CSCC40 Analysis and Design of Information Systems mid-term exam

Transcription

1 UNIVERSITY OF TORONTO at Scarborough CSCC40 Analysis and Design of Information Systems mid-term exam October Duration: 2.5 hours One 8.5 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. A1. Indicate whether the following statements are or. [15] True False The functional requirement, "ease of use", is an emergent property. [Ease of use depends on many things such as response time, good feedback, etc.] "Value chain" is a chain of activities. Products pass all activities in the chain in order, and at each activity the product gains some value. [see course lecture slides] CASE tools check models for consistency, completeness, syntactical correctness and relevance to user requirements. [The design can be perfect in technique etc. but if the requirements are not correct, the design reflects the garbage-in-garbage-out syndrome.] Configuration management will help track the network components, but you need some other method to track application software components. [Configuration management is about software components as well: source code, documentation, test cases, etc.] During a project, rework is almost inevitable because inadequacies in the requirements analysis may not become evident until subsequent phases. [see the V model] Evolutionary prototyping is recommended for systems that handle large volumes of data. [Large volumes of data require a large amount of overhead design that you would never invest in a prototype, especially at the beginning. ] When considering system options, ROI and payback period calculations will either both be favourable or unfavourable for any one option. [Whether or not they are favourable depends on the financial situation of the system users. Not all users have the same financial concerns. ] How you store data will not affect the user interface. [Your data storage decisions affect response time. Response time is definitely an important consideration for user interfaces.] Process-oriented development means you are not designing the data specifically for the application. [In data oriented design, you design data to model the business and the design is for all applications, not just one specific application. ] Requirements traceability is an aspect of system auditability. [Auditability means you can trace a requirement through the analysis, design, programming and the results produced when the system is running.] The spiral methodology includes a repeating cycle of planning, risk analysis, engineering and evaluation throughout the project. [That's the definition of spiral methodology! ] Transaction processing systems are the source of data for management support systems. [Management makes its decisions based on the past experience (transactions stored to date) plus future projections. ] When auditors want to see documented validation of requirements, you should not use prototyping as your methodology. [You can validate and document validation results when prototyping, and again after the prototype is approved.] CSCC40 mid-term exam Fall 2007 Page 1 / 10

2 When many users are making the same mistake, the best solution is training. [The system needs to be fixed. The same mistake means that somehow the system leads users to make that mistake.] You can use either the waterfall or the spiral methodology when performing either structured or object-oriented analysis and design techniques. [The techniques and the methodologies are both flexible enough.] A2. Which of the following statements about information systems strategy is not? [1] a. It informs the business strategy of ways that IT can help. b. It drives the information technology strategy by defining technical requirements. c. Its goals are set by the business strategy. d. It provides the information technology strategy with system requirements. e. It is enabled by the information technology strategy. [While statement b. could be argued if technology is a limiting factor, this is unusual. The information needed by users is not dependent on the available technology, how it's presented/automated does not alter the information.] A3. Describe or give an example of "feed-back" and of "feed-forward" as methods of system control. [2] feed-back ["...is a process whereby some proportion of the output signal [or calculated/derived results] is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system." Wikipedia] feed-forward ["...is a term describing a kind of system that reacts to changes in it's environment, usually to maintain some desired state of the system" Wikipedia] A4. What is the difference between decision support systems and expert systems? [2] [decision support systems come in many flavours: expert system, domain modeling systems, etc. they can include working with non-structured problems expert systems contain subject-specific knowledge, rules and an inference engine to answer questions; i.e. structured problems] A5. Systems development can be viewed from three perspectives: technological, social and professional. [2] What is meant by the professional perspective? [any two of: ethics, practices (e.g. methodologies), standards, laws, policies, quality practices] A6. Consider a system for a lending library. Give an example for each of the following types of system request. [3] better performance [returning materials takes less than 3 seconds per item query results are available in less than 2 seconds] more information [The system must allow up to 20 material classifications. (classification = book, periodical, CD...)] stronger controls [unable to renew books till all fees are paid added security... this was the most difficult of the three statement of standard functionality is not additional control] CSCC40 mid-term exam Fall 2007 Page 2 / 10

