System lifecycle

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System lifecycle

  1. 1. 12.1 12. APPROACHES TO SYSTEMS-BUILDING
  2. 2. CONTENTS <ul><li>TRADITIONAL SYSTEMS LIFECYCLE </li></ul><ul><li>ALTERNATIVE SYSTEM-BUILDING APPROACHES </li></ul><ul><li>* </li></ul>12.3
  3. 3. SYSTEM LIFECYCLE <ul><li>PROJECT DEFINITION: Is there a problem? Can it be solved with a project? </li></ul><ul><li>SYSTEM STUDY: Analyze problems in existing systems (manual or automated); define objectives; evaluate alternatives </li></ul><ul><li>DESIGN: Logical & physical specifications for systems solution </li></ul><ul><li>PROGRAMMING: Develop software code </li></ul><ul><li>* </li></ul>12.4
  4. 4. SYSTEM LIFECYCLE <ul><li>INSTALLATION: Test, train, convert to new system </li></ul><ul><li>POST-IMPLEMENTATION: On-going evaluation, modifications for improvement to meet new requirements </li></ul><ul><li>NECESSARY FOR LARGE, COMPLEX SYSTEMS & PROJECTS (TPS AND MIS) </li></ul><ul><li>* </li></ul>12.5
  5. 5. SYSTEM LIFECYCLE <ul><li>LIMITATIONS: </li></ul><ul><li>CAN BE COSTLY, TIME CONSUMING, INFLEXIBLE </li></ul><ul><li>MAY ENCOURAGE FREEZING SPECIFICATIONS EARLY IN DEVELOPMENT </li></ul><ul><li>MAY NOT BE SUITABLE FOR DSS OR SMALL, LESS STRUCTURED SYSTEMS </li></ul><ul><li>* </li></ul>12.6
  6. 6. ALTERNATIVE SYSTEM-BUILDING APPROACHES <ul><li>PROTOTYPING </li></ul><ul><li>APPLICATION SOFTWARE PACKAGES </li></ul><ul><li>END-USER DEVELOPMENT </li></ul><ul><li>OUTSOURCING </li></ul><ul><li>* </li></ul>12.7
  7. 7. PROTOTYPING <ul><li>PROCESS OF BUILDING EXPERIMENTAL SYSTEM TO DEMONSTRATE, EVALUATE APPROACH; USERS REFINE NEEDS </li></ul><ul><li>PROTOTYPE: Preliminary working version of information system for demonstration, evaluation purposes </li></ul><ul><li>ITERATIVE PROCESS </li></ul><ul><li>* </li></ul>12.8
  8. 8. STEPS IN PROTOTYPING <ul><li>1. IDENTIFY USER’S REQUIREMENTS </li></ul><ul><li>2. DEVELOP INITIAL PROTOTYPE </li></ul><ul><li>3. USE PROTOTYPE </li></ul><ul><li>4. REVISE & ENHANCE PROTOTYPE </li></ul><ul><li>BEST FOR DESIGN OF END-USER INTERFACE: How end-user interacts with system </li></ul><ul><li>* </li></ul>12.9
  9. 9. APPLICATION SOFTWARE PACKAGES <ul><li>PREWRITTEN, PRECODED APPLICATION SOFTWARE THAT IS COMMERCIALLY AVAILABLE FOR SALE OR LEASE </li></ul><ul><li>GEARED TO COMMON REQUIREMENTS </li></ul><ul><li>* </li></ul>12.10
  10. 10. SELECTED EXAMPLES OF APPLICATION PROGRAMS <ul><li>ACCOUNTS RECEIVABLE; BOND & STOCK MANAGEMENT; COMPUTER-AIDED DESIGN (CAD) ; DOCUMENT IMAGING; E- MAIL; ENTERPRISE . RESOURCE PLANNING (ERP); GROUPWARE; HEALTH CARE; HOTEL . MANAGEMENT; INTERNET TELEPHONE; INVENTORY CONTROL; JOB COSTING; LIBRARY SYSTEMS; LIFE INSURANCE; MAILING LABELS; MATHEMATICAL / STATISTICAL MODELING; ORDER PROCESSING; PAYROLL; PROCESS CONTROL; TAX ACCOUNTING; WEB BROWSER; WORD PROCESSING </li></ul><ul><li>* </li></ul>12.11
