cscc40 analysis and design of information systems...

CSCC40 midterm........October 29, 2005........page 1 of 13

UNIVERSITY OF TORONTOScarborough College

CSCC40 Analysis and Design of Information SystemsMid-term Test - ANSWERS

Saturday October 29, 2004 09:00 to 11:00 AM Rooms HW214 and HW215Duration: 2 hours. One 8 1/2 by 11 hand-written aid sheet is permitted.

Regarding the marking: ¸ usually means one mark(¸) or (x) usually means partial mark (could be correct, but badly stated,

or wording seems OK, but suspect you don't really know the answer)x means it's wrong

For some questions, the answers given here are not the only ones that might have got marks.

1. Indicate whether the statements following each paragraph are true or false. [7]

All projects, including IT projects, should support the business mission statement and theresulting business strategy. IT management has a vital role to play in realizing thebusiness mission.

True False

˛ r Information technology strategy defines physical design and information systems strategydefines logical design.

˛ r The information systems strategy sets goals for the information technology strategy.

r ˛ The information technology strategy sets goals for the business strategy.

r ˛ Information technology strategy sets goals for the information systems technology.

A value chain is the sequential set of primary and support activities that an enterpriseperforms to turn inputs into value-added outputs for its external customers.

True False

r ˛ Primary activities in a business' value chain include: human resource management and ITsystems development.

˛ rAn IT value chain is that subset of enterprise activities that pertain to IT operations, both toadd value directly for external customers and to add indirect value by supporting otherenterprise operations.

˛ r Sales and marketing activities are further on the value chain than procurement of rawmaterials.


2. Give one advantage and one disadvantage for each of the methods of requirements elicitation. [6]

method advantage disadvantagequestionnaire • for some questions get honest

answers if confidential• they can be used to collect data from

a large number of people

• get opinions, unsupported claims• limited to the types of questions that can

be asked• cannot clarify/explain questions or

answers• there are often many which are not

completed or returned by theparticipants

interviews • resolve, clarify if conflict orambiguity

• get sense of priorities of needs• get lots of information quickly• they permit topics to be explored in

depth with the interviewees

• time consuming, and therefore difficultto schedule users' time

• interviewer or interviewee bias can skewinformation

observation • see what users failed to mention oryou failed to ask

• see culture and habits• see actual, not filtered or biased or

omitted facts• it enables the evaluator to interact

and fully understand a situation orprocedure

• for security or other reasons, cannot seeall activity or data

• it may be an unusual day• persons being observed may change their

behaviour and affect the data beingcollected

• the above are not the only acceptable answers• see also midterm June 25 2002 questions 10• need to explain why if answer is brief as in "fast" or "easy" especially if another method is

faster or easier• describing the method is not giving the advantage or disadvantage

3. Explain why each of the following aspects of requirement management is important. [6]Write your answer from management's viewpoint, not from a programmer's viewpoint.

change management• control time and budget• make requestors accountable• always be aware of benefits and costs• allow prioritization• auditability of changes

definition of requirements attributes• able to know requirements clearly and check if system fulfils corporate goals• manage expectations• avoid disputes and errors• check compliance to standards, corporate values and practices

requirements tracing• auditability• prevent gold-plating• add security since each step can be examined

Generally management's concerns include time, money and success.


4. Improve each of the following requirements statements for a library system. [3]Use your imagination.

Recording book returns must be efficient.

process takes less than 3 seconds (any answer that is specific about efficiency)

The system must allow the addition of new material classifications. (classification = book, periodical, CD...)

Can add up to 20 new classifications

The system must be portable. (portable = capable of running on several machines/operating systems)

[name some platforms!]

5. Which of the following system development methodologies involves simultaneous [1]design and implementation of sub-projects?

a. Waterfall developmentb. Phased developmentc. Prototypingd. Parallel developmente. Throw-away prototyping

Only in Waterfall and Throw-away are you unable to do simultaneous design and implementation.

6. Answer the following questions about systems development methodologies [8](waterfall, prototype, spiral model, RAD, agile methods ...).And explain why you picked the methodology.

Pick the most appropriate methodology for a system to control anti-lock braking in a car.This is a safety-critical application, so you need a formal methodology with lots ofverification and validation of opportunities.

Pick the most appropriate methodology for a virtual reality system to support software maintenance.An exploratory methodology is needed because the requirements are hard to determine.