3 A7. When choosing what project to undertake next, you identify, classify and rank the projects before [6] making the selection. Give 6 different considerations other than urgency and feasibility. [any 6 of: size of project strategic impact cost/benefit ratio or ROI or payback resource availability competitive edge value chain impact organizational impact technological challenge there were some other lists that may have received some marks] A8. For each of the following statements about feasibility, circle "True" or "False" [4] and give an example to support your decision. Note that some (but not all) statements could be in some circumstances and in other circumstances. [if you just circled True of False without and example, you received very few marks... in general this was marked based on your demonstrated understanding of the issues] True or False? True or False? True or False? True or False? If the ROI is very low, the project does not have economic feasibility. [feasible means it can be done, and does not necessarily mean it should be done, so you could have commented either way] The client's competition is using some new technology but your team has no experience with it. Therefore the project is not technically feasible if the client insists on this technology. [again this could go either way... you could argue that if you bring in experts or provide training, it becomes feasible] All parties agree that the documentation and training materials are useful and user friendly. The project is therefore operationally feasible. [good documentation etc does not fix a buggy or irrelevant system, but poor documentation etc. could make a good system in feasible] Your development team plans to use extreme programming for the project, but the data management group insist on following a serial approach (e.g. waterfall methodology). This project is not politically feasible. [politics is about social relations involving authority or power... so to say it's politically feasible you have to prove that the problem can and will be resolved] A9. Answer the following questions for the PERT chart below. [3] What are the tasks on the critical path? [ A B E F H J ] How much float does task H have? [ 1 day ] CSCC40 mid-term exam Fall 2007 Page 3 / 10

4 A10. When we have estimated a project's costs and benefits, we can determine the benefit to cost ratio, [2] the ROI, and the payback period. Given that the benefit to cost ratio is favourable, why would we still want to calculate the ROI and the payback period? ROI [ there is another project that will give a better ROI ] payback period [cannot afford the owe that money until payback time] A11. If you were shown only the data architecture of a corporation's computer systems, could you [2] figure out if the systems' development was process oriented or data oriented? Explain. [ yes...process-oriented is unlikely to result in a good corporate data model, so if you look at the data architecture and find that there is duplication of information and/or the data tables are not normalized or... then you know systems were developed in a process-oriented manner] A12. Prototyping is useful during the analysis and design phases if users are involved in the [3] evolution of the prototype. There are however some disadvantages to prototyping. Describe three disadvantages or risks. [see course slides and text book] A13. The spiral model for incremental development has four repeated phases. Name them, [2] or describe the deliverable for each phase [planning risk assessment development evaluation all 4 and in the right requence] A14. After you have identified some of the requirements for a system, you need to check that your [2] understanding is correct. Describe two ways in which you could do this. any two of: requirements review by stakeholders prototyping model validation formal methods acceptance test planning CSCC40 mid-term exam Fall 2007 Page 4 / 10

5 A15. Why do you need strict requirements tracing? [1] - for audit purposes need to know the source of all requirements need to be sure requirements are not forgotten or accidentally altered - or to prevent gold-plating A16. Listed below are two requirements identified in an early planning meeting. [2] For each, what question(s) should you should ask in a subsequent meeting in order to make sure the requirements are clear and can be checked in acceptance tests? [looking for quantifiable requirements in this question] The system must be fast. [how fast specific response time... etc. ] It must be easy to use. [what is the maximum training period? what is the expected user error rate? etc. ] A17. The V model describes the phases of systems development and maps them against time and [2] the level of abstraction. What does the V model tell us? [You can't find bugs until you are testing at the same level of abstraction. Many mistakes in initial requirements will not become evident until the system is in production.] A18. Match the interface design quality characteristic with the examples. [3] forcing D affordance B auto learning A or F feedback E mapping A or F mental model C a. the screen layout is the same as the input form being keyed from b. all options are visible on the screen c. folder contents display is hierarchical d. when the user selects a function, the icons for irrelevant options disappear e. when a transaction is accepted and stored, the transaction ID is assigned and displayed f. the help icon is always on the top right-hand corner of the screen. A19 Requirements can be classified. For each requirement in the first column [4] select only one of the two classifications in the next two columns. The customer inquiry responses must take less than 2 sec. r functional r non-functional Order entry and all order maintenance needs a full audit trail. r specific task r emergent property User training on the working system will take less than 10 days. r product r process In 5 years the system is expected to handle 400 orders per day. r volatile r stable CSCC40 mid-term exam Fall 2007 Page 5 / 10

