Chapter 4 Eventdriven Use Cases 5192021 1 Use
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Chapter 4 – Event-driven Use Cases 5/19/2021 1
Use Cases and Their Scope • Establish the scope of work. • Establish adjacent systems that surround the work. • Identify the connections between the work and the adjacent systems. • From the connections, identify the business events that affect the work. • Study the response to the event. • Determine the best response that the organization can make for the event. • Determine the product’s role in the response. • Determine the use cases for the product. • Determine the requirements for each use case. 5/19/2021 2
Finding the Business Events Each of the flows that enters & leaves the system is a business event Event Name - Input & Output EVENT NAME Display of rooms Information 5/19/2021 INPUT & OUTPUT Hotel Info(input) & List of Hotels 3
Business Events A business event takes place through the arrival of an incoming flow of information. The work contains a business use case to respond to this business event. 5/19/2021 4
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When a business event happens, the work responds by initiating a business use case. 5/19/2021 6
Example of business events • Suppose you bought book in a bookshop. You found it on the shelf, thought it was useful and interesting, and approached the cash desk. That moment, the instant you signaled your intention to buy the book, is the business event. • The sales assistant responded to this business event by scanning the bar code, asking you for the cover price plus any applicable tax, perhaps asking the credit card company for authorization, ringing up the sale at the cash register, and putting the book in a bag before handing it to you. • We call this response to the business event a business use case. 5/19/2021 7
Cont. • When you pay your credit card bill at the end of the month, it is a business event as seen from the point of view of the credit card company. The credit card company responds to this event (its business use case) by checking that your address has not changed and then recording the date and amount of your payment. 5/19/2021 8
Cont. • The work's response to the business event is to continue processing until all active tasks (the processes) have been completed and all data retrieved or stored. • You can think of the response as a chain of processes and their associated stored data. Note that the processes are surrounded by a combination of data stores and adjacent systems. 5/19/2021 9
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