Pick the most appropriate methodology for a university accounting system that replaces an existing system.Requirements are stable. Waterfall will be fastest and easiest.

Pick the most appropriate methodology for an interactive system for railway passengers that finds traintimes from terminals installed in stations.

The interface is complex, so a prototype is needed, but the data structure and access isclear/known so a formal methodology can be used there.

• point for a methodology that is suitable• another point for demonstrated understanding of the problem domain


7. Complete a decision table based on the following statements. Use the blank table below. [4]It may have more rows and columns than you need.

No discount is given if the customer pays after 2 weeks or the order is less than $20.If the order is less than $50, the customer gets a 4% discount, other wise the customergets a 5% discount.

paid within 2 weeks Y Y Y Norder ≥ $50 Y N N -$20 ≤ order < $50 N Y N -order < $20 N N Y -give 5% discount Xgive 4% discount Xgive no discount X X

mark was based on how close you got to the above

8. Document the "Return Book" process for a library system. [5]You do NOT have to be complete; just put ONE representative item or point into each section.

procedure name of procedurereturns [result] OK or $ fine or error messagerequires [conditions under which it will work ... incl. input]

customer and book are on file, customer borrowed that book ...effects [what was achieved]

book returned, inventory updated, fine established, customer status changedmodifies [side effects.. e.g. global variables, state changes...]

amount of cash in library is increasedraises [exceptions]effects and modifies are somewhat similar, so allowed mix-up of answers in these two

9. A project to install a new library system has a favorable benefit to cost ratio, but it is rejected. [2]

Give a financial reason that might be given for rejecting the project.• poor ROI or payback period• money better invested elsewhere• can't afford it right now• not sure of non-tangible cost calculations

Give an operational reason that might be given for rejecting the project• company too busy to do it• to complex to achieve• not wanted for political reasons

the benefits and costs are both known, so contradictions to this in answers was not allowed

10. If two projects have very similar benefit to cost ratios and very similar payback periods, [3]why do you still need to calculate the return on investments for the two projects?

• ROI tells you whether or not putting money into something is actually a good investment• cash flow may not be favourable (depends on when the benefits or costs are incurred)


11. What argument might you give to justify completing a corporate data model, before [2]completing the analysis and design of a system that uses only part of the data in the model?

• corporate data model is stable and you need the big picture before developing functionality• future projects will be easier with less chance of having to make changes to the current

project• more likely to get current project done right• therefore this is a good investment

12. For each of the statements below indicate whether a low or high cohesion [4]or a low or high coupling is being described, and name the type described.

coupling cohesion type of cohesion low high low high or coupling

Module A contains two functions that often follow eachother. ¸ coincidental or temporal

¸ sequential

Module A always executes after module B. ¸ common or content

Module A updates the same data as module B, but for different reasons. ¸ stamp or data

Only module A contains the statements that change theentity status. ¸ none

¸ functional

Coupling is the relationship between two components. Cohesion is a condition within one component.Therefore if you specified both coupling and cohesion (whether high or low), you didn't get many marks.The first statement had two possible answers. You only needed to give one.The last statement could be interpreted two ways; the lack of relationships the module has with othermodules (therefore low coupling), or the similarity in the functions within the module (therefore highcohesion).

13. What analysis or design technique is being described in each case? [4]

_____Information hiding_____________ permits modules to be designed and coded without concern forthe internals of other modules. Only the access protocols of a module need to be shared with theimplementers of other modules. It simplifies testing and modification by localizing these activities toindividual modules.

_____Modularity____________________ derives from the architecture. It is a logical partitioning of thesoftware design that allows complex software to be manageable for purposes of implementation andmaintenance. The logic of partitioning may be based on related functions, implementation considerations,data links, or other criteria. It does imply interface overhead related to information exchange betweenmodules and execution of modules.

_____Abstraction____________________ is a means of describing a program function, at an appropriatelevel of detail. At the highest level, a solution is stated in the language of the problem environment(requirements analysis). At the lowest level, implementation-oriented terminology is used (programming).It can be compared to a model which incorporates detail only to the extent needed to fulfill its purpose.

______Stepwise refinement_____________ is a top-down approach where a program is refined as ahierarchy of increasing levels of detail. This process may be begun during requirements analysis andconclude when the detail of the design is sufficient for conversion into code. Processing procedures anddata structures are likely to be refined in parallel.