6 Section B The remainder of this exam is based on the descriptions below. Use the exam booklet to answer the questions in section B. You are the senior analyst and designer for a new materials management system for a manufacturing company that manufactures and sells widgets. The hierarchy diagram below gives you an overview of most of the company's systems. the new system In a meeting with users you learn the following: Plan materials requirements...the engineers figure out what materials are needed and how much is needed to manufacture the widgets; they check the inventory and the plant manufacturing schedule (owned by the "plan production" system) to see how much needs to be purchased and when; this information is stored in a data store Purchase materials...the purchasing department takes the results of the engineers' calculations and purchases the material from suppliers; the purchasing department is responsible for keeping supplier information and for creating purchase orders Receive materials...when the materials arrive, warehouse staff compare what has arrived with the purchase orders to see if there are overs or shorts, then the warehouse staff update the purchase orders to indicate what actually arrived; at the same time, they update the inventory Control inventory... once a year the warehouse staff count the materials and make any corrections to the inventory figures (after they check the warehouse, they have a hand-written list of materials and the quantities they found, they compare these figures to the inventory figures and make any corrections) Perform quality assurance...the engineers also check the materials in inventory as part of their quality assurance responsibilities and they remove any defective materials; when they remove materials they also update the inventory figures Information about suppliers, materials, inventory figures, purchase orders, and materials to be purchased are to be part of this material management system. Materials may be stored in more than one location, so inventory numbers will not be kept with material descriptive information. CSCC40 mid-term exam Fall 2007 Page 6 / 10

7 You asked to see copies of the purchase orders. They contain the following information: purchase order number supplier ID supplier name supplier address date needed for each item ordered: material ID unit price quantity needed cost (price * quantity) discount expected (percentage) shipping instructions sales tax rate total cost (for all materials) total discount (for all materials) sales tax amount final amount (= total cost - discount + tax) You asked questions about the purchase orders and made the following notes: purchase order numbers are unique for each new purchase order the supplier name and address are stored in the supplier data store the unit price is the same for any supplier (it is a standard price) the discount is for each item and is based on previous purchases; it's a volume discount that the purchasing department calculates separately for each purchase order shipping instructions can vary with each order the sales tax rate is based on the supplier's country and also stored in the supplier data store you do not need to store any calculated fields because they can be derived (calculated) when the purchase order is printed or displayed B1. Draw a context diagram for the manage materials system. [8] [you didn't need to include the supplier because it was not specifically mentioned above] CSCC40 mid-term exam Fall 2007 Page 7 / 10

8 B2. Draw an ERD for the entities for which you will have data stores. [5] Indicate primary keys, foreign keys and non-key elements. Do not include elements (variables) not mentioned in the purchase order description unless the elements are needed to ensure third normal form. [you had two ways of including inventory (1) as a separate entity (2) as an on hand figure in the material entity] data store purchase order (PO) PO detail Supplier Material primary key = bold foreign key = * non key PO number supplier ID * date needed shipping instructions PO number material ID * quantity needed discount % supplier ID supplier name supplier address sales tax rate material ID unit price on hand B3. Draw a DFD for the five materials management processes. [10] Label the entities, processes and data stores. In this diagram, do not label the data flows. [Please note that there should be no flows between entities and data stores, or between entities and entities. Also the twoheaded arrow is only used between a process and a data store if the process is updating the data store. If there is a data flow from an entity to a process and another data flow from that process back to the entities, then it's two arrows, not one twoheaded arrow between them] CSCC40 mid-term exam Fall 2007 Page 8 / 10

9 B4. Document the plan materials requirement process. [6] For the logic, just include a decision table to illustrate the following: If there are no future orders and the "on hand" (OH) is less than "target quantity" (TQ) then order the difference between "target quantity" (TQ) and "on hand" (OH). If there are future orders and the "on hand" (OH) is less than the "target quantity" (TQ) plus the quantity needed for the future orders (FO), then order the difference between ("target quantity" (TQ)+ quantity needed for future orders (FO)) and "on hand" (OH). If none of the above are, then no order is needed. [2 marks for documentation and 4 for the decision table see the lecture slides for data dictionary to see what you could include] there are future orders Y Y N N on hand < target quantity - - Y N on hand < target quantity + future orders Y N - - order ((target quantity + future orders) - on hand ) X order (target quantity - on hand) X place no order X X CSCC40 mid-term exam Fall 2007 Page 9 / 10

10 B5. Draw a CRUD matrix for your system. [5] [the CRUD matrix is for process VS data store... no other combination makes sense!] inventory to purchase purchase orders purchase order suppliers materials plan material requirements R C perform quality assurance U purchase materials R C C R/U R receive materials U R R control inventory U B6. Draw a dialogue structure chart for the control inventory process. [5] [Since there are several ways to map dialogue, the marking was based on the following considerations: - only actions and decision are shown, in the right sequence - no data stores or entities should be represented - since there are several materials in inventory, you should show repetition] CSCC40 mid-term exam Fall 2007 Page 10 / 10