System development
- 1. SYSTEM DEVELOPMENT • It includes those activities that go into producing an IS solution to organizational problems • It consists of two phases: System Analysis- includes analysis of a problem which is to be solved. It is a phase of system development process in which the system analyst determines that a new system should accomplish System Design –provides details of how a system will meet the information requirements as determined by the system analyst/system development team.
- 2. SYSTEM DEVELOPMENT APPROACHES 1.WATERFALL MODEL/SDLC MODEL Project definition: Recognition of need • Whether or not the organization has a problem and whether or not it can be solved by launching a new system • Preliminary survey is needed to see whether the alternative system can solve the problem • All bottlenecks, inefficient existing procedures and the parts which needs computerization • If problem is serious analyst is called, who prepares a statement specifying the scope and causes of a problem
- 3. 2.SYSTEM ANALYSIS: • Analysis of problem of existing system is undertaken and how the new system can overcome it. • It is detailed study of various operations performed b a system and their relationship within and outside the system. • Data is collected regarding the above files, decision points ,transactions handled by an existing system • Various tools used are interviews, questionnaires, in site observation etc • Once analysis is done analyst has a firm understanding of what can be done to overcome various problems
- 4. 3.SYSTEM DESIGN • Most creative and challenging phase • It describes how the chosen system will be developed • It prescribes the technical specifications, that are to be applied • It also includes construction of programs and their testing Steps involved are: • To determine how input is to be produced • It involves designing of input data and database that meets the output requirements • Data processing phase is handled through program construction & testing, including the list of programs needed to meet systems objectives
- 5. 4.IMPLEMENTATION • Is less creative • Related to user training, site preparation and file conversion 5.POST IMPLEMENTATION • After the system is installed • It consists of system evaluation and • EVALUATION: analysis of how the new system is achieving its objectives • MAINTAINENCE: involves maintaining the hardware ,software and other devices • Also includes enhancing the capacity of the present system either by updating hardware, software or another balancing devices
- 7. ADVANTAGES OF SDLC • Requirements can be expressed in structured form so SDLC provides chronological stages • Project scheduling and its execution can be determined well in advance • Once a system is developed and is in place, enhancement in its capacity can be achieved on continuous basis, in a limited extent without disturbing the system
- 8. LIMITATIONS • Is ill-suited for developing decision oriented systems • Quite rigid and inflexible • Is very resource intensive • Real projects rarely follow the sequential flow that the model proposes. • Developing a system using the Waterfall Model can be a long, painstaking process that does not yield a working version of the system until late in the process
- 9. PROTOTYPE MODEL • The Prototyping Model was developed on the assumption that it is often difficult to know all of your requirements at the beginning of a project • In this approach, a prototype of the system is developed. • Prototype is a comprehensive system and does not include all the requirements of the user • Once it becomes operational, it is further refined until it confirms users requirements • Used where identification of requirements is difficult and may change during the development process
- 10. STEPS: • Identification of basic requirements • Developing the initial prototype • Using the initial prototype • Redefining and enhancing the prototype
- 11. Identification of basic information requirements Developing the initial prototype Using the initial prototype Operational prototype If not accepted Working prototype Revising and enhancing working prototype If accepted If accepted
- 12. ADVANTAGES • In a situation where there is uncertainty about information requirements or design solution • Morale and satisfaction of users remain high • System can be developed easily
- 13. LIMITATIONS • Large systems must be divided so that prototype can be developed • May encourage the developers to move to quickly • Final steps of polishing may not be carried out • Developers assume testing could be handled by end-users.
- 14. Incremental Model • The problems with the Waterfall Model created a demand for a new method of developing systems which could provide faster results, require less up-front information, and offer greater flexibility. • With Iterative Development, the project is divided into small parts. This allows the development team to demonstrate results earlier on in the process and obtain valuable feedback from system users • The incremental model is an intuitive approach to the waterfall model. Multiple development cycles take place here, making the life cycle a “multi-waterfall” cycle. Cycles are divided up into smaller, more easily managed iterations
- 15. • A working version of software is produced during the first iteration, so you have working software early on during the software life cycle. • the software products which are produced at the end of each step (or series of steps) can go into production immediately as incremental releases. • It is a popular model software evolution used by many commercial software companies and system vendor. Incremental software development model may be applicable to projects where: - Software Requirements are well defined - The basic software functionality are required early
- 17. Advantages • Generates working software quickly and early during the software life cycle. • More flexible – less costly to change scope and requirements. • Easier to test and debug during a smaller iteration. • Easier to manage risk because risky pieces are identified and handled during its iteration. • Each iteration is an easily managed milestone. Disadvantages • Each phase of an iteration is rigid and do not overlap each other. • Problems may arise pertaining to system architecture because not all requirements are gathered up front for the entire software life cycle.
- 18. Spiral Model • The Spiral Model was designed to include the best features from the Waterfall and Prototyping models, and introduces a new component - risk-assessment • The term “spiral” is used to describe the process that is followed as the development of the system takes place • Similar to the Prototyping Model, an initial version of the system is developed, and then repetitively modified based on input received from customer evaluations. • Unlike the Prototyping Model, however, the development of each version of the system is carefully designed using the steps involved in the Waterfall Model. • With each iteration around the spiral (beginning at the center and working outward), progressively more complete versions of the system are built.
