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UNIVERSITY OF TORONTO
Scarborough College
CSCC40 Analysis and Design of Information Systems
final test answers
Duration: 2 hours. One 8.5 by 11 aid sheet is permitted.
INSTRUCTIONS:
- Check this examination paper. There are 8 pages including this cover page.
- Print your name and student number on this examination paper and your examination booklet.
- Answer all section A questions on this examination paper.
- Answer all section B and C questions in the examination booklet.
- Note that the mark for each question is given in the right-hand column.
- The total number of marks is 87, but this test is worth 25% of your final grade.
For many of the questions, not all possible correct answers are listed –the answers given are representative.
Section A Answer these questions in this examination paper.
A1 Indicate whether the following statements are true or false. [10]
Provide an explanation if you wish.
true Generalization can be used for use cases, actors and classes.
see pages 140 and 218 of the text
false Open architecture allows transfer of control only between adjacent partitions.
see page 326
false Closed architecture is less portable than open architecture.
closed architecture affords easier replacement of the layers that are specific to the platform
false A complete and detailed set of collaboration and sequence diagrams will include all possible operations and
mention all attributes for all classes. not all attributes are parameters in operations
true Activity diagrams can be used to express the logic of an operation.
see page 263
true In UML, objects are used to model the application domain and can therefore model both the human activity and
the application software. modelling may include in a class, objects that are not implemented for reasons such as “this happens so seldom, we will handle it manually” or “this will/may change often”
true A contract is a black box description of a service (of a class or subsystem) that specifies the results of the service
and the conditions under which it will be provided. see page 253
false The current state of an object is fully described by the instance values of it’s attributes.
some change events and elapsed-time events won’t alter an object’s attributes but will cause the object to be in a different state
true The duration of a state is normally dependent upon external events in the application environment.
see pages 274-
false Multiple inheritance means that a super class has more than one subclass.
multiple inheritance means that a subclass has more than one super class
A2 Indicate whether or not the diagram displays the information described in the first column. [5]
displayed information
use case activity
class/ object
collabo- ration sequence statechart
system users Y Y N Y Y N
sequence of operations N Y N Y Y
guard conditions Y N Y Y Y
logic of operations N Y N N N N
static view of the system Y N Y N N
Y = info is displayed, N = info in not displayed, blank = could be answered either way
A3 Give one specific example where encapsulation is helpful in each of the analysis and design phases. [4]
Explain why and how it’s helpful. how encapsulation is helpful
analysis phase
q concentrate on requirements and ignore implementation details q define requirements at the contract level q gain better understanding and communication of requirements and scope of the system
design phase
q draw overview/high level designs to represent the more detailed ones q designers (and programmers) can work on sections of the system q encourages low coupling and high cohesion, good interfaces q final system will be easier to maintain
the biggest mistake made in this question was to not distinguish between analysis and design activities
A4 How can use case diagrams be used in two different phases of a project? [2]
project phase how a use case diagram is used analysis q record and validate requirements
design q remind designers of each actor’s total interface requirements
construction q programmer is aware of each actor’s (user’s) boundaries and actions
testing q test cases must be designed for all use cases and all their options
installation q be aware of who needs to be trained, who will be involved
A5 If you were redesigning the ROSI system, give examples of classes you might define [2]
for any two of the following three item types: concept, event, behaviour item type example of a possible class concept q e.g. registration, grading, graduate student (these often result in generalizations, compositions, associations...)
event q e.g. register in a course, graduate (displaying information to users is not an event because nothing changes)
behaviour q e.g. decline course admission, determine student status (this is something the system (not the user) does)
q defining the term is not the same as giving an example! q check slide # 2 in “classes and objects” –your answers had to be different from what you would have given for the other types
A9 If you were to replace the ROSI system, what implementation method or methods would [5]
you use to install the new system? Explain why. Also explain why you would not use each of the others. For most cases, either yes or not could have been defended. The points under the reason column are items that could have been considered. recommend? Y/N reason
direct
q there are low activity periods in ROSI when a direct installation would be not quite as risky q (interestingly, some students said ROSI was large and other said small!)
parallel
q it’s unlikely for all students to bother with entering data in both old and new, thereby making comparison between them problematic
phased
q ROSI does have subsystems (many of you mentioned them) and these could be installed separately
pilot
q if you consider the ROSI system as occupying one site this is not an option, but if you think of the users (they occupy several campuses, they are undergrads, grads, non-credit students) as occupying different virtual sites, you could argue the pilot method q but there are problems with students taking courses on more than one campus, etc.
day-one
q many mentioned that it would take years for a students to graduate and leave, and any one student’s records can’t easily be on two separate systems anyway q you lost up to 2 marks if your explanations were not specific to ROSI (i.e. general features of the method were not adequate answers) q you lost marks if your answers demonstrated that you didn’t understand the installation methods.
