System Development Tasks. Systems Analysis & Design Issues. Systems Analysis & Design. MGIS SAD Notes 1

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1 Systems Analysis & Design Issues OBJECTIVES: After studying the material in Ch. 11 and 12, as well as the material in the next two lectures, you should be able to discuss: Systems Analysis & Design SDLC, System Components, Cost/Benefit Analysis, Logical vs. Physical Design, Process vs. Data Design Alternatives to Trad l Systems Development Prototyping, User Development, Buy Package Make vs. Buy Issues Helpful Tools Used in SA & D Skill Requirements for Systems Analysts 1 Systems Analysis & Design What is it? Formal methodologies which are based upon:» formal modeling techniques to describe systems» a distinction between logical & physical design» a structured methodology for moving from a description of user needs to a working system. 2 System Development Tasks Problem Definition Feasibility Analysis Requirements Analysis Logical Design Physical Design Acquire Hardware & Software Coding & Testing Training Conversion Post-audit evaluation Maintenance SDLC PHASES Planning Analysis Design Implementation Support In the Traditional SDLC, these steps are followed in order. MGIS SAD Notes 1

2 System Components» Objectives & Constraints Feedback/Control Input Processing Output Store 4 Economic Feasibility Study: Includes Cost/Benefit Analysis 2 common ways analysts measure the cost & benefits of a system:» Numeric Analysis» Descriptive Analysis What are potential intangible benefits of a system & how would you place a value on them? 5 Logical vs. Physical Design Conceptual view vs. physical components view Examples: building a house Architectural rendering vs. blueprints 6 MGIS SAD Notes 2

3 Systems Analysis Exercise Design a system for producing a bank statement.» Use English-like statements to describe each step. (Each step should begin a new line.) For example: SUBTRACT TRANSACTION AMOUNT FROM BALANCE Use IF statements: IF TRANSACTION IS A CHECK... Use statements like: GET NEXT TRANSACTION PRINT ENDING BALANCE:, BALANCE» The next slide shows sample data 7 Balancing a Checkbook Balance as of 01/01/99: $ Transactions: TYPE PAYEE DATE AMOUNT CHK Safeway 01/03/ CHK DUMP Apts 01/02/ CHK City of Calgary 11/02/ CHK Shaw Cable 03/02/ CHK MGIS Professor 09/01/ CHK U of C Bookstore 10/04/ CHK DUMP Apts 01/03/ CHK Brentwood Liquor 01/03/ CHK DUMP Apts 01/04/ DEP P.S. Student 09/01/ DEP P.S. Student 01/02/ DEP P.S. Student 01/03/ RULES: If balance drops below 0.00, service charge = $50.00 If balance drops below $1,000.00, then SC =.50 per transaction 8 Process vs. Data Design 9 MGIS SAD Notes 3

4 Alternatives to the Traditional SDLC Prototyping End User Computing Purchase software» Alter purchased software Hire consultants and/or contractors 10 Prototyping Users try out parts of proposed system in order to minimize the need for changes when the entire system is implemented. Why is users role in evaluating prototype critical? 11 End User Computing Would you feel comfortable developing a system to track customers or perform billing? Why or why not? 12 MGIS SAD Notes 4

5 Advantages of Off-the-shelf Software rapid implementation some risk avoidance overall cost is usually lower cost and quality are known in advance training costs may be lower others to share experience less need for analysts and programmers immediately useable on acquisition widely tested well documented with numerous support features 13 Disadvantages of Off-the-shelf Software application may be inappropriate» square peg into a round hole likely to meet most, but not all, of a user s requirements application may not interface well with existing applications customization may be difficult additional hardware and software upgrades may be required little control over addition of new features or direction vendor take software After acquisition, user is dependent on outside support (e.g., telephone hot lines) rather than having programmers available if modifications are needed or problems arise 14 Advantages of Custom Software PROS: Specifically designed to satisfy individual user needs More easily modified if the need arises Developers readily available to support implementation and modification if needed CONS: More expensive to develop and maintain because costs are not shared among many users Takes more time to implement 15 MGIS SAD Notes 5

6 OJ Economics FACTS:» A 25lb. bag of oranges cost $6.00 at the fruit stand» 6 oranges make 16 oz of juice» 1 gallon is equal to 128 oz (US)» A 1/2 gallon carton of o.j. costs $2.50 at the store» A 25lb bag of oranges contains 60 oranges Question: Is it cheaper to buy a carton of o.j. or to buy fresh oranges and make orange juice? If you disagree with the problem formulation because you feel the given objective (cost minimization) is too narrow or you need other facts, discuss exactly what those shortcomings are. 16 Occasionally, organizations hire outside consultants to find sources of commercial application software or to develop the software for the organization. Although some organizations feel these consultants have saved them considerable money, others insist they would have been better off not hiring a consultant. What do you see as the advantages or disadvantages of each approach? Factors to consider when selecting development methodology... Impact:» low -- consider user development» high - need IS professional involvement Size:» large -- need controls & IS professional involvement Commonality:» high - look for a package» low - custom development Structure» high - tradition sys development method» low - need prototyping Users experience & Developers familiarity & proficiency with technology / type of application» can off-set or exacerbate previous issues 18 MGIS SAD Notes 6

7 Systems Analysis & Design: Summary Formal methodologies for developing systems help overcome many potential problems inherent in the process of creating of complex systems. Different approaches are suitable for different types of systems and contexts. No matter which methodology chosen, there are several tools that help with the design process and significantly aid communication» these tools are the subject of the next lecture Systems Analysis & Design End Part 2 Read Chap 12 for next time MGIS SAD Notes 7