(PCS-1002)MANAGEMENT INFORMATION SYSTEMMODULE-I

FUNDAMENTALS OF INFORMATION SYSTEM

IntroductionWhat is information system?

IS (information system) is the collection of technical and human resources that provide the storage, computing, distribution, and communication for the information required by all or some part of an enterprise . A special form of Information System is a management information system (MIS), which provides information for managing an enterprise.

It is a organized combination of hardware, software, infrastructure and trained personnel organized to facilitate planning, control, coordination, and decision making in an organization.Information technologies: The terms information system and information technologies are two different concepts. Information technology refers to different hardware components necessary for system to operate. Information systems could use these hardware components to capture and store its data. So we will concentrate on computer based information system and their use of following information technologies: Computer Hardware technologies including microcomputers, midsize servers, and large mainframe systems and the input, output and storage devices that support them.

Computer Software technologies including operating system software, web browsers, software productivity suites and software for business applications like customer relationship management and supply chain management.

Data Resource Management technologies emphasizes management of the data resources of computer-using organizations. It reviews on database management system software for the development, access and maintenance of the database of an organization. Telecommunications and Networks technologies including the telecommunications media, processors and software needed to provide wire-based and wireless access and support for the internet and private internet based networks such as intranets and extranets.An information system framework for business professionals

Figure illustrates a useful conceptual framework that organizes the knowledge presented in this text and outlines areas of knowledge you need about information systems. It emphasizes that you should concentrate your efforts in the following five areas of IS knowledge: Foundation Concepts. Fundamental behavioral, technical, business, and managerial concepts about the components and roles of information systems. Examples include basic information system concepts derived from general systems theory or competitive strategy concepts used to develop business applications of information technology for competitive advantage

Information Technologies. Major concepts, developments, and management issues in information technologythat is, hardware, software, networks, data management, and many Internet-based technologies.

Business Applications. The major uses of information systems for the operations, management, and competitive advantage of a business.

Development Processes. How business professionals and information specialists plan, develop, and implement information systems to meet business opportunities.MAJOR ROLE OF INFORMATION SYSTEM IN BUSINESSThere are three fundamental reasons for all business applications of information technology. They are found in the three vital roles that information systems can perform for a business enterprise: Support of business processes and operations.

Support of decision making by employees and managers.

Support of strategies for competitive advantage.

Trends in information systems:

Until the 1990s, the role of information systems was simple, transaction processing, record-keeping, accounting, and other electronic data processing (EDP) applications. Then another role was added, as the concept of management information system (MIS) was conceived. This new role focused on providing managerial end users with predefined management reports that would give managers the information they needed for decision making purposes.

By the 1970s, it was evident that the pre-specified information products produced by such management information systems were not adequately meeting many of the (DSS) was born. The new role for information systems was to provide managerial end users with ad hoc and interactive support of their decision-making processes.

In the 1980s, several new roles for information systems appeared. First, the rapid development of microcomputer processing power, application software packages, and telecommunications networks give birth to the phenomenon of end user computing. Now, end users can use their own computing resources to support their job requirements instead of waiting for the indirect support of corporate information services departments.

Second, it became evident that most top corporate executives did not directly use either the reports of information reporting systems or the analytical modeling capabilities of decision support systems, so the concept of executive information systems (EIS) was developed. These information systems attempt to give top executives an easy way to get the critical information they want, when they want it, tailored to the formats they prefer.

Third, breakthrough s occurred in the development and application of artificial intelligence (AI) techniques to business information systems. Expert systems can serve as consultants to users by providing expert advice in limited subject areas.

An important new role for information systems appeared in the 1980s and continues into the 1990s. This is the concept of a strategic role for information systems, sometimes called strategic information systems (SIS). In this concept, information technology becomes an integral component of business processes, products, and services that help a company gain a competitive advantage in the global marketplace.

Finally, the rapid growth of the Internet, intranets, extranets, and other interconnected global networks in the 1990s is dramatically changing the capabilities of information systems in business as we move into the next century. Such enterprise and global internetworking is revolutionizing end user, enterprise, and inter organizational computing, communications, and collaboration that supports the business operations and management of successful global enterprises.

