Lec 5 - SDLC 2009

Lec 5 - SDLC 2009 - Introduction to Systems Development Dr....

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Unformatted text preview: Introduction to Systems Development Dr. Jacqueline Wong DSE Department The Chinese University of Hong Kong 1 How TPSs manage data 2 Database Approach 3 Building the Right System: Feasibility Costs Up-front/one-time ⌧Software ($ millions !) ⌧Hardware ⌧Communications ⌧Data conversion ⌧Studies and Design ⌧Training Benefits Cost Savings ⌧Software maintenance ⌧Fewer errors ⌧Less data maintenance ⌧Less user training Increased Value ⌧Better access to data ⌧Better decisions ⌧Better communication ⌧More timely reports ⌧Faster reaction to change ⌧New products & services On-going costs ⌧Personnel ⌧Software upgrades ⌧Supplies ⌧Support ⌧Software & Hardware maintenance Strategic Advantages ⌧Lock out competitors Easy to estimate Hard to value 4 Participants in Systems Development Stakeholders individuals who, either themselves or through the area of the organization they represent, ultimately benefit from the systems development project Users who will interact w/ the systems regularly Systems Analyst professional who specializes in analyzing and designing business systems Programmer specialist responsible for modifying or developing programs to satisfy user requirements 5 Problems w/ existing system Desire to exploit new opportunities Increasing Competition Desire to make effective use of information Organization growth Merger or acquisition Chang in market or external environment New laws or regulations Typical Reasons to Initiate a Systems Development Project 6 Five Common reasons for systems requests Improved Services Reduced Cost Systems Requests Better Performance Stronger Controls More Information 7 Information Systems Planning is a long-range view of information technology use in the organization should provide a broad framework for future ensures better use of information systems resources success 8 The Steps of IS Planning Strategic plan Develop overall objectives Identify IS projects Set priorities and select projects Previously unplanned Systems projects Analyze resource requirements Set schedules and deadlines Develop IS planning document 9 Establishing Objectives for Systems Development Performance Objectives The quality or usefulness of the output The quality or usefulness of the format of the output The speed at which output is generates Cost Objectives Development Cost Costs related to the uniqueness of the system application Fixed investments in hardware and related equipment Ongoing operating costs of the system * Balancing performance and cost objectives within the overall framework of organizational goals can be challenging. 10 Traditional Systems Development Life Cycle (SDLC) Systems investigation understand problem Systems analysis understand solution Systems design select and plan best solution Systems implementation place solution into effect Systems maintenance and review evaluate results of solution 11 Systems Investigation Initiating Systems Investigation • • • • • • • • Problems in or opportunities for the system Objectives of systems investigation Overview of the proposed system Expected costs and benefits of the proposed system undertakes feasibility analysis establishes system development goals select system development methodology Prepares system investigation report Participants in Systems Investigation Feasibility Analysis • technical, operational, schedule, economic, legal,... The Systems Investigation Report 12 Steps in a preliminary investigation Understand the problem or opportunity A popular technique for investigating causes and effects is called a fishbone diagram Define the project scope and constraints Present vs future; internal vs external; mandatory vs desirable Perform fact-finding Analyze organizational charts Conduct interviews Review documentation Observer operations Conduct a user survey Evaluate feasibility Estimate project development time and cost Present results and recommendations to management Preliminary Investigation report for XXX system 13 A typical Preliminary Investigation Report Introduction Systems Request Summary Findings Recommendations Time & Cost Estimates Expected Benefits Appendix 14 Systems Analysis General Considerations Participants in Systems Analysis Data Collection Data Analysis Requirement Analysis The Systems Analysis Report 15 The Systems Analyst plays an important role in the development team Managers External Companies Software programmers System stakeholders Systems Analyst Technical specialists Users Vendors or Suppliers 16 SA Participants in Systems Analysis ⌧assemble a team to study the existing system ⌧develops a list of specific objectives and activities ⌧a schedule for meeting the objectives and completing the specific activities Data Collection ⌧the purpose is to seek additional information about the problems or needs identified in the systems investigation report ⌧identifying sources of data (internal and external) ⌧performing data collection ⌧following-up and clarification 17 SA Data Analysis ⌧the data collected in its raw from is usually not adequate to determine the effectiveness and efficiency of the existing system or the requirements for the new system. Data and Activity Modeling ⌧an entity-relationship diagram (ER diagram) ⌧a data flow diagram (DFD) Requirement Analysis • is to determine user, stakeholder, and organizational needs. ⌧Asking Directly ⌧Critical Success Factors ⌧Screen and Report Layout 18 Systems Design The primary result of the systems design phase is a technical design that details system outputs, inputs, and user interfaces; specifies hardware, software, databases, telecommunications, personnel, and procedures; and shows how these components are related. Two key aspects of systems design are logical and physical design. Logical design: description of the functional requirements of a system ⌧ Output design, Input design, Process design, File and database design, Telecommunications design, Procedures design, Controls and security design, and Personnel and job design. Physical design: specification of the characteristics of the system components necessary to put the logical design into action ⌧ Hardware design, Software design, Database design, Telecommunications design, Emergency Alternate Procedures and Disaster Recovery Systems Controls 19 Personnel Design, Procedures and Controls design. Prototyping Iteration 1 Determine Requirements an iterative approach to the systems development process Analyze Alternatives Specify design Implement design User Review Iteration 2 Determine Requirements Analyze Alternatives Specify design Implement design User Review Iteration N (Final) Determine Requirements Analyze Alternatives Specify design Implement design Changeover 20 Systems Implementation Hardware acquisition Software acquisition User preparation Renting (Short-term), Leasing (Long-term), Purchasing In-house developed software or externally developed software Personnel: hiring and training Site preparation Data preparation Installation Testing is the process of readying managers, decision makers, employees, other users, and stakeholders for the new systems Preparation if the location of the new system Conversion of manual files into computer files, or convert the data from the old system into the new system. The process of physically placing the computer equipment on the site and making it operational Unit testing system testing volume testing integration testing acceptance testing Start-up User acceptance Direct Conversion, Phase-in approach, Pilot start-up, or Parallel start-up 21 Systems Maintenance Reasons for maintenance Types of maintenance The request for maintenance form Performing maintenance The Financial implications of maintenance The relationship between maintenance and design 22 ...
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