CSC340 Information Systems Analysis and Design page 1/10University of TorontoFaculty of Arts and ScienceDept of Computer ScienceCSC340F – Information Systems Analysis and DesignDecember 2004Instructor: Steve EasterbrookNo Aids AllowedDuration: 2 hoursAnswer 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 gradeName: _______________________________________________________(Please underline last name)Student Number: _______________________________________________Question Marks1 ______________/202 ______________/203 ______________/204 ______________/205 ______________/20Total___________/100CSC340 Information Systems Analysis and Design page 2/101. [Short Questions; 20 marks total](a) [Goal Modelling – 5 marks] A telephone company manager has told you that her primary goal indeveloping 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 thisstarting 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 plancalculations”; “simplify discount structure”; etcWhy 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 numberof 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 andpayback period. Why might you need to know both in order to decide which of two differentdevelopment alternatives represents a better investment for a particular organisation?Return on investment (ROI) measures the ratio of benefits to investment made. Itallows you to compare development alternatives in terms of overall value for moneyinvested. However, it does not say anything about when (how soon) the return oninvestment will be realized.Payback period measures the length of time until the benefits of an investment start tooutweigh the costs, but does not measure the size of the return.You might need to know both because both can affect the desirability of proposedproject. In particular, an alternative with a higher return on investment might not bethe best to pick if the payback period is very long. E.g. We might prefer an alternativewith a lower ROI if the payback period is one year, to one with a higher ROI but apayback 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 representativetask using the new system, without providing any training, and measure the time it takesthem 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 weekor month of operation, and check that the system downtime is no more than 1 minute forevery 10,000 minutes of operation.Note: keywords such as “usability” and reliability” are not requirements on their own, they arecategories 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 reducecoupling between the functions of a system that are closer to the machine and those that are closer touser needs. Why is this reduced coupling useful? Describe a typical layered architecture and explainthe role of each of the layers.Reduced coupling is good because it separates the functions that might need to bechanged at different times. This is good for:Modifiability – changes can be made at one layer without affecting othersReusability – layers can be reused in similar systemsUnderstandability – 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 inputfrom the user, display results, and manage the appearance of the interface;Business Logic layer implements the basic functions provided by the system. Includes allthe entity classes, and control classes needed to implement the use cases;Data storage layer, responsible for persistent storage of the information users in thesystem. Includes a database component, or other mechanism to retain and query thedata.[Notes: other possible answers: 2-layers (essentially client-server); 4-layers model splits businesslogic 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 4/102. [Class Diagrams – 20 marks] Draw a class diagram to represent the following description ofdomain 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 oneelectoral district (known as a ‘riding’), and for each registration instance, details such as the date ofregistration and current status need to be stored. Eligibility is determined by address. Each person can beassumed to have one current address, and each address is in either a town or city. Some ridings contain severaltowns, 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 wouldyou modify your diagram to handle the following situations: (a) we may need to retain information on peoplewho no longer live in this province; (b) some people own property in more than one riding, and hence apply forregistration in more than one riding; (c) people with more than one
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