Section B Answer these questions in the examination booklet.
The next three questions are related to each other and must be done in order.
Depending on how you approach these questions, you may or may not need to make some assumption if you need more information. Please document any assumption you make.
B1 Shown on the previous page is an incomplete class diagram. Use the classes shown plus the [5]
additional information below, to draw the class diagram in your examination booklet. Note that it may still be incomplete, but will be sufficient for you to answer questions B2 and B3.
Section C Answer these questions in the examination booklet.
The next four questions are related to each other and must be done in order because
your answers depend on your decisions in previous questions.
Before you start, read all the use cases carefully.
Use case #1: apply for a credit card q a customer fills out an application form and sends it to a bank q the bank completes a credit check and if the customer’s credit is not acceptable, returns the application with an explanation q if the application is accepted, the bank mails the customer two separate items (in two separate envelopes): o the credit card itself o the customer’s personal identification number (PIN) q when the customer has received both, he activates the card by making a phone call
Use case #2: use a credit card q a customer hands the merchant his credit card q the merchant scans the card and the merchant’s computer sends the card information to the bank q the bank checks the customer’s card status and responds with either a rejection or an authorization number q if the card was rejected by the bank, the merchant just returns the card to the customer q if an authorization number is given by the bank, the merchant produces an authorization slip and a receipt and gives both to the customer q the customer signs the authorization slip and returns it to the merchant
Use case #3: credit card billing q the merchant notifies the bank of the purchase q the bank produces a statement showing all purchases made and sends the statement to the card holder (customer) q if the card holder pays the bank at least the minimum payment amount on time, then the card remains active q if the card holder does not pay for 2 months or pays less than the minimum payment amount, the card is put on hold q if the card is on hold and the customer pays all outstanding minimum payments, the card is reactivated q if the card has been on hold for more than 6 months, the card is cancelled
Depending on how you approach these questions, you may or may not need to make some assumption if you need more information. Please document any assumption you make.
C1 Draw an activity diagram for the second use case (use a credit card) described above. [5]
Do not draw activity diagrams for the other use cases! The answer diagram in the accompanying PDF file. It was also somewhat reasonable in this situation to include the merchant’s computer in a swim lane. But if you did so, you had to make it participate in all control flows between the merchant and the bank!
C2 Draw a use case diagram showing all the above use cases. [5]
This question was poorly worded. Some answered with a general use case and others with a detailed use case. They were marked as follows... criteria general diagram detailed diagram marks all three actors are shown and correctly labelled
had to be shown just once could be shown in more than one place or diagram
1 mark
the lines were connected to the right use cases
connected to all the correct use cases
most of the connections were OK
1 mark
use cases were correctly drawn and labelled
correct wording in all cases most of the wording was OK
1 mark
system boundary was shown
correct and labelled same 1 mark
diagram easy to read very neat mostly legible 1 mark added value (extends, uses, generalizations etc) used and with few errors up to 2 bonus marks Students who chose to do the detailed diagram could have received up to 2 bonus marks. This is to compensate for the time spent on this question that was not spent on other questions and possibly causing a loss of marks in those other questions. No marks were deducted if the added value items were incorrect because there is no proof that students who chose the general could have done these items correctly.
C3 Draw a statechart diagram for the credit card. Refer to all the above use cases. [10]
The answer diagram is in the accompanying PDF file.
C4 Document one of the use cases you drew in question C2. [5]
Select the most complex use case. Use point form text –do not write long passages.
To document a use case, you supply the following information: q name of use case q description of purpose (this is purpose for users, in user terminology) q trigger q pre-conditions q post-conditions q actors q stakeholders q relationships to other use cases q logic flow q alternate flows If a use case has alternate flows, then the post-conditions should also indicate alternates.
