functionality in the system. If the project schedule starts to slip, it can be readjusted by removing functionality from the version or prototype under development. The waterfall model is the worst choice, because it does not allow for easy schedule changes. Schedule visibility One of the greatest challenges in systems development is knowing whether a project is on schedule. This is particularly true of the structured methods because design and implementation occur at the end of the project. The RAD models move many of the critical design decisions to an earlier point in the project to help project managers to recognize and address risk factors and keep expectations in check.
40 Methodologies Methodologies Methodologies Methodologies Comprehensive guidelines to follow for completing every SDLC activity Collection of models, tools, and techniques
41 Relationships Among Components Relationships Among Components of a Methodology of a Methodology
42 Models Models Models Representation of an important aspect of real world, but not same as real thing Abstraction used to separate out aspect • physical (like a model of an airplane) • abstract (e.g. in form of mathematical notation or in graphical form) Models in SDLC are graphical: diagrams and charts Project planning and budgeting aids
43 Some Models Used in SDLC Some Models Used in SDLC
44 Tools Tools Tools Software support that helps create models or other required project components Range from simple drawing programs to complex CASE tools to project management software
45 Some Tools Used in SDLC Some Tools Used in SDLC
46 Techniques Techniques Techniques Collection of guidelines that help analysts complete a system development activity or task Can be step-by-step instructions or just general advice
47 Some Techniques Used in SDLC Some Techniques Used in SDLC
48 Two Approaches to System Two Approaches to System Development Development Traditional approach Traditional approach Also called structured system development Structured analysis and design technique (SADT) Includes information engineering (IE) Object-oriented approach Object-oriented approach Also called OOA, OOD, and OOP Views information system as collection of interacting objects that work together to accomplish tasks
49 Structured Analysis Structured Analysis Define what system needs to do (processing requirements) Define data system needs to store and use (data requirements) Define inputs and outputs Define how functions work together to accomplish tasks Data flow diagrams (DFD) and entity relationship diagrams (ERD) show results of structured analysis
50 Data Flow Diagram (DFD) Created Data Flow Diagram (DFD) Created Using Structured Analysis Using Structured Analysis Technique Technique
51 Entity-Relationship Diagram (ERD) Entity-Relationship Diagram (ERD) Created Using Structured Analysis Created Using Structured Analysis Technique Technique
52 Structured Analysis Leads to Structured Analysis Leads to Structured Design and Structured Structured Design and Structured Programming Programming
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- Fall '19