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Explore use-case diagrams to depict system interactions, actors, and processes. Learn scenarios, flows, and step-by-step modeling for effective system design and documentation.
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www.hndit.com Use cases Week 05
www.hndit.com Use‐case diagram – Depicts the interactions between the system and external systems and users. – Graphically describes who will use the system and in what ways the user expects to interact with the system
www.hndit.com Use-case diagrams and use-case model • A use case diagram illustrates • a set of use cases for a system, • the actors of these use cases, • the relations between the actors and these use cases • the relations among the use cases.
A Scenario www.hndit.com • The scenario is an ordered sequence of interactions between the actor(s) and the system to accomplish a goal. It consists of: • Normal Flow • Alternate Flow • Sub-Flows • Exceptions
Normal Flow www.hndit.com • Normal flow is the best-case scenario, EX:
Sub-Flows www.hndit.com • Sub-flows identify the details of the steps in the normal flow, EX:
Alternate Flow and Exceptions www.hndit.com • Alternate steps identify remedies; exceptions signify failure, EX:
www.hndit.com Use cases diagram
www.hndit.com Use cases diagram
www.hndit.com The Process Modeling use cases Step 1: Identify business actors Step 2: Identify Business Requirements Use Cases Step 3: Construct Use‐Case Model Diagram Step 4: Document Business Requirements Use‐case Narratives
<< extends >> www.hndit.com Major component of a Use case Diagram Actor Inheritance Use case Inclusion Of a Use case by Another Actor to Use case Association Extension of a Use case by Another Notes System Boundary
www.hndit.com Use Cases: Describing Processes Use cases • a use case describes the sequence of events of some types of users, called actors, using some part of the system functionality to complete a process. • Describe what a system does, not how the system does • A series of interaction of a User with the System, which provides some concrete, measurable results to the User
www.hndit.com For example, to carry out the process of buying things at a store when a POST is used _ two actors must be involved: Customer and Cashier, _ the following sequence of events must be performed: The Customer arrives at a checkout with items to purchase. The Cashier records the purchase items and collect payment. On completion, the Customer leaves with the items
www.hndit.com use cases 1. One method to identify use case is actor-based: • Identify the actors related to a system or organization, i.e. find and specify all the actors by looking at which users will use the system and which other systems must interact with it. (b) For each actor, identifying the processes they initiate or participate in by looking at how the actor communicates/interacts with (or use) the system to do his work. 2
www.hndit.com . A second method to identify use cases is event-based. (a) Identify the external events that a system must respond to. (b) Relate the events to actors and use cases.
www.hndit.com Actor • An actor represents a type of users of the system or external systems that the system interacts with. • An actors may model anything that needs to interact with the system to exchange information: a human user, a computer system, an electrical or a mechanical device such as a timer. • _
www.hndit.com Who is an Actor? • The User of the system is usually the Actor • The Actor (and not the User) is shown sending and receiving messages to and from the System • Example: John the Branch Manager, John the Customer and John the Teller may be one and the same person • External Devices may also be Actors • e.g. ATMs, Keypads, Printers • External Systems may also be Actors • e.g.A Mainframe
www.hndit.com Finding Actors • Who provides/uses Information to/from the System? • Who Supports this Functionality? • Which other Systems will this System Interact with? • The External Devices (Keypads, Printers etc.) that the system will Interact with Process Comment: Produce first cut of the list of Actors, then Cull them after drawing Initial Use Case diagrams
www.hndit.com Actor: Variations • Primary Actor versus Secondary Actors: • Primary • The first or main Actor who uses the system • The main Actor who benefits from the system • e.g. Customer, Patient, Doctor • Secondary Actor: • The Actor who derives indirect benefits from or uses the system (e.g. Branch manager); Depends on Perspective • Direct versus indirect actors • Banking System: Teller VS Customer
www.hndit.com A high-level use case describe a process(Use‐case narrative)
www.hndit.com Relationships • associations • On a use case diagram, associations are drawn between actors and use cases to show that an actor carries out a use case. • Modeled as a solid line connecting the actor and the • use case • • May be bidirectional or unidirectional
www.hndit.com <<extend>> • complex use case in order to simplify the original case and thus extend its functionality. • The extension use case extends the functionality of the original use case. • Shows optional behavior of a Use Case • Depicted as an arrow headed line (either solid/dashed)
www.hndit.com Uses (or Include) <<include>> • The base use case explicitly incorporates the behavior of another use case. • The relationship between the abstract use case and use case that uses it. Abstract use case: a use case that reduces redundancy among two / more other use cases by combining the common steps found in those cases.
