of the strengths of activity diagrams is the representation of concurrent activities.
6/4/2014 CPSC , CPSC , Lecture 3 51 Activity Diagram Action: Fundamental block in an activity diagram. Represents a unit of work (something is done). Automatic transition upon completion. Transition: Represents the control flow: it is simply a movement between actions. Initial and End Node: Show the beginning and ending points in an activity diagram.
6/4/2014 CPSC , CPSC , Lecture 3 52 Case Study 1: Activity Diagram Display Booking Enter Information [ Booking Exist] [No Booking] Confirm Arrival Record Walk-In Documenting the sequence when customer arrives. Note the interrelation of Record Arrival and Record Walk-In.
6/4/2014 CPSC , CPSC , Lecture 3 53 Concurrent Actions Independent actions which can be carried out at the same time (in parallel). Shown using forks, joins and rendezvous: Fork: One incoming transition and multiple outgoing transitions. Execution splits into multiple concurrent threads. Rendezvous: Multiple incoming and multiple outgoing transitions. All incoming transitions must occur before the outgoing transitions.
6/4/2014 CPSC , CPSC , Lecture 3 54 Representing Concurrency Join: Multiple incoming transitions and one outgoing transition. The outgoing transition will be taken when all incoming transitions have occurred.
6/4/2014 CPSC , CPSC , Lecture 3 55 Activity Diagram: Another Example Verify course not full Receive course registration request Check prerequisites Check special permission Complete registration [ok] [not ok] [ok] [not ok] Use Cases: Submit registration request. Register student: Verify prerequisites. Verify course enrolment. Verify special cases.
6/4/2014 CPSC , CPSC , Lecture 3 56 Swimlanes Activity diagrams are most often associated with several classes. The partition of activities among the existing classes can be explicitly shown using swimlanes. Further clarify where an action takes place.
6/4/2014 CPSC , CPSC , Lecture 3 57 Swimlanes: Example Verify course not full Receive course registration request Check prerequisites Check special permission Complete registration [ok] [not ok] Student Course Action taken by Student Action taken by Course
6/4/2014 CPSC , CPSC , Lecture 3 58 Where are we now? Requirement Analysis Design Implement Test Typical Artifacts: Requirement Specification. Use Cases: Use Case Description. Use Case Diagrams. Activity Diagrams. Glossary. Domain Model.
6/4/2014 CPSC , CPSC , Lecture 3 59 Summary Introduction to Case Studies Requirement Gathering Use Case Modeling Domain Modeling / Business Modeling Activity Diagram
6/4/2014 CPSC , CPSC , Lecture 3 60 Reading suggestions From [Wadhwa, Andrei, Soo; 2007] Chapter 3 From [Priestley; 2004] Chapter 4, sections 4.2 to 4.5 Exercises From [Larman; 2005] Chapters 1, 6 From [Stevens, Pooley; 1999] Chapter 11
6/4/2014 CPSC , CPSC , Lecture 3 61 Coming up next Analysis: [Priestley; 2004], Chapter 5 [Wadhwa, Andrei, Soo; 2007], Chapter 3 UML Class and Object Diagrams: [Priestley; 2004], Chapter 8 [Wadhwa, Andrei, Soo; 2007], Chapter 4
6/4/2014 CPSC , CPSC , Lecture 3 62 Thank you for your attention! Questions?