L9-OOAD-CaseStudy

CSC 7322 : Object Oriented Development

J Paul Gibson, A207 [email protected]

http://www-public.it-sudparis. http://www -public.it-sudparis.eu/~gibson/Teach eu/~gibson/Teaching/CSC7322/ ing/CSC7322/

OO Analysis & Design Case Study http://www-public.it-sudparis.eu/~gi http://www-public.it -sudparis.eu/~gibson/Teaching/CSC bson/Teaching/CSC7322/L9-OOAD-Ca 7322/L9-OOAD-CaseStudy.pdf seStudy.pdf 2010: J Paul Gibson

T&MSP: Software Engineering

CSC7322/OOAD-CaseStudy CSC7322/ OOAD-CaseStudy.1

Objectives

Analyse a natural language description of a problem to be solved using software, and clearly identify the boundaries of the system to be built Construct a UML description of the requirements, and in doing so resolve issues such as ambiguity, inconsistency/incoherence, incompleteness and over/underspecification. Add details to the UML in order to generate a (correct) design that can be used by Java programmers to implement the software solution

2010: J Paul Gibson


CSC7322/OOAD-CaseStudy.2

Case Study: A library

Overview and Context We wish to develop a system to help with the management of a library catalogue and the users. The library contains books, CDs and DVDs. The catalog is accessible to all clients; but only the library employees can make changes to the catalogue record: by adding/removing documents and clients; and changing the status of documents and clients. The system is being developed to modernize the current catalogue which is stored on written cards, and which is becoming too slow as the number of library documents is growing every year. Further, the current catalogue cannot be accessed by the clients and is only open to the library staff.

2010: J Paul Gibson




Problem Expression The library contains documents which are either internal or external. An internal document cannot be borrowed, but an external document can be borrowed (for a limited period of time) Clients can be added and removed from the library (by library staff). Each client has a name, address and unique identification number. Clients can be subscribed or unsubscribed. A subscribed client can borrow up to 10 documents. An unsubscribed client can borrow up to 3 documents.

2010: J Paul Gibson




Problem Expression … Documents are CDs, DVDs and books. There are CDs that are also a special kind of audio book. Every document has a location in the library (which notes the physical location of where it must be stored while not being used), and a unique identifier. There may be multiple copies of the same document in the library. No client can borrow more than 1 copy of the same document at any one time. Every document has the following information: title, author, year. Books also have publisher information, a genre (crime, SF, etc) and the number of pages. CDs also have information regarding the type of music (rock, pop etc) For DVDs we also record the length of the film and the age restriction/classification 2010: J Paul Gibson




Problem Expression … When a document is borrowed, a card is created on which is noted the client, the document and the date for return. Books can be borrowed for 2 weeks, CDs for a week and DVDs for 2 days. If a client has an overdue document then they are refused permission to borrow any further documents. At the beginning of each day, the list of overdue books is updated. Clients who return all borrowed documents that are overdue can immediately borrow another document (without waiting for the next day). A subscribed client who has more than 5 overdue books in total loses their subscription and automatically becomes unsubscribed. Only a library official can change the type/status of a client from unsubscribed to subscribed. 2010: J Paul Gibson




Problem Expression … The current state of the library can be read by all users: For each type of document (book, cd, dvd) we can see the current number of borrowing instances For each document we can see the current borrowers For each user we can see the current documents borrowed

2010: J Paul Gibson




Problem Expression … Long-term Statistics are available to all users of the library: For each type of document (book, cd, dvd) we can see the total number of borrowing instances For each document we can see the total number of borrowing instances For each user we can see the total number of documents borrowed

2010: J Paul Gibson




Problem Analysis Step 1 Find the actors and the system functions available to the actors. Using this information, draw the use-case diagram

2010: J Paul Gibson




Problem Analysis Step 2 Identify the classes in the system For each class identify the attributes/operations Identify the relationships between classes Using this information draw a class diagram Verify that the system « functions » - so that there is a flow of execution in the class diagram for each of the use-cases. 2010: J Paul Gibson




Problem Analysis and Design Step 3 For the document class (I hope you have one!): analyse the different states that a document can be in, and specify an invariant property Identify the ways in which the state of a document can change, and draw the corresponding state machine diagram

2010: J Paul Gibson




Problem Analysis and Design Step 4 For the client class (I hope you have one!): analyse the different states that a client can be in, and specify an invariant property Identify the ways in which the state of a client can change, and draw the corresponding state machine diagram

2010: J Paul Gibson




Problem Analysis and Design Step 5 For the operation borrow (I hope you have one) draw a communication diagram that shows the interactions that occur between a client, a document and a borrow card. Represent the same information in a sequence diagram

2010: J Paul Gibson




Problem Analysis and Design Step 6 For the operation return (I hope you have one) draw a communication diagram that shows the interactions that occur between a client, a document and a borrow card. Represent the same information in a sequence diagram

2010: J Paul Gibson




Problem Analysis and Design - Review You now have a partial description of the system to be developed (and problem to be solved) What other diagrams do you need to draw in order to have a more complete design model? Can you now suggest changes in order to improve the original English description --- think about problems you had when trying to transform the text into UML Are you ready to turn the design into Java code? Is it at a good level of abstraction? 2010: J Paul Gibson



L9-OOAD-CaseStudy

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