System engineering analysis and design
- 1. System Engineering Analysis and design • When the system approach to problem solving is applied to development of IS for business solution it called as IS development or application development • System thinking is ‘ seeing the forest and the trees’ . It involves seeing interrelationship among systems rather than linear cause-effect for an event. It is seeing process of change among systems rather than snapshots of change wherever occurring.
- 2. • E.g. Virtualization • It means understanding of S/W and application on different platforms •
- 3. Systems Approach to Problem Solving Design the Solution Define the Problem Develop Alternative Solutions Select the Solution Implement the Solution MonitorandEvaluateResults
- 4. • The systems approach views a business process as a system that has 5 components: input, process, output, feedback and control. The systems approach to problem solving uses the systems orientation to conceptualize the nature of the problem. Under the systems orientation, all elements of a problem interact with one another. Consequently, the systems approach considers each "step" to influence and provide feedback on every other step
- 5. Approaches • Life Cycle Approach • Object Oriented Approach
- 6. Define A system is group of interrelated components working together toward a common goal by accepting input and producing output in an organized transformation process
- 7. Type • Natural System: human body, Galaxies etc • Man made: Government • Physical • Abstract: e.g. business models • Open: interact with environment • Closed
- 8. Information system development • When system approach is applied for information system solutions then it is called as Information system development
- 9. Traditional Systems Development Life Cycle Systems Implementation Product: Operational System Systems Investigation Product: Feasibility Study Systems Analysis Product: Functional Requirements Systems Design Product: System Specifications Systems Maintenance Product: Improved System Understand the Business Problem or Opportunity Develop an Information System Solution Implement the Information System Solution
- 10. • The traditional information systems development cycle is based upon the stages in the systems approach to problem solving, where each step is interdependent on the previous step: • Systems Investigation. This stage may begin with a formal information systems planning process to help sort out choices from many opportunities. Typically, due to the expense associated with information systems development this stage includes a cost/benefit analysis as part of a feasibility study.
- 11. • The Investigation Phase begins the preliminary study of the proposed information system solution to meet the e-business needs. Its focus is to seek to answer the questions: What are our opportunities, what are our priorities, and can IS be used to address these needs? • Because the process of application development can be costly both in time and resources, the system investigation phase begins with a Feasibility Study. The goal of feasibility studies is to evaluate alternative systems and to propose the most feasible and desirable systems. Feasibility is assessed across four major categories:
- 12. • Organizational Feasibility. This focuses on how well a proposed information system supports the objectives of the organization. • Technical Feasibility. This ascertains whether reliable hardware and software capable of meeting the needs of the proposed system can be acquired or developed. • Operational Feasibility. This refers to the willingness and ability of the management, employees, customers, suppliers, and others to operate, use, and support a proposed system.
- 13. • Economic Feasibility. This is concerned with whether the proposed IS benefits are greater than its costs. This area is particularly concerned with financial affordability -- whether the firm can pay to develop the system. A cost/benefit analysis is used to weigh the total costs a new system is likely to incur against the total anticipated benefits to be gained. This includes determining tangible costs (such as hardware and software purchases and employee salaries) and intangible costs such as effects on employee morale and disruptions in productivity during the installation of the new system. Benefits too can be either tangible (such as reduced inventory and carrying costs) or intangible (higher customer satisfaction).
- 15. Systems Analysis • It is extension of system investigation. It is in- depth analysis of several basic activities. Ultimately it is an indepth study of end user information needs that produces functional requirements
- 16. Cont……………. • Organizational Analysis. An effective IS can only be designed with a full awareness of the organization it will serve. Systems analysis then begins with a thorough analysis of the organization, its management structure, its people, its business activities, the environmental systems it deals with, and its current information systems.
- 17. • Analysis of the Present System. If a system already exists, it is useful to study it to help assess how it can be improved or replaced by the proposed system. In particular, the analysis should identify how things are currently done (such as user interface methods) and determine how they should be done in the system being designed.
- 18. • Logical Analysis • It is blueprint of current system that display only what the current system does without regard for how it does it. • Suppose order are in inbox of executive. But logical analysis will take it as order stored in hard disk. Thus What part is important not How
- 19. • Functional Requirements Analysis. Functional requirements specify the information systems capabilities required to meet the information needs of users. In particular, functional requirements analysis must specify:
- 20. • User Interface Requirements. What user input will be needed? The input/output needs of end users must be supported by the IS. • Processing Requirements. Functional analysis must specify the processing requirements necessary to perform all the activities involved in converting input into output. The objective is to determine what must be done; not how it will be done. • Storage Requirements. What data must be stored and retrieved? Organization, content, and size of databases and procedures for maintenance must be specified. • Control Requirements. What control reports must be produced? What data input controls are needed? Issues of accuracy, validity, safety, security, and adaptability must be specified.
- 21. Methods for assessing requirements • Interviewing • Brainstorming • Questionnaires • Quality function deployment: is a quality management technique that translates the needs of customers into technical requirements
- 22. Joint application development • It is an information gathering technique that allows the project team, users and management to work together to identify requirements. 10 to 20 participants
- 23. System design • From output of System analysis i.e. requirement specification second phase i.e. system design starts. • Is the process of defining the architecture , components , modules interfaces and data of a system to satisfy specified requirements. • In logical view what is to be accomplished will be designed (DFD, ER Etc) • In physical view how it will be accomplished will be design (Hardware, software,etc)
- 24. System Design Phase of detailing how a system will meet the information requirements determined by the systems analysis. This phase is broken into two sub phases: 1. Logical design 1st phase, lays out the components of the information system and their relationship to each other as they would appear to users. 2. Physical design 2nd phase, the process of translating the abstract logical model into the specific technical design for the new system Tools and Techniques used for designing: Flow Chart Dataflow Diagrams (DFDs) Data Dictionary Structured English Decision Table Decision Tree Design specifications include: Output, Input, User interface, Database design, Manual procedures , Documentation etc..
- 25. System design USER Interface Design Data Design Process Design Screen Form and dialog design Data element and structure design Program and procedure design
- 26. objectives • Practicality • Flexibility • Efficiency • Security
- 27. Two level of design • Conceptual design helps in generating alternative MIS designs and help in selecting one. • This selected one is further given shape of detailed MIS design
- 28. Conceptual design • Define Problem • Set system objectives • Identify constraints (by customers, government , suppliers, management, money etc) • Determine information needs and sources • Develop various designs (alternatives) • Documentation of selected design (overall flow, input, output) • Report preparation
- 29. Detailed system design • Project planning and control :should be considered as a project for efficiency • Involve the user • Detailed sub system definition • System-- subsystem->function-> task-> operational element • Output/Input design • Forms, formats etc of output and input
- 30. • Feedback once again from user • Database design • Procedure design for data entry, run time procedures( e.g. to load printer with specific paper), error handling procedure, security and backup procedures, software documenting procedures • Design documentation
- 31. Implementation • First step is to plan • Acquiring facilities and space • Developing organization mindset for MIS and its procedures • Acquiring hardware and software • Coding • Testing • Creation of forms and database • Documentation • User training
- 32. Installation • Conversion of old into new • Parallel: run old and new simultaneously • Pilot(modular): Install in one part at a time • Phased: implement in one of function • Cutover (direct) : start directly with new system
- 33. Evaluation and Maintenance • On basis of timeliness, relevance, accuracy, completeness, adequacy, exception-bases • Cost-benefit evaluation • Maintenance: the process of monitoring, evaluating, and modifying of existing information systems to make required or desirable improvement may be termed as system maintenance.
- 34. • Corrective Maintenance • Adaptive • Perfective: adding new programs or modifying existing programs