- 19. • The spiral model has four phases: Planning, Risk Analysis, Engineering and Evaluation. • Requirements are gathered during the planning phase. • In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. A prototype is produced at the end of the risk analysis phase. • Software is produced in the engineering phase, along with testing at the end of the phase. • The evaluation phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral.
- 21. Advantages • High amount of risk analysis • Good for large and mission-critical projects. • Software is produced early in the software life cycle. Disadvantages • Can be a costly model to use. • Risk analysis requires highly specific expertise. • Project’s success is highly dependent on the risk analysis phase. • Doesn’t work well for smaller projects.
- 22. SYSTEM ANALYSIS The basic objective of System analysis is to determine feasibility of a system and how it will meet the requirements of the users. This job is assigned to system analyst System analysis involves the following aspects of system development: • Feasibility study • Requirement analysis • Structured analysis
- 23. FEASIBILITY STUDY •A process of determining whether a system is appropriate in the context of organizational resources and constraints and meets the user requirements. •Basic objective is to identify whether the proposed system is feasible and will be more appropriate than the existing system. •System analyst defines the problems or opportunities ,establishes overall objectives of the system and defines the scope of the system. •It covers economic feasibility, technical feasibility ,operational feasibility and legal feasibility .
- 24. • Economic feasibility: involves determination of whether the given system is economically viable (cost-benefit analysis) • Technical feasibility: analyses whether the system is technically viable with the available hardware, software and technical resources • Operational / behavioral feasibility: whether the proposed system will work efficiently with the existing managerial and organizational framework (resistance from people, management) • Legal feasibility: tries to ensure whether the new system meets the requirements of various IT regulations such as privacy laws., cyber crime laws, international laws etc.
- 25. STEPS IN FESIBILITY STUDY • Constitution of a project team • Identification of a potential candidate systems • Identification of characteristics of candidate systems • Performance and cost evaluation • Weighing system performance and cost data • Selection of the best system • Preparation of feasibility report
- 26. REQUIREMENT ANALYSIS Most crucial stage of system analysis in which analysis is done about who requires what information in what form and when. It defines the scope of the system and the functions it is expected to perform. Tools used are • Procedures and forms used • On-site observation • Interviews • Questionnaires • System used in other organizations
- 27. STRUCTURED ANALYSIS • It is graphic that presents a picture of what is being specified and is a conceptually easy to understand • The process used in structured analysis is partitioned so that a clear picture of progression from general to specific in the system flow emerges • It is logical rather than physical • Certain tasks that are normally carried out late in the system development are undertaken at the analysis phase.
- 28. SYSTEM DESIGN • This is the most crucial stage of system development process as the design determines the success or failure of the system. • System design involves: 1. Reviewing the system’s informational and functional requirements and 2. Developing a model of the new system , including logical and physical specifications of outputs, inputs, processing , storage and procedures. • Logical design: also known as conceptual design , lays out the components of the system and their relationship to each other as they appear to users.
- 29. • It shows what the system will do as opposed to how it is actually implemented physically. • It contains input/output specifications ,file specifications and processing specifications. • Physical design: also known as detailed design., translates the abstract logical design into specific technical for the new system. it contains details of output design, input design, data storage design, processing design, and procedure design.
- 30. Documentation • After completion of system analysis and design , documentation is required. • It describes how an IS works from both, a technical and end-user standpoint. • It is a written record of different phases of a system development and establishes design and performance criteria for these phases. • Documentation should be done for all types of personnel who come in contact with the system. These personnel are : 1. End users 2. Secondary users 3. Computer operating personnel 4. Trainers
- 31. Methods of documentation 1. Conventional (cookbook) 2. Play script 3. Caption 4. Matrix 5. Flowchart
- 32. Tools for system analysis and design • In a system development process, one of the basic objectives is to complete the development process in as short time as possible • For this purpose various methodologies are used. 1. Data flow diagrams 2. Flowchart 3. Structured design 4. Structured programming 5. Object oriented development 6. Computer-aided software engineering
- 33. SYSTEM TESTING • If a system is installed without testing , two types of problems can occur: • If the system has an error ,it may appear later. The time lag between the cause and appearance of the problem may enhance correction time • The system errors may effect files and record s in the system and a small system error may explode into a much larger problem. • Testing tries to ensure that the system produces desired results under known conditions • Its utility as a user oriented vehicle before implementation
- 34. STEPS IN TESTING • F or system testing ,a testing plan showing sequence of testing, time schedule and personnel involved in testing should be prepared. After finalizing this plan , the following steps should be followed: • PROGRAM TESTING : syntax and logical errors • STRING TESTING : Each program must be tested independently as well as jointly to ensure that all programs work well jointly • SYSTEM TESTING: it tests the functioning of the system as a whole. It includes forced system failure and validation of the entire system. • ACCEPTANCE TESING: provides final certification that the system is ready to be used.
