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SDLC

SDLC . Information Systems Development Terms. SDLC - the development method used by most organizations today for large, complex systems Systems Analysts - IS professionals who specialize in analyzing and designing information systems

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SDLC

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  1. SDLC

  2. Information Systems Development Terms • SDLC - the development method used by most organizations today for large, complex systems • Systems Analysts - IS professionals who specialize in analyzing and designing information systems • Programmers - IS professionals who modify existing computer programs or write new computer programs to satisfy user requirements • Technical Specialists - experts in a certain type of technology, such as databases or telecommunications, who help create information systems

  3. Go Back to a previous Stage or Stop The Traditional SDLCA waterfall approach (1) Systems Investigation An eight-stage systems development life cycle (SDLC) (2) Systems Analysis (3) Systems Design (4) Programming (5) Testing (6) Implementation (7) Operation (8) Maintenance

  4. Key aspects with SDLC • Active end-user involvement • Throughout development process • Top Management Support • Steering committee represents top management and all functional areas affected by project • How will you measure system success? • Should be established up-front

  5. Phases in SDLC • System Investigation • Feasibility study determines the probability of success of proposed system’s development project. Includes … • Technical feasibility (will we be able to build the system?) • Economic feasibility (how much will it cost to build the system and how much will it benefit us?) • Behavioral feasibility (if we build the system, will it be accepted and used?)

  6. Phases in SDLC (continued) • Systems Analysis • Examines the business problem(s) that the organization plans to solve with information systems • Determines what the new system must do by examining: • Strengths and weaknesses of the existing system • Functions that the new systems must have to solve the business problem(s) • User information requirements for the new system • Develops initial working relationship with current end users

  7. Phases in SDLC (continued) • Systems Design • Describes how the system will fulfill the user requirements • Develop both logical design and physical design • Output => technical design or system specification… • system outputs, inputs, and user interfaces • hardware, software, databases, telecommunications, personnel, and procedures • how these components are integrated

  8. Phases in SDLC (continued) • Systems Design (cont’d) • Factors to consider during make-or-buy decision • On-time/On-budget • Full functionality • User acceptance • Favorable costs-to-benefits ratio • Low maintenance • Scalability • Integration with other systems • Minimal negative cross-impacts • Reusability • Customization (is source code available?)

  9. Phases in SDLC (continued) • Programming • the translation of the design specifications into computer code • structured programming techniques improve the logical flow of the program by decomposing the computer code into modules • issue of open-source vs proprietary development tools

  10. Phases in SDLC (continued) • Testing (quality assurance) • Checks to see if the computer code will produce the expected and desired results under certain conditions • Use combinations of black-box and white-box testing

  11. Phases in SDLC (continued) • Implementation • The process of converting from the old system to the new system • Four major conversion strategies • Parallel conversion: the old and new systems operate simultaneously for a period of time • Direct conversion: the old system is cut off and the new systems is turned on at a certain point in time • Pilot conversion: introduces the new system in one part of the organization • Phased conversion: introduces components of the new system in stages

  12. Phases in SDLC (continued)

  13. SDLC Phases • Operation • the new system will operate for a period of time, until it no longer meets its objectives • Maintenance (simultaneous with Operation) • debugging the programs • updating the system to accommodate changes in business conditions • adding new functionality to the system

  14. Alternatives to the SDLC • Prototyping • Starts with only a general idea of user requirements, and develops models of the system ‘until it’s right’ • Advantages: • Speeds up the development approach • Gives the users the opportunity to clarify their information requirements • Useful in the development of decision support systems and executive information systems • Disadvantages: • Replaces the systematic analysis and design stages of the SDLC - quality may be sacrificed • Can result in an excess of iterations

  15. Alternatives to the SDLC -- continued

  16. Alternatives to the SDLC -- continued • Joint Application Design (JAD) • A group-based method for collecting user requirements and creating staged designs • Advantages: • Saves time • Greater support for, and acceptance of new systems • Produces higher quality systems • Easier implementation • Lower training costs • Disadvantages: • Very difficult to get all users to JAD meetings • All the problems that may be caused by any group process

  17. Alternatives to the SDLC -- continued • Integrated Computer-Assisted Software Engineering (ICASE) Tools • Automate many of the tasks in the SDLC • Advantages: • Produces systems with a longer effective operational life • Speeds up the development process and result in systems that are more flexible and adaptable to changing business conditions • Results in excellent documentation • Disadvantages: • More expensive to build and maintain initial system • Requires more extensive and accurate definition of user needs and requirements • Difficult to customize and may be difficult to use with existing systems

  18. Alternatives to the SDLC -- continued • Rapid Application Development (RAD) • A method that can combine JAD, prototyping, and integrated CASE tools, to rapidly produce a high-quality system • Advantages: • Active involvement of users in the development process • Speeds the development process • Reduces development costs • Can create applications that are easier to maintain and modify • Disadvantages: • May result in systems with limited functionality and adaptability for change

  19. Alternatives to the SDLC -- continued • End User Development • Users perform ad hoc programming to solve business problems • Factors that drive the trends toward increased end-user computing and end-user development • More powerful, inexpensive desktop hardware • Increasingly diverse software capabilities • Increasingly computer literate population • Backlog of IS projects • Apparent cost savings • End-users (usually) don’t produce adequate documentation or perform adequate testing • Security may be breached

  20. Alternatives to the SDLC -- continued • Application Service Providers (ASPs) • Software obtained via subscription • Software resides on ASP’s systems • Software is accessed via Web or VPN • Subscriber does not have to host software on existing computer systems • Updates and bug fixes are provided by the ASP • ASP can provide help-desk support

  21. Alternatives to the SDLC -- continued • Web Services • Dynamic pages replicate software functionality • Eases maintenance • Do not need to touch each machine when installing updates

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