CSC340 Information Systems Analysis and Design page 1 10 University of Toronto Faculty of Arts and Science Dept of Computer Science CSC340F Information Systems Analysis and Design December 2004 Instructor Steve Easterbrook No Aids Allowed Duration 2 hours Answer all questions Make sure your examination booklet has 10 pages including this one Write your answers in the space provided This examination counts for 35 of your final grade Name Please underline last name Student Number Question Marks 1 20 2 20 3 20 4 20 5 20 Total 100 CSC340 Information Systems Analysis and Design page 2 10 1 Short Questions 20 marks total a Goal Modelling 5 marks A telephone company manager has told you that her primary goal in developing a new telephone billing system is to reduce the number of errors made on customers monthly bills Give two different types of question that could be used to develop a goal tree from this starting point and suggest an example goal that each question might elicit How questions to elicit lower level goals e g How would you reduce the number of errors might elicit subgoals such as improve data entry procedures automate rate plan calculations simplify discount structure etc Why questions to elicit higher level goals e g Why do you need to reduce the number of errors might elicit higher level goals such as improve image with customers reduce number of customers moving to competitor phone companies etc Notes Need specific example for each type of question and goal elicited to get full marks b Economic Feasibility 5 marks Explain the difference between return on investment and payback period Why might you need to know both in order to decide which of two different development alternatives represents a better investment for a particular organisation Return on investment ROI measures the ratio of benefits to investment made It allows you to compare development alternatives in terms of overall value for money invested However it does not say anything about when how soon the return on investment will be realized Payback period measures the length of time until the benefits of an investment start to outweigh the costs but does not measure the size of the return You might need to know both because both can affect the desirability of proposed project In particular an alternative with a higher return on investment might not be the best to pick if the payback period is very long E g We might prefer an alternative with a lower ROI if the payback period is one year to one with a higher ROI but a payback period of ten years CSC340 Information Systems Analysis and Design page 3 10 c Non functional requirements 5 marks Give two examples of non functional requirements and for each suggest a measure that could be used to test whether a system satisfies the requirement Two examples Usability e g The system shall be usable by novice users without any prior training Possible measure to test satisfaction Get sample users to carry out a representative task using the new system without providing any training and measure the time it takes them to figure it out and the number of mistakes they make Reliability e g The system shall be 99 99 reliable Possible measure to test satisfaction Measure mean time to failure for the first week or month of operation and check that the system downtime is no more than 1 minute for every 10 000 minutes of operation Note keywords such as usability and reliability are not requirements on their own they are categories of requirement Only give partial credit if there specific example requirements are missing d Software Architectures 5 marks Layered software architectures can be used to reduce coupling between the functions of a system that are closer to the machine and those that are closer to user needs Why is this reduced coupling useful Describe a typical layered architecture and explain the role of each of the layers Reduced coupling is good because it separates the functions that might need to be changed at different times This is good for Modifiability changes can be made at one layer without affecting others Reusability layers can be reused in similar systems Understandability easier to understand how the software works Must have at least two advantages Typical 3 layered architecture has Presentation layer responsible for the user interface Includes classes to accept input from the user display results and manage the appearance of the interface Business Logic layer implements the basic functions provided by the system Includes all the entity classes and control classes needed to implement the use cases Data storage layer responsible for persistent storage of the information users in the system Includes a database component or other mechanism to retain and query the data Notes other possible answers 2 layers essentially client server 4 layers model splits business logic layer into application layer responsible for controlling the use cases and domain entity layer for basic functions shared by different applications CSC340 Information Systems Analysis and Design page 4 10 2 Class Diagrams 20 marks Draw a class diagram to represent the following description of domain objects involved in developing a registration system for voters in provincial elections Each person can be either an eligible voter or an ineligible voter Eligible voters are registered in only one electoral district known as a riding and for each registration instance details such as the date of registration and current status need to be stored Eligibility is determined by address Each person can be assumed to have one current address and each address is in either a town or city Some ridings contain several towns while some large cities may contain more than one riding Be sure to include names and multiplicities on all associations and state any assumptions you make How would you modify your diagram to handle the following situations a we may need to retain information on people who no longer live in this province b some people own property in more than one riding and hence apply for registration in more than one riding c people with more than one property are required to designate one as their primary residence to determine which riding they can vote in Modifications a Either make the association from address to riding optional 0 1 or add an extra class for out of province address perhaps as subclass of address b Allow more than one address to be associated with a person and add address to the
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