Tool for Business Analysis - Use Case Diagrams

Jane goes to the website of Fit For Me. She logs into her account by providing her user name and password. Website displays her personal page. Sidebar on the left has links for her measurements, her recent orders and Billing History. On the top center, she sees 'New Arrivals' with icons of outfits from her favorite brand. Jane likes a cute dress and clicks on it. System takes her to 'customize' page and shows standard sizes as well as 'Jane's size' with measurements pre-populated based on her profile measurements. Jane checks 'her size' option, chooses pretty pink color and hits checkout button. The whole experience of choosing and ordering a 'tailor-made' outfit has taken 2 minutes.
This is an example of a Use Case for 'Select Custom-made dress' scenario. A pictorial representation of the same scenario is a Use Case Model. Use Case models and Use cases are effective tool s in a Business Analyst's tool-kit. Origin of use cases is attributed to Swedish computer scientist Dr. Ivar Jacobson, who is also considered father of Unified Modeling Language (UML) and Rational Unified Process (RUP). Dr. Jacobson gave the name Use Case in 1986 and it became an integral part of functional requirements specification by nineties; especially in emerging Object-Oriented methodology of software development.
A Use case represents an interaction between one or more actors and the system via various processes. The interaction is described in terms of the action to be taken by the actor or response received from the system. A Use case is always in the context of a system. Any interfacing system or module is also represented as an actor.
In our use case of ordering tailor-made clothes, some of the actors are:




Jane (Customer)
System(Fit For Me website)
Inventory System
Shopping Cart
Use Cases or Actions are

Log-in
Choose an Item
Customize Item
Checkout
Manage Profile
Use Case Model Building Blocks: An Actor represented as a person, A use case, represented with an oval, a system represented as a square and lines to show interactions or action are key building blocks of a use case diagram.
Dependencies: Includes(Uses) and Extends Different use cases within a module can have dependencies or relationships. There are two key dependencies - Includes or Extends. A use case includes or uses another use case if the 2nd use case is called at least once for the first use case. For example, for the check-in use case (at airport), assign seat and weigh bags will be two of the 'Include' use cases. A use case extends another use case when it adds special value to parent use case. Assign seat can be extended by a use case 'Assign window seat'. In our example, Extend and Includes (Uses) can be depicted as:
In summary, Use case diagram is an effective way of creating a pictorial representation of a system and representing interactions among various actors and components. It also helps define dependencies between various use cases. Use cases help clarify functional requirements. Business analysts should master this tool.
Bina Mehta is a Senior Business Analyst certified as CBAP and PMP. For CBAP and PMP prep classes in SF bay area, she recommends http://www.ultimateinsuccess.com/
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