Unit 2 System Life Cycle Topics Covered System Life Cycle New Approaches to design Resources for new systems Processing Alternatives Goals of System Design System Life Cycle Inception: Respond to idea for system Sketch outline of system,outpt,input and files. Feasibility Study: Describe existing methods of processing information,output,input,file processing. Study of software and hardware alternatives. Determine feasibilty of alternatives. Choose most optimal solution. System Analysis: Complete analysis of existing system and document it. Collect data on file specifications and transactions. Requirement Analysis: Repeated meeting with users to determine their needs and to review of design. Design: Develop design from user requirements. Choose new design approaches. Specifications: Develop specifications as far as needed for chosen design strategy. Programming: Develop program specifications ,modules, schedule and work plan Testing: Conduct unit, Integrated and acceptance tests. Training: Plan and conduct training programs organized by user section. Conversion: Plan detailed conversion requirements and analyze the impact of conversion on the whole organization. Operations: Routine maintenance and enhancements New Approaches for Design Traditional Design Approaches to custom System Application Generators allow user to see quickly what the system actually does. Advantage: Reduce programming Time Application Generator • The eGen Application Generator, also known as the eGen utility generates Java applications from a COBOL and a user- defined script file. Application Packages Application Packages The package can consist of program code and hardware that accomplish some part of desired applications for eg:An org buys a package to maintain various employee benefits system and produce various reports. Advantage : Shorten Development Time Application packages Application packages perform business- specific functions, as opposed to operating system. Most important is the fact that while operating system software upgrades are typically transparent to the business community, application package upgrades are not. • Human resource management (HRM) software manages internal payroll, benefits, insurance, and other functions related to administration of inhouse staff. • Customer relationship management (CRM) software addresses customer management functionality and is primarily used by customer- facing departments. CRM software has grown in popularity . Prototyping The prototype is model of the final system. It allows the user to see some concrete features of the system. 2 Types of prototype 1)Throw Away 2)Incremental(continuosly modified to evolve into the final application) Provides immediate Feedback End-User Programming : A number of organizations are encouraging end users to write their own programs. Special languages and tools make this more appealing than it would be using procedural languages. Reduces demand for applications Final System End-User Programming The Programming by example (PbE) approach reduces the need for the user to learn the abstractions of a classic programming language. The user instead introduces some examples of the desired results and/or operations that should be performed on the data, and the PbE system infers the correct abstractions corresponding to a program that produces this output. Demands and Resources of IS Dept Demand Resource Operating existing System Equipment & Human Maintenance Enhancements Human Equipment, Operator, Programmer etc Developing new information HR(Clerks,Data Entry System operator,System Analyst, Network Administrator, System Programmer(needed in large installation they work with the control S/W of the system,Managers(Co- ordinators of Sytem Operations and System design) Processing Alternatives Within broad cost constraints SA should design very flexible and user –oriented information Systems. On-Line Processing: For all the systems that are online there are several alternatives for the underlying computer system. The availability of low-cost H/W and the explosion in the availability of very powerful processors and mini and microcomputers have provided a major impetus for online systems. Communication costs have been dropping as this industry becomes more competitive and technological advances occur. Originally online systems were justified because of the need to coordinate actions at different geographic locations and to have fast response. But today costs have been reduced to the point that online systems are the standard for new designs. An analyst in today’s environment should seriously consider online features for almost every system being developed. Criteria For Deciding Processing Alternatives • Physical location of the database. • Location for updating and accessing the database. • Costs for equipment and communications • User Reactions. • Management Considerations. Control of Management over applications Control of Management over processing Communication between subsystems Coordination level between subsystems Input alternatives Input: Recently the trend in the information systems has been toward collecting data as close to its source as possible. The objective this philosophy is to eliminate the data transcription wherever feasible. This will avoid errors and reduce the time required to enter the data into the computer. Online interaction should be clear and polite. The designer should try to avoid a cumbersome input command structure and emphasize natural response. For online data entry, the system should provide courteous error messages. Messages should explain the error politely. It might be advisable to give no explanation unless the user types a question mark. That way those familiar with the system can avoid tedious error message that were really designed for people with less experience. Output Alternatives A wide variety of output alternatives are available. The most conventional form for output is impact line printer. The major advantage of line printer is that it can make multiple copies of the same report using carbon paper. There are number of nonimpact printers that operate at much higher speeds. The primary technology is laser printer. Microfilm is an output medium that has been used increasingly for data that have to be kept for historical purposes. The major disadvantage with microfilm is that a special device needed to read it and special attachments must be used to photocopy one frame of the film. Output occurs at much higher speed than printing. Output rates in hundred-thousand characters per second range. One of the other output storage media is image. Goals of System Design 1. Understand the existing system Problem and the existing solution. 2. Suggest improvement to present procedures. 3. Assess the feasibility of using new system. 4. Design the possible system within the limits of cost and technology. 5. Plan Programming and testing of the system. 6. Plan the complete implementation of the system.
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