© Prentice Hall CHAPTER 9 Application Development by Information Systems Professionals

© Prentice Hall SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC) DEFINITION PHASE: DEFINITION PHASE: –Feasibility analysis –Requirement definition CONSTRUCTION PHASE: CONSTRUCTION PHASE: –System design –System building –System testing IMPLEMENTATION PHASE: IMPLEMENTATION PHASE: –Installation –Operations –Maintenance*

© Prentice Hall DEFINITION PHASE FEASIBILITY ANALYSIS: Thorough analysis by team (leader, systems analysts, end-users). Economic, operational, technical FEASIBILITY ANALYSIS: Thorough analysis by team (leader, systems analysts, end-users). Economic, operational, technical REQUIREMENTS DEFINITION: If feasibility report approved, team develops logical design: processes, data flow & relationships. Result is system requirements document REQUIREMENTS DEFINITION: If feasibility report approved, team develops logical design: processes, data flow & relationships. Result is system requirements document*

© Prentice Hall CONSTRUCTION PHASE SYSTEM DESIGN: Detailed design of physical system based on requirements document. Details of hardware, software, databases, modules, interrelationships for quality system (accurate, reliable, auditable, robust, changeable, secure, efficient, user friendly, flexible, well documented) SYSTEM DESIGN: Detailed design of physical system based on requirements document. Details of hardware, software, databases, modules, interrelationships for quality system (accurate, reliable, auditable, robust, changeable, secure, efficient, user friendly, flexible, well documented)*

© Prentice Hall CONSTRUCTION PHASE SYSTEM BUILDING: IS specialists produce programs, databases. End-users answer questions, interpret requirements, help design documents SYSTEM BUILDING: IS specialists produce programs, databases. End-users answer questions, interpret requirements, help design documents SYSTEM TESTING: By module, subsystem, entire system to find & correct problems. Users acceptance test SYSTEM TESTING: By module, subsystem, entire system to find & correct problems. Users acceptance test DOCUMENTATION DOCUMENTATION*

© Prentice Hall IMPLEMENTATION PHASE INSTALLATION: Four strategies INSTALLATION: Four strategies –Parallel: Run old & new systems for awhile to check validity. Safe –Pilot: Install in one part of organization at a time. Learn and adapt –Phased: In large system change one function at a time (e.g., order entry) –Cutover: Start using entire system. Can be dangerous if errors exist*

© Prentice Hall IMPLEMENTATION PHASE OPERATIONS: Training, documentation, people and computers must work well together. Project team disbanded OPERATIONS: Training, documentation, people and computers must work well together. Project team disbanded MAINTENANCE: Operations stage of life cycle. Correct errors as discovered, update as needed, monitor activities and output. Be aware of gap between organization’s needs and system’s performance MAINTENANCE: Operations stage of life cycle. Correct errors as discovered, update as needed, monitor activities and output. Be aware of gap between organization’s needs and system’s performance*

© Prentice Hall COST OF ERROR CORRECTION 1. REQUIREMENTS4. DEVELOPMENT TEST 2. DESIGN5. ACCEPTANCE TEST 3. CODE6. OPERATION

© Prentice Hall SDLC ROLES PROJECT MANAGER: Must have IS skills, plans project, uses project management tools, builds project team PROJECT MANAGER: Must have IS skills, plans project, uses project management tools, builds project team SYSTEMS ANALYST: IS professional changes business problem into IS solution SYSTEMS ANALYST: IS professional changes business problem into IS solution END-USER: Functional representative provides needs, judges results END-USER: Functional representative provides needs, judges results SPONSORS, CHAMPIONS: Will be addressed in Chapter 12 SPONSORS, CHAMPIONS: Will be addressed in Chapter 12*

© Prentice Hall SDLC CHARACTERISTICS MANAGEABLE PROJECT SIZE: Break into independent pieces. Stay within budget & other constraints MANAGEABLE PROJECT SIZE: Break into independent pieces. Stay within budget & other constraints ACCURATE REQUIREMENTS DEFINITION: Extraneous specifications lead to added expense, extends completion ACCURATE REQUIREMENTS DEFINITION: Extraneous specifications lead to added expense, extends completion EXECUTIVE SPONSORSHIP: Sponsor with responsibility and resources critical to success EXECUTIVE SPONSORSHIP: Sponsor with responsibility and resources critical to success*

© Prentice Hall SDLC ADVANTAGES HIGHLY STRUCTURED, SYSTEMATIC PROCESS HIGHLY STRUCTURED, SYSTEMATIC PROCESS THOROUGH DEFINITION REQUIREMENTS THOROUGH DEFINITION REQUIREMENTS CLEAR MILESTONES WITH MANAGEMENT SIGN-OFFS CLEAR MILESTONES WITH MANAGEMENT SIGN-OFFS*