  11. 11. CUSTOMIZATION <ul><li>MODIFYING SOFTWARE PACKAGE </li></ul><ul><li>TO MEET ORGANIZATION’S UNIQUE REQUIREMENTS </li></ul><ul><li>WITHOUT DESTROYING INTEGRITY OF PACKAGE </li></ul><ul><li>RAISES DEVELOPMENT COSTS </li></ul><ul><li>MUST WEIGH COSTS / BENEFITS </li></ul><ul><li>* </li></ul>12.12
  12. 12. EFFECTS OF CUSTOMIZING SOFTWARE ON TOTAL IMPLEMENTATION COSTS 12.13 0 2 4 6 8 10 0.5 1 2 3 4 5 % LINES OF CODE CONVERTED TOTAL IMPLEMENTATION COSTS
  13. 13. <ul><li>DESCRIPTION (PRESENT, PROPOSED) </li></ul><ul><li>RELIABILITY </li></ul><ul><li>BACKUP </li></ul><ul><li>SERVICES </li></ul><ul><li>SYSTEM SPECIFICATIONS </li></ul><ul><li>CRITERIA </li></ul><ul><li>DEMONSTRATION (PROTOTYPE) </li></ul><ul><li>SCHEDULE (BENCH MARKS) </li></ul><ul><li>PRICE (PENALTIES) </li></ul><ul><li>SPECIFIC QUESTIONS </li></ul><ul><li>PROCEDURES FOR RESPONSE </li></ul><ul><li>* </li></ul>REQUEST FOR PROPOSAL (RFP ) Source: Senn, Information Technology in Business (1995) 12.14
  14. 14. END-USER DEVELOPMENT <ul><li>END-USERS DEVELOP INFORMATION SYSTEM </li></ul><ul><li>WITH LITTLE HELP FROM </li></ul><ul><li>TECHNICAL SPECIALISTS </li></ul><ul><li>USING 4th GENERATION TOOLS </li></ul><ul><li>* </li></ul>12.15
  15. 15. END-USER DEVELOPMENT <ul><li>STRENGTHS: </li></ul><ul><li>IMPROVED REQUIREMENTS DETERMINATION </li></ul><ul><li>INCREASED USER INVOLVEMENT & SATISFACTION </li></ul><ul><li>REDUCED APPLICATION BACKLOG </li></ul><ul><li>* </li></ul>12.16
  16. 16. END-USER DEVELOPMENT <ul><li>WEAKNESSES: </li></ul><ul><li>RELATIVELY INEFFICIENT </li></ul><ul><li>SLOW TRANSACTION PROCESSING </li></ul><ul><li>MAY CARRY HIGH COST </li></ul><ul><li>LARGE FILES CAN DEGRADE PERFORMANCE </li></ul><ul><li>NONPROCEDURAL APPROACH MAY LIMIT LOGIC & UPDATING REQUIREMENTS </li></ul><ul><li>* </li></ul>12.17
  17. 17. MANAGING END-USER DEVELOPMENT <ul><li>INFORMATION CENTER: </li></ul><ul><li>SPECIAL FACILITY WITHIN ORGANIZATION </li></ul><ul><li>PROVIDES TRAINING, SUPPORT FOR END-USER-COMPUTING </li></ul><ul><li>* </li></ul>12.18
  18. 18. OUTSOURCING <ul><li>CONTRACTING: </li></ul><ul><li>COMPUTER CENTER OPERATIONS </li></ul><ul><li>TELECOMMUNICATIONS NETWORKS </li></ul><ul><li>APPLICATION DEVELOPMENT </li></ul><ul><li>TO EXTERNAL VENDORS </li></ul><ul><li>* </li></ul>12.19
  19. 19. OUTSOURCING <ul><li>WHEN TO OUTSOURCE: </li></ul><ul><li>IF FIRM WON’T DISTINGUISH ITSELF BY DEVELOPING APPLICATION (e.g. Payroll) </li></ul><ul><li>PREDICTABILITY OF UNINTERRUPTED SERVICE NOT IMPORTANT (e.g. travel expense processing) </li></ul><ul><li>* </li></ul>12.20
  20. 20. OUTSOURCING <ul><li>WHEN TO OUTSOURCE: </li></ul><ul><li>IF EXISTING SYSTEM IS LIMITED, INEFFECTIVE, INFERIOR </li></ul><ul><li>TO IMPROVE THE CONTRIBUTION OF IT TO BUSINESS PERFORMANCE </li></ul><ul><li>* </li></ul>12.20
  21. 21. 12.42 12. APPROACHES TO SYSTEMS-BUILDING
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