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Chaper 1 sdlc


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Chaper 1 sdlc

  1. 1. SUG 653 GIS II Chapter 1: System Development Life Cycle (SDLC) 1. System Development Team: - GIS Manager - GIS Analyst a. Technology assessment b. Software development c. Data development
  2. 2. How to Be An Efficient GIS Manager • A good GIS manager ensures that: a. A good system is selected. b. The system works efficiently. c. It contributes to the organisations strategic objectives. d. It is sustainable. • Aware the consequences of failure are severe for you and other GIS users. • Success demands sharing experience and knowledge with others.
  3. 3. System Defined • A system is a set of: – Interrelated components. – Working together. – For a common purpose.
  4. 4. • A Generic System Model (with Six Components) 1.Boundary 2.Inputs 3.Outputs 4.Processing 5.Controls 6.Feedback
  5. 5. 1. Information System defined • An Information System is: • a type of fabricated system • used by one or more persons • to help them accomplish some task or assignment they • Have 2. An Information System: • supports policies & procedures • has three components - data, people, procedures - in • addition to the six general system components- (i.e. • input, output, processing, control, feedback and • boundary)
  6. 6. • Information Systems • Information systems are the support structure for meeting the company’s strategies and goals • Information systems help knowledge workers perform their jobs
  7. 7. • Automated Information System • An Automated Information System is: a. a type of fabricated system b. used by one or more persons c. to help them accomplish some task or assignment they have d. Utilizes hardware and software • An Automated Information System has three basic characteristics to consider: a. DATA - input, output, or already stored electronically b. FUNCTIONS - transformations or actions taken c. BEHAVIOR - the observable effects from interaction
  8. 8. GIS • A GIS is a computer application that stores, retrieves, manipulates, analyzes, and displays geographically referenced information or geospatial data. • Components of GIS 1. People – the user of the system 2. Applications – the process and programs they use to do their work 3. Data – the information needed to support those applications 4. Software – the core GIS software 5. Hardware – the physical components on which the system runs
  9. 9. Systems Development Life Cycle (SDLC) • All systems have a life cycle or a series of stages they naturally undergo. • Information systems are developed using the systems development life cycle. • It is so called systems development life cycle (SDLC) because the development processes are derived from the system’s life cycle.
  10. 10. • Systems development life cycle (SDLC) is a structured step-by-step approach for developing information systems. It is a methodology that partitions the system development process into formal stages/phases that must be completed sequentially with a very formal division of labor between end users and information system specialists.
  11. 11. SDLC – What can we say about it • It provides a framework to organize a large number of activities that the development process incorporates • It is usually divided into phases and each phase consists of activities • The phases are usually presented as a sequential set with each phase ending with a set of deliverables • There are a number of life-cycle approaches available: Predictive approach (e.g. Waterfall model) , Adaptive approach (e.g. Spiral model) • Each approach has its own terminology even though they all strive to present the same information
  12. 12. Phases in SDLC • The number and name of the phase in a SDLC varies. • The phase can range between 4 to 8 or more stages, but the primary phases are 1. Planning (just after Conception) 2. Analysis 3. Design 4. Implementation 5. Maintenance (starting Maturity) • Each culminating in a deliverable, either a written document or a piece of software (or both)
  13. 13. Model of a SDLC
  14. 14. Activities in Each Phase • Project planning – initiate, ensure feasibility, plan schedule, obtain approval for project • Analysis – understand business needs and processing requirements • Design – define solution system based on requirements and analysis decisions • Implementation – construct, test, train users, and install new system • Maintenance – keep system running and improve
  15. 15. Models 1.Models • Representation of an important aspect of real world, but not same as real thing • Models come in many forms - Physical analogs, mathematical, graphical • Abstraction used to separate out aspect. System development models are highly abstract - Depict inputs, outputs, processes, data, objects, interact ions, locations, networks, and devices • PERT or Gantt charts: model project itself
  16. 16. Approaches to SDLC • Two main approaches to SDLC 1. Predictive approach – assumes project can be planned out in advance 2. Adaptive approach – more flexible, assumes project cannot be planned out in advance • All projects use some variations of SDLC
  17. 17. The Traditional Predictive SDLC Approaches 1. Pure waterfall approach (predictive SDLC) • Assumes project phases can be sequentially executed • System development progresses in a straight line fashion • Project drops over the “waterfall” into the next phase 2. Modified waterfall approach • Tempers pure waterfall by recognizing phase overlap • Informs many current projects and company systems
  18. 18. What makes Systems DEVELOPMENT a difficult activity? • Initially, problem domains (areas) tend to have poorly defined boundaries • Problem domain solutions are artificial • Problem domains are dynamic • Problem domain solutions usually require interdisciplinary knowledge and skills • Systems Analyst’s knowledgebase is continually expanding • Systems Analysis and Design is a highly cognitive activity • Working with people