Appraise system building alternativesAppraise system building alternatives Compare strengths, weaknesses of approachesCompare strengths, weaknesses of approaches Assess solutions to problems created by approachesAssess solutions to problems created by approaches Describe tools, methodologies of systems developmentDescribe tools, methodologies of systems development* Learning Objectives

System Lifecycle Project definition: is there a problem? Can it be solved with a project?Project definition: is there a problem? Can it be solved with a project? System study: analyze problems in existing systems; Define objectives evaluate alternativesSystem study: analyze problems in existing systems; Define objectives evaluate alternatives Design: logical & physical specifications for systems solutionDesign: logical & physical specifications for systems solution Programming: develop software codeProgramming: develop software code*

System Lifecycle Installation: construct, test, train, convert to new systemInstallation: construct, test, train, convert to new system Post-installation: on-going evaluation, modifications for improvement to meet new requirementsPost-installation: on-going evaluation, modifications for improvement to meet new requirements These steps are necessary for large, complex systems & projects These steps are necessary for large, complex systems & projects*

System Lifecycle Can be costly, time consumingCan be costly, time consuming May encourage freezing specifications early in developmentMay encourage freezing specifications early in development May not be suitable for small, less structured systemsMay not be suitable for small, less structured systems*

Alternative System- building Approaches PrototypingPrototyping Application software packagesApplication software packages End-user developmentEnd-user development OutsourcingOutsourcing*

Prototyping Process of building experimental system to demonstrate, evaluate approach; Users refine needs Process of building experimental system to demonstrate, evaluate approach; Users refine needs Prototype: preliminary working version of information system for demonstration, evaluation purposesPrototype: preliminary working version of information system for demonstration, evaluation purposes Iterative processIterative process*

Application Software Packages Prewritten, pre-coded application software, commercially available for sale or lease Prewritten, pre-coded application software, commercially available for sale or lease Geared to common requirements (significant few; Canned functions)Geared to common requirements (significant few; Canned functions) Customization: modification of software to meet organization’s needs (trivial many; Use programming tools)Customization: modification of software to meet organization’s needs (trivial many; Use programming tools) Must weigh costs / benefitsMust weigh costs / benefits*

Selected Examples Of Application Programs Accounts receivable; Bond & stock management; Computer-aided design (CAD) ; document imaging; E- mail; EnterpriseResource planning (ERP); Groupware; Health care; HotelManagement; 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; Banner 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; Banner*

% LINES OF CODE CONVERTED TOTAL IMPLEMENTATION COSTS Effects Of Customizing Software On Total Implementation Costs

End-user Development End-users develop information system themselves, with little help from technical specialists; Using 4th generation tools (Part III of this course) *

End-user Development Strengths: Improved requirements determinationImproved requirements determination Increased user involvement & satisfactionIncreased user involvement & satisfaction Reduced application backlogReduced application backlog*

End-user Development Weaknesses: Relatively inefficientRelatively inefficient Slow transaction processingSlow transaction processing May carry high/hidden costMay carry high/hidden cost Nonprocedural approach makes it difficult for others to understand or updateNonprocedural approach makes it difficult for others to understand or update Managers are not really programmers; Take them away from their REAL work. *

Outsourcing Contracting: Computer center operationsComputer center operations Telecommunications networksTelecommunications networks Application developmentApplication development To external vendors (allow others to hold you by your throat?) *

System Building Methodologies Structured methodologies (ER approach to SDLC)Structured methodologies (ER approach to SDLC) Object-oriented software development (BMIS 342)Object-oriented software development (BMIS 342) Computer aided software engineering (CASE, BMIS 342)Computer aided software engineering (CASE, BMIS 342) System analysis and design (BMIS 444)System analysis and design (BMIS 444)*

Structured Methodologies Top down, step by step, each step builds on previous Structured analysisStructured analysis Structured designStructured design Structured programmingStructured programming FlowchartsFlowcharts*

Structured Analysis Defines system inputs, processes, outputsDefines system inputs, processes, outputs Partitions system into subsystems or modulesPartitions system into subsystems or modules Logical, graphical model of information flowLogical, graphical model of information flow Data flow diagram: graphical display of component processes, flow of dataData flow diagram: graphical display of component processes, flow of data*

SYMBOLS FOR DATA FLOW DIAGRAMS (DFD): DATA FLOW PROCESS SOURCE OR SINK FILE

DATA FLOW DIAGRAM: GENERATE BILL CUSTOMER GENERATE BALANCE GENERATE REPORT MANAGER PAYMENT FILE CUSTOMER FILE

Structured Analysis Data dictionary: controlled definitions of descriptions of all data, such as variable names & types of dataData dictionary: controlled definitions of descriptions of all data, such as variable names & types of data Process specifications: describes logic of processes at module levelProcess specifications: describes logic of processes at module level*

Program Flowchart Symbols: 11.32

Program flowchart: PROCESS A PROCESS B SEQUENCE PROCESS CPROCESS D R TRUE SELECTION PROCESS E S TRUE ITERATION

PROGRAM FLOWCHART: 1 END REPORT MORE? 2 PRINT 1 2 START READ >$10,000 <$10,000 PROCESS A PROCESS B

Object - Oriented Software Development De-emphasizes procedures (“what needs to be done” rather than “how to do it”)De-emphasizes procedures (“what needs to be done” rather than “how to do it”) Shifts focus from models & data to objects, which combine data & proceduresShifts focus from models & data to objects, which combine data & procedures “Reusable” objects“Reusable” objects Reduces development time & cost *

Software Engineering The establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machinesThe establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines Engineering: solution based on theoretical knowledgeEngineering: solution based on theoretical knowledge

Software Reengineering Salvages & upgrades aging softwareSalvages & upgrades aging software Delays expensive replacementDelays expensive replacement Reverse engineering: converting existing programs, files, database for use in new applicationsReverse engineering: converting existing programs, files, database for use in new applications*

Software Reengineering Revise design & program specificationsRevise design & program specifications Forward engineering: use revised materials to generate new, structured code; Structured & maintainable systemForward engineering: use revised materials to generate new, structured code; Structured & maintainable system*