© Prentice Hall SDLC DISADVANTAGES MAY IGNORE EVOLVING REQUIREMENTS DURING PROJECT MAY IGNORE EVOLVING REQUIREMENTS DURING PROJECT TIME-CONSUMING, COSTLY PROCESS TIME-CONSUMING, COSTLY PROCESS TOP-DOWN COMMITMENT REQUIRED TOP-DOWN COMMITMENT REQUIRED*

© Prentice Hall PROTOTYPING LIFE CYCLE 1.IDENTIFY REQUIREMENTS 2.DEVELOP INITIAL PROTOTYPE 3.USE PROTOTYPE, NOTE CHANGES 4.REVISE, ENHANCE PROTOTYPE: Return to Step 3 as needed 5.EVALUATE OPERATIONAL SYSTEM 6.MAKE CHANGES OR ABANDON 7.INSTALL, OPERATE, MAINTAIN *

© Prentice Hall COMBINING PROTOTYPING & SDLC PROTOTYPING/PILOTING PHASE: PROTOTYPING/PILOTING PHASE: –DETERMINE BASIC REQUIREMENTS –PROTOTYPE SYSTEM –PILOT PROTOTYPE SDLC CONSTRUCTION PHASE: SDLC CONSTRUCTION PHASE: –SYSTEM BUILDING –SYSTEM TESTING SDLC IMPLEMENTATION PHASE: SDLC IMPLEMENTATION PHASE: –INSTALLATION –OPERATIONS –MAINTENANCE*

© Prentice Hall JOINT APPLICATION DESIGN (JAD) TECHNIQUE INVOLVING TEAM OF USERS, IS SPECIALISTS TECHNIQUE INVOLVING TEAM OF USERS, IS SPECIALISTS INTENSE, STRUCTURED PROCESS INTENSE, STRUCTURED PROCESS DEVELOP REQUIREMENTS OR REVIEW DESIGN PROPOSAL DEVELOP REQUIREMENTS OR REVIEW DESIGN PROPOSAL CAN LAST HOURS, DAYS, OFTEN AT LOCATION REMOVED FROM WORKPLACE CAN LAST HOURS, DAYS, OFTEN AT LOCATION REMOVED FROM WORKPLACE*

© Prentice Hall COMPUTER-AIDED SOFTWARE ENGINEERING (CASE) COLLECTION OF SOFTWARE TOOLS TO AUTOMATE SDLC PROCESSES: DIAGRAMMING TOOLS DIAGRAMMING TOOLS COMPUTER DISPLAY, REPORT GENERATORS COMPUTER DISPLAY, REPORT GENERATORS ANALYSIS TOOLS ANALYSIS TOOLS CENTRAL REPOSITORY CENTRAL REPOSITORY DOCUMENTATION GENERATORS DOCUMENTATION GENERATORS CODE GENERATORS CODE GENERATORS*

© Prentice Hall RAPID APPLICATION DEVELOPMENT (RAD) HYBRID OF SDLC, PROTOTYPING, JAD, CASE HYBRID OF SDLC, PROTOTYPING, JAD, CASE PRODUCE SYSTEM IN 6 MONTHS OR LESS PRODUCE SYSTEM IN 6 MONTHS OR LESS STEPS: STEPS: –PLANNING –USER DESIGN –CONSTRUCTION –IMPLEMENTATION (CUTOVER)*

© Prentice Hall RAD ADVANTAGES DRAMATIC SAVING IN TIME DRAMATIC SAVING IN TIME FOCUSES ON ESSENTIAL SYSTEM REQUIREMENTS FOCUSES ON ESSENTIAL SYSTEM REQUIREMENTS ABILITY RAPIDLY TO CHANGE SYSTEM DESIGN AT USER’S REQUEST ABILITY RAPIDLY TO CHANGE SYSTEM DESIGN AT USER’S REQUEST*

© Prentice Hall RAD DISADVANTAGES QUALITY MAY BE SACRIFICED FOR SPEED QUALITY MAY BE SACRIFICED FOR SPEED TIME CONSUMING FOR KEY PERSONNEL TIME CONSUMING FOR KEY PERSONNEL POSSIBLE SHORTCUTS ON INTERNAL STANDARDS, MODULE REUSABILITY POSSIBLE SHORTCUTS ON INTERNAL STANDARDS, MODULE REUSABILITY*

© Prentice Hall OBJECT-ORIENTED METHODS (O-O) HOLD GREAT PROMISE TO PRODUCE BETTER SYSTEMS AT LESS COST HOLD GREAT PROMISE TO PRODUCE BETTER SYSTEMS AT LESS COST OBJECTS HIGHLY COHESIVE, LOOSELY COUPLED, REUSABLE OBJECTS HIGHLY COHESIVE, LOOSELY COUPLED, REUSABLE CAN REDUCE ERRORS, IMPROVE MAINTENANCE CAN REDUCE ERRORS, IMPROVE MAINTENANCE*

© Prentice Hall CHAPTER 9 Application Development by Information Systems Professionals