January Ron McFadyen1 Ch 9. Use-case model: drawing System Sequence Diagrams Elaboration Iteration 1: a simple cash-only success scenario of Process Sale beginning a wide-and-shallow design and implementation touches on many major architectural elements begins with a expansion of the Use Case Model with a System Sequence Diagram to clarify the input and output system events

January Ron McFadyen2 Simple cash-only Process Sale scenario 1. Customer arrives at a POS checkout with goods and/or services to purchase 2. Cashier starts a new sale 3. Cashier enters item identifier 4. System records sale line item and presents item description, price, and running total Cashier repeats steps 3-4 until indicates done 5. System presents total with taxes calculated 6. Cashier tells customer the total and asks for payment 7. Customer pays and System handles payment...

January Ron McFadyen3 System Sequence Diagram a picture showing actors and systems, lifelines, messages, time for a particular scenario for SSDs we will be ignoring an “activation box” that is normally placed on a lifeline :Cashier :System an arbitrary cashier a cashier object the software system to be developed We’ll see it as a black box

January Ron McFadyen4 Sequence Diagram object-oriented systems perform tasks by interacting with each other through the passing of messages a sequence diagram is an interaction diagram that emphasizes the messaging sequence A sequence diagram illustrates the dynamic behaviour of a system of objects The arrow we utilize ( ) is for procedural or synchronous messages – where the sender sends a message, transfers control to the receiving object, and waits for a response To indicate a return message and the explicit return of control, we use Ch 15 discusses interaction diagrams more fully

January Ron McFadyen5 System Sequence Diagram :Cashier :System Message at Time1 from :Cashier to :System Response at Time2 from :System to :Cashier Earlier events are above later events in the diagram time travels downward Time1 earlier than Time2: Time1 < Time2 message response

January Ron McFadyen6 Figure 9.1

January Ron McFadyen7 Figure 9.3 There are 4 system events shown here. The cashier will interact with the system in 4 ways. The events are given operation names: makeNewSale, enterItem, endSale, makePayment.

January Ron McFadyen8 January 2004 Assignment 1 Due: Friday Jan 23, Implement the ProductSpecification and Payment classes in any OO programming language (reference: Figure and section 20.11). Two additional classes you require are ProductSpecificationTest and PaymentTest (reference: Section 20.9). Hand in the source code for each of the above 4 classes and the results from running your tests. Note that the class methods expect valid data. 2.Create a use case model for an ATM. Details follow.

January Ron McFadyen9 January 2004 Assignment 1 Automated Teller Machine (ATM) The ATM system services one customer at a time. A customer is required to insert an ATM card and key in a personal identification number (pin). During one session, a customer may perform any number of transactions on any of their accounts. A customer may also choose to end the session and their card is automatically returned. A customer may make a cash withdrawal transaction from any of his/her accounts. Of course, the customer must have enough funds in the account to cover the withdrawal. A customer may make a deposit to any of his/her accounts. When making a deposit, the customer must place the deposit in an envelope and insert that into the appropriate slot when the systems requests. A customer may transfer money between any of their accounts. When a customer inserts their card into the ATM machine, they have three chances to enter the pin correctly. If they fail to do so, the card is not returned. After a transaction completes, the system prints a receipt and asks the customer if they will do another transaction or quit.

January Ron McFadyen10 January 2004 Assignment 1 Using the brief format in section 6.1, write separate use cases for the following uses cases: Session, Withdrawal, Deposit, Transfer, Inquiry, and Invalid pin. Relate these use cases with a mixture of “include” and “extend”. This is important for the following: Write the Main Success Scenario (reference Section 6.6 on Fully Dressed use cases) and a System Sequence Diagram for the Session use case (this one will have repetition similar to Process Sale use case). Create a use case diagram for your Use Case Model (reference Figure 6.2 and Figures 25.1, 25.2). To review, you must hand in: A Use case diagram (use Rational Rose or other tool) Brief formats for six use cases The main success scenario for the Fully Dressed use case