- 35. SYSTEM IMPLEMENTATION After the analysis ,design and testing of a system ,it is ready for implementation and maintenance. There are basically 3 types: • Implementation of a computer system to replace a manual system which requires acquisition of a computer hardware and software, file conversion, creating accurate files, and user training. • Implementation of a new computer system to replace an existing system like from mainframe to a network of mini computers. • Implementation of a modified application to replace an existing one using the same computer
- 36. HARDWARE AQUISITION The type of hardware that is required for implementing a system is specified in system analysis and design documentation. After the specifications are made the type of computer may be chosen for acquisition (main frame, mini computer and micro computer). HARDWARE EVALUATION For acquiring a computer hardware two aspects are evaluated: • Hardware capability • Vendor capability Hardware capability :Information is generally collected from different sources like vendors catalogues, other publications and current users of the same hardware A committee is formed which evaluates H/W with the help of certain pre-determined criteria. For using these criteria in evaluation three approaches can be adopted:
- 37. APPROACHES • Ad hoc approach: least methodological, uses personal opinions, including biases , not a scientific approach • Scoring approach: characteristics of each hardware is listed and each one is given a score in relation to max rating points. The alternative having max points is selected • Cost-value approach: monetary value is assigned to different characteristics of hardware alternatives. The alternative which gives the highest value in comparison to its price is selected. Vendor capability :various criteria like delivery time, performance records, user training and number of hardware installed should be taken into consideration. Again the same approaches are used.
- 38. HARDWARE ACQUISITION METHODS 1. Rental directly from the manufacturer: Is a form of lease by the manufacturer. May be paid monthly or any other period decided by the manufacturer and the user. Reasons for preferring rental option are: • No investment required in procuring the hardware • It makes it easy to change to other hardware systems (no risk of technological obsolescence) • Insurance, maintenance and other expenses are included in rental charges • Rental charge is tax deductible 2. Leasing through a third party: the lessor (a leasing company) remains the owner of the hardware and charges rent from the user. Advantages are: No fund is required for acquiring hardware system and the technological risk is borne to the lessor • Lease charges are generally lower as compared to rental charges for the same period
- 39. CONTD.. Limitation are :in the absence of up gradation clause the user may not be able to exchange the leased system for another system If the lease term is terminated, it may involve heavy financial penalty 3. Outright purchase: assuming all the risks of ownership including taxes insurance and technical obsolescence Its advantages are: There is a flexibility of modification of the hardware system at will. Tax benefits are available in the form of depreciation
- 40. SOFTWARE AQUISITION • SELECTION OF A SYSTEM SOFTWARE In evaluating the suitability of a system software following factors should be considered The type of computer required for using a given system software The types of applications that can run on a system software Ease of learning and using a system software Extent to which multiple users on networks can use the system software Extent of multitasking capabilities Reliability of a system software Cost of installation • SELECTION OF APPLICATION SOFTWARE Can be developed in-house or acquired from the market
- 41. PROCESS OF ACQUIRING HARDWARE /SOFTWARE 1. Determination of hardware/software required 2. Request for proposal 3. Proposal evaluation 4. Finalization of Hardware/software and vendor 5. Final approval and acquisition
- 42. INSTALLATION It involves 1. SITE PREPARATION: Appropriate location must be found that provides conductive operating environment for the system with prescribed temperature, humidity, dust control. • Site layout should be planned • Air conditioning equipment should be provided 2. EQUIPMENT INSTALLATION 3. EQUIPMENT CHECKUP
- 43. CONVERSION It’s a process of changing over from the existing system to the new system CONVERSION STRATEGIES 1. PARALLEL CONVERSION: • Possibility of checking new data against new data in order to catch errors in processing in new system • Offers a feeling of security to the users • Incur the cost of running both the systems together virtually doubling the work load during the conversion process. • The employees tend to stick to the old system because of their familiarity with it • There is a risk of higher resistance 2. DIRECT CONVERSION • There is no need of using both the systems • It is a risky process, until the new system has been tested properly in all respects
- 44. Contd.. 3. MODULAR CONVERSION: building modular prototypes to change from old system to the new system in a gradual manner • Each module is thoroughly tested before being used and users become familiar with each module as it becomes operational • Sometimes prototypes do not work in real operating conditions with the same efficiency as these would have worked during the testing time 4. PHASED CONVERSION: old system is converted into a new in phases • This phasing might be function wise or unit wise • New system can be tested at a small area and when it is successful it can be applied to other areas. This reduces the burden of errors caused. • If all the units of an organization are not similar the system working efficiently in one unit may not function with same efficiency in a u it which is different
- 45. ACTIVITIES INVOLVED IN CONVERSION • PROCEDURE CONVERSION: involves changing the procedure of the old system to the procedures of the new system. Procedures must be developed for data input, data files, operating method, outputs and internal control • FILE CONVERSION: capturing data and creating computer files from existing files • SYSTEM CONVERSION: after online and off-line files have been converted and reliability of the new system has been confirmed, daily data processing can be shifted to the new system • SCHEDULING EQUIPMENT AND PERSONNEL • ALTERNATIVE PLANS IN CASE OF SYSTEM FAILURE