www.hndit.com Depends on <<depends on>> • A relationship between use cases indicating that one use case cannot be performed until another use case has been performed.
www.hndit.com Inheritance • • A relationship between actors created to simplify the drawing when an abstract actor inherits the role of multiple real actors
www.hndit.com Benefits – Facilitates and encourages user involvement – Provides a tool for capturing functional requirements – Provides an aid in estimating project scope, effort and schedule – Provides a tool for requirements traceability – Provides a framework for driving the system development project
www.hndit.com Online Shopping Portal| A case study • A customer visits the online shopping portal. A customer may buy item or just visit the page and logout. • The customer can select a segment, then a category, and brand to get the different products in the desired brand. • The customer can select the product for purchasing. The process can be repeated for more items. • Once the customer finishes selecting the product/s the cart can be viewed , If the customer wants to edit the final cart it can be done here. • For final payment the customer has to login the portal, if the customer is visiting for the 1st time he must register with the site, else the customer must use the login page to proceed. • Final cart is submitted for payment and card details and address(where shipment has to be made) are be confirmed by the customer . • Customer is confirmed with a shipment Id and delivery of goods within 15 days.
www.hndit.com • Actors • Customer • Administrator. • Use case (functionality) Allows the customer to view the different categories and further to different products within the brands eg. Allows the customer to shop online saying time and cost of customer. The portal provides a bill and an shipment Id which can be used to track the delivery status of the goods purchased by the customer .Category:. Customer Customers when enter the site and view the various products in different category. Authentication of the customer is done for the payment of the shopping done Customer can browses through the products available in the shop, can select some of them and put into the shopping cart. Customer can anytime change the items in the cart either by adding new items or by removing existing items. Customer proceeds towards the payment counter. Finalize product list of items he finally wish to buy and make the final payment. Administrator Updates the details of the different category ,segments etc Verifies the customer card details and records the details for shipment of goods.
www.hndit.com Library management system • A library contains books and journals. The task is to develop a computer system for borrowing books. To borrow a book the borrower must hold a valid library card, have no books overdue by more than one week, and have no outstanding fines. There is a limit of 6 books that can be borrowed by a student and 12 books by a staff member. • The library may have several copies of a given book. • It is possible to reserve a book. • Some books are for short term loans only. Other books may be borrowed for 3 weeks. Borrowers can extend the loans. • Give a use case description for the following use case: Borrow a copy of a book
www.hndit.com CASE STUDY: Stock Maintenance. Now a day’s people should purchase things in stores. It is the System used to maintain the product details and stock. So in this stock maintenance have the details about the product, purchase, sales and stock what are the stocks we had. The product details contain product code, Product name, Opening Stock and Prices. These details are maintained in database. In the purchasing function we must have the details about the store, quantity and also price.The Sales Details contain Date, Customer name, Product code, Quantity and Prices. The Stock Details contain product id, opening stock, purchase stock, current stock, and sales. The stock details are maintaining the database and view the stock between two dates
www.hndit.com Case Study :-RAILWAY RESERVATION SYSTEM Railway Reservation System is a system used for booking tickets over internet. Any Customer Can book tickets for different trains. Customer can book a ticket only if the tickets are available. Customer searches for the availability of tickets then if the tickets are available he books the tickets by initially filling details in a form. Tickets can be booked in two ways by i-ticket or by e-ticket booking. In case of i-ticket booking customer can book the tickets online and the tickets are couriered to Particular customer at their address. But in case of e-ticket booking and cancelling tickets are booked and cancelled online sitting at the home and customer himself has to take print of the ticket but in both the cases amount for tickets are deducted from customers account. For cancellation of ticket the customer has to go at reservation office than fill cancellation form and ask the clerk to cancel the ticket than the refund is transferred to customer account. After booking ticket the customer has to checkout by paying fare amount to clerk.
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