Analysis And Design Tools In Software Engineering Ppt

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Systems Analysis and Design

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Systems Analysis and Design

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Systems Analysis and Design
Objectives • Define the terms system, analysis, and design • Describe the principal functions of the systems analyst • List and describe the phases of the systems development life cycle • Describe the various data gathering and analysis tools • Describe a selection of systems design tools • Explain the concept of prototyping • Explain the role of the maintenance task in the systems development life cycle
Contents • What is Systems Analysis and Design? • Systems Analyst • Systems Development Life Cycle • Preliminary Investigation • Analysis • Design • Development • Implementation
Systems Analysis and Design What is it? • System • organized set of related components established to accomplish certain task • Natural • Planned and placed by people • Computer system • A system that has computers as one of its components
Systems Analysis and Design What is it? • Systems analysis Process of studying an existing system to determine how it works and how it meets user needs • Systems design Process of developing a plan for an improved system, based upon the results of the systems analysis
Systems Analysis and Design Why do it? • Impetus for change • Internal force • External force • Authority for change • Approval of higher management
Systems Analyst • Professional computer employee who performs analysis and design • Change agent • Overcome reluctance of users to change • Typical career path • Programmer • Programmer / Analyst • Systems Analyst
Systems AnalystFunctions Coordination • Schedules and system-related tasks • Personnel • Manager • Programmers • Users • Vendors of computer equipment • Contractors
Systems AnalystFunctions Communication • Oral presentations • Written documentation Planning and design • Plans and designs new system • Involved from beginning of project through final implementation of the system
Systems AnalystPersonal Qualities • Analytical mind • Good communication skills • Self-discipline • Self-direction • Organizational skills • Creativity • Ability to work without tangible results
SDLCSystems Development Life Cycle • Preliminary investigation • Analysis • Design • Development • Implementation
SDLCPreliminary Investigation • Feasibility study / System survey • Determine the problem • Describe the problem • Understand management decisions • Organizational chart • Informal hierarchy • Produces rough plan and what to do
SDLCPreliminary Investigation Problem Definition • Nature of the problem Separate problem from symptoms of problem • Scope of the project Budget and schedule • Objectives of the project What user thinks system should do
SDLCPreliminary Investigation Report What you have found Recommendations Financially feasible
SDLCPreliminary Investigation Resulting Management Decision • Drop • Fix a simple problem • Authorize the analysis phase
SDLCAnalysis • Understand the existing system • Gather data • Analyze data • Establish system requirements
SDLCAnalysis – Data Gathering • Written documents • Interviews • Structured • Unstructured • Questionnaires • Observation • Visits by appointment • Participant observation • Sampling
SDLCAnalysis – Analyze Data • How the current system works • Determine system requirements • Basis for documentation • Tools • Data flow diagram (DFD) • Decision tables
SDLCAnalysis – Data Flow Diagram
SDLCAnalysis –Decision Tables
SDLCAnalysis – System Requirements • Detailed list of things the system must be able to do • Design is based upon system requirements • Agreement upon requirements is needed before proceeding
SDLCAnalysis – Report to Management • Summarize problems • Describe requirements • Cost analysis • Recommendations for next step • Obtain authorization to proceed
SDLCDesign • Planning the new system • Two phases • Preliminary design • Detail design
SDLCPreliminary Design Major system aspects • Centralized or distributed • Online or batch • PC-based? • How will input be captured? • Necessary reports
SDLCPreliminary Design • Make or buy decision • Packaged software • Meet at least 75% of requirements? • Change business procedures for part or all of remainder? • Customize for part of all of remainder? • Custom software • Programmers write code • Outsourcing • System is developed by external organization
SDLCPreliminary Design • Create an overall plan • Offer alternatives that meet requirements • Explain differences • Evaluate costs
SDLCPreliminary Design • Build a prototype • Limited working system of subset • Does not need true functionality • Output looks like anticipated system output • Working model that can be modified and fine-tuned • Uses high-level software tools – CASE • Best for small-scale systems
SDLCPreliminary Design CASE tools Computer-Aided Software Engineering • Supports specific analysis and design tasks • Integrated environment that supports the entire systems development process
SDLCPreliminary Design Presentation • All alternatives • Selected plan • Prototype of the system • Obtain authorization to proceed
SDLCDetail Design Parts of detail design phase • Output requirements • Input requirements • Files and databases • Systems processing • Systems controls and backup
SDLCDetail Design Output requirements • Medium • Type of reports • Contents
SDLCDetail Design
SDLCDetail Design Input requirements • Medium • Content • Input forms • Validation • Volume
SDLCDetail Design Files and Databases • Organization • Access • Format of records • Coordinate with database administrator regarding external databases and updating
SDLCDetail Design Flowchart Symbols
SDLCDetail Design
SDLCDetail Design Systems Controls and Backup • Insure that input is processed correctly • Prevent fraud and tampering • System journals • Backup of system files
SDLCDetail Design Report to Management • Detailed design specifications report • Presentation • Obtain authorization to proceed
SDLCDevelopment • Doing the work to bring the new system into being • Scheduling
SDLCDevelopment • Programming • Refine the design • Detailed logic flowcharts and pseudocode • Testing • Unit testing • System testing • Volume testing
SDLCImplementation • Converting to the new system • Training • Equipment conversion • File conversion • System conversion • Auditing • Evaluation • Maintenance
SDLCImplementation – Training • Begin during testing • User's manual (Technical Writers) • Hands-on • Training consideration • Space • Equipment • Data • User's schedules
SDLCImplementation – Conversion • Equipment • Planning • Installation of new equipment • File • Manual to electronic • Special programs to convert old format to new
SDLCImplementation – Conversion • System • Direct conversion • Phased conversion • Pilot conversion • Parallel conversion
SDLCImplementation –Auditing • Audit trail • Trace output back to source
SDLCImplementation – Evaluation • Working • Meets original requirements • Benefits • Meets budget • Improvements
SDLCImplementation – Maintenance Ongoing activity for life of system
Thank you