14. Shown below is an input screen for a collection agency application. For any three of the [6]following characteristics of good interface design, explain how this input screen demonstratesor does not demonstrate the characteristic.

affordance mapping function mental modelforcing function feedback automatic learning

characteristiccompliance

Y/N explanationCheck the definitions.There were lost of examples in this screen for most of the characteristicsNote that a help button is not automatic learning...

it's used when automatic learning is not possible!

15. What three models are created during the analysis phase of a software development process? [6]What is the purpose of each?

model name model purposedata relationship among object and entities

function describes what the system doesbehaviour describes how the system works

Process was also an acceptable answer.Some partial marks were given for wrong but somewhat reasonable answers. For example somestudents used ERD, DFD and hierarchy chart as model names.


16. Consider a MEETING entity with the following attributes. [3]MEETING (CourseName, CourseTitle, Day, Time, BuildingName, RoomNumber, Address)

This is already in first normal form (1NF) but it is not in 2NF or 3NF. Fix the problem.You may assume that

• Address functionally depends on BuildingName• CourseTitle functionally depends on CourseName

answer =BUILDING (BuildingName, Address)COURSE (CourseName, CourseTitile)MEETING (CourseName, Day, Time, BuildingName, RoomNumber)

17. What are the names of the following two conventions for data flow diagrams? [2]

top one is Gane & Sarsonbottom one is DeMarco & Yourdon

18. You are preparing the data dictionary for an order processing system. The company already has [3]several systems with which the order processing system must interface: distribution/deliverysystem, customer billing system, inventory system, etc. Explain the purpose of each of thefollowing data dictionary entries, and give an example of each.

External Entity's alias/alternate nameThe entity may be present in other systems with another name. Need to know that in orderto avoid design and implementation errors.

Data Flow's volume and frequencyOptimizationTells you whether or not it's worth implementing

Attribute/Variable's prompt/column headerConsistency of presentation to users.[where the attribute is stored in the database is described in data structures, not here]

19. Indicate which type of diagram or documentation provides the view listed below. [5]A view may be present in more than diagram or documentation.

ERD DFDhierarchydiagram

datadictionary

dialoguechart

temporal view x x x x ¸data view ¸ ? x ? x

process view x ¸ ¸ ? ¸the entire column had to be correct for you to get the mark¸ means you must choose this? not the best answer (no marks deducted if you chose this)x means it is not correct


20. The diagram on the left was produced after a couple of meetings with a client who wants aweb-based customer relationship management system for a company that rents videos, games andmusic to customers. The diagram is not complete. Further meetings with the client are needed.

Part I Answer the following questions about the diagram. Write the answers after each question. [5]

What is the name/type of this diagram? _______level 0 dataflow diagram_______

Is the entity "Entertainment Tracker" a person, organization or system? Explain.(1) Could be a person because approval is given to process 1.0. Could be a system because sales/rental history is given to process 10.0 In other words, we don't know.(2) We don't care because this is a logical, not a physical diagram.

Is "5.0 Enter New Comment" a primitive process? Explain.It's a simple process (just add one thing to one data store) and there is probably no need to break itdown further. But there could be a sub process to access inventory.We have to see the hierarchy chart to be sure whether or not it's a primitive. This diagram doesn'ttell you.

In the above two, you had to indicate that there was uncertainty in order to get full marks.

Part II In the examination booklet, draw the context level diagram for the system. [4] To save time, number the data flows on the diagram on the left, and just put the numbers into your context diagram. Label everything else properly.

No new information is needed for this diagram.


Part III In the examination booklet, draw a lower level diagram for "7.0 Process New Product Request". [6] Use the following new/changed information in your diagram.

a) At any time, customers can request a product and the availability of the product is displayedto the customer. If the product is not available it is added to a list of outstanding requests.

b) Once a day, an employee looks at requested products that were not available to customers.c) If the product is available now, the employee sends an email to the customer to tell him/her

that it's now available and that product is taken off the list of outstanding requests.


Part IV In the examination booklet, draw a hierarchy chart for the customer relationship management [5] system. Use the following information in your diagram. Also include information given in points a) b) and c) in part III.

d) The client likes to think of inquiries, history, and picks and comments as three distinct groupsof functionality. Picks and comments belong together.

e) The client will decide later how extracting data and processing rental extension requests are tobe grouped.

If you change the number from that given on the original diagram on the previous page, pleasewrite the original process number below or to the side of each process.

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