Common Mechanisms of UML

Case Study: Library Management System 

• Problem statement 
• Vision document
• Glossary 
• Supplementary specification document

Problem statement 

• The library system is a web-based application which is employed for automating a library 
• It allows the librarian to maintain the information about 
• ⃝books 
• ⃝magazines 
• ⃝CDs 
• ⃝its users 
• Furthermore, it provides the following facilities to its users 
• ⃝Search for items 
• ⃝Browse 
• ⃝Checkout items 
• Return items 
• Make reservation 
• Remove reservation, etc. 
• For borrowing the item from the library, any user must get registered in the system initially 
• The users can search for any item in the library by using the 'search option' 
• If the user finds the item he/she is searching for in the library, he/she can checkout the item from the library 
• If the study material is not available in the library at the moment, the user can make reservation for that item 
• The moment the item is available, the user who first reserved for that item is notified first 
• If the user checks out the item from the library, the reservation gets cancelled automatically. The reservation can also be cancelled through an explicit cancellation procedure 
• The librarian is an employee of the library who interacts with the borrowers whose work is supported by the system 
• The system allows the librarian to perform the following functions with a lot of ease 
• Create 
• Update 
• Delete information about titles 
• Borrowers 
• Items and reservations in the system 
• The library system can run on popular web-browser platforms like Windows Explorer, Netscape Navigator, etc. It can be easily extended with new functionality

Vision document 

• The vision document gives a description of the higher level requirements of the system which specifies the scope of the system
• The vision document for the library system might be a support system 
• The library system lends the items like books, magazines, CDs to its registered users 
• This system takes care about the purchases of new titles for the library. The popular titles are brought in many copies 
• If the items like old books, magazines and CDs are out of date or in poor condition, they are removed 
• The librarian is employed in the library for interacting with the borrowers whose work is supported by the library system 
• Any registered user can make reservation for a book, magazine or CD that is currently unavailable in the library so that he/she is notified first when it is available in the library 
• The moment the book or magazine or CD is checked out by the borrower, the reservation is cancelled. The reservation is also cancelled through an explicit cancellation procedure 
• The librarian can easily create, update, and delete information about titles, borrowers, items and reservations in the system 
• The system can run on popular web-browser platforms like Windows Explorer, Netscape navigator etc. 
• It is easy to extend the system with new functionality

Glossary 

• Key terms are denoted in italics within the use case specifications. 
• Item: A tangible copy of a title.
• Title: The descriptive identifying information for a book or magazine. Includes attributes like name and description.
• Reservation: Whenever a borrower wishes to checkout an item that is not available due to previous checkout by a different borrower a request can be made (a reservation) that locks the borrower in as the next person able to checkout the item. 
• Actors: Borrower - Interactive actor who uses the library to search for titles, make reservations, checkout, and return items. 
• Librarian: Interactive actor responsible for maintenance of the inventory, acting on behalf of the borrowers, and general support of the library (non-automated as well). 
• Master librarian: Interactive actor, themselves a librarian, who is also responsible for maintaining the set of librarians for the system. 
• Registered user: Any interactive user for whom the system maintains a system account. This includes borrowers, librarians, and master librarians. Capabilities include basic login, browsing and searching for titles.

Supplementary specification document 

• Objective:  The purpose of this document is to define the requirements of the library system. This document lists the requirements that are not readily captured in the use cases of the use case model. The supplementary specification and use case model together capture a complete set of requirements of the system. 
• Scope: This supplementary specification defines the non-functional requirements of the system such as reliability, performance, support ability, and security as well as functional requirements that are common across a number of use cases. 
• Reference: None 
• Common functionalities: Multiple users must be able to perform their work concurrently. If the reserved item has been purchased or available, the borrower must be notified.
• Usability: The desktop user interface shall be Widows NT or Windows 2000 compliant. 
• Reliability: The system shall be 24 hours a day, 7 days a week and not more than 10% down time. 
• Performance: The system shall support up to 2000 simultaneous users against the central database of any given data. The system must be able to complete 80% of all transactions within 5 minutes.