DATA AND INFORMATION:DATA VERSUS INFORMATION

The word data is the plural of datum, though data commonly represents both singular and plural forms. Data are raw facts or observations, typically about physical phenomena or business transactions. For example, a spacecraft launch or the sale of an automobile would generate a lot of data describing those events. More specifically, data are objective measurements of the attributes (the characteristics) of entities (such as people, places, things, and events).Example

A spacecraft launch generates vast amounts of data. Electronic transmissions of data (telemetry) form thousands of sensors are converted to numeric and text data by computers.

Voice and image data are also captured through video and radio monitoring of the launch by mission controllers. Of course, buying a car or an airline ticket also produces a lot of data. Just think of the hundreds of facts needed to describe the characteristics of the car you want and its financing, or the details for even the simplest airline reservation.

Peoples often use the terms data and information interchangeably. However, it is better to view data as raw material resources that are processed into finished information products. Then we can define information as data that have been converted into a meaningful and useful context for specific end users. Thus, data are usually subjected to a value-added process (we call data processing or information processing) where (1) Its form is aggregated, manipulated, and organized; (2) its content is analyzed and view information as processed data placed in a context for human user. So you should view information as processed data placed in a context that gives it value for specific end users.Example

Names, quantities, and dollar amounts recorded on sales forms represent data about sales transactions. However, a sales manager may not regard these as information. Only after such facts are properly organized and manipulated can meaningful sales information be furnished, specifying, for example, the amount of sales by product type, sales territory, or sales persons.Three basic components of information system:

Input involves capturing and assembling elements that enter the system to be processed. For example, raw materials, energy, data, and human efforts must be secured and organized for processing.

Processing involves transformation process that converts input into output. Examples are a manufacturing process, the human breathing process, or mathematical calculations.

OutputIt involves transferring elements that have been produced by a transformation process to their ultimate destination. For example, finished products, human services, and management information must be transmitted to their human users.

ExampleA manufacturing system accepts raw materials as input and produces finished goods as output. An information system also is a system that accepts resources (data) as input and processes them into products (information) as output. FEEDBACK AND CONTROL

A system with feedback and control components is sometimes called a cybernetic system, that is, a self-monitoring, self-regulating system.

Feedback is data about the performance of a system. For example, data about sales performance is feedback to a

Control involves monitoring and evaluating feedback to determine whether a system is moving toward the achievement of its goal. The control function then makes necessary adjustments to a systems input and processing components to ensure that it produces proper output. For example, a sales manager exercises control when he or she reassigns salespersons to new sales territories after evaluating feedback about their sales performance.Feedback is frequently included as part of the concept of the control function because it is such a necessary part of its

Example

A familiar example of a self-monitoring, self-regulating system is the thermostat controlled heating system found in many homes; it automatically monitors and regulates itself to maintain a desired temperature. Another example is the human body, which can be regarded as cybernetic system that automatically monitors and adjusts many of its functions, such as temperature, heartbeat, and breathing.

OTHER SYSTEM CHARACTERISTICS

A system does not exist in a vacuum; rather, it exists and functions in and environment containing other systems. If a system is one of the components of a larger system, it is a subsystem, and the larger system in environment. Also, its environment and its system boundary separate a system from its environment and other systems.

Example

Organizations such as businesses and government agencies are good examples of the systems in society, which is their environment. Society contains a multitude of such systems, including individuals and their social, political, and economic institutions. Organizations themselves consist of many subsystems, such as departments, divisions, process teams, and other workgroups. Organizations are examples of open systems because they interface and interact with other systems in their environment. Finally, organizations are examples of adaptive systems, since they can modify themselves to meet the demands of a changing environment.COMPONENTS OF INFORMATION SYSTEMS:

COMPONENTS OF INFORMATION SYSTEMCOMPONENTS OF AN INFORMATION SYSTEM

An information system is a system that accepts data resources as input and processes them into information products as output. An information system depends on the resources of people (end users and IS specialists), hardware (machines and media), software (programs and procedures), data (data and knowledge basis), and networks (communications media and network support) to perform input, processing, output, storage, and control activities that convert data resources into information products.

This information system model highlights the relationships among the components and activities of information systems. It provides a framework that emphasizes four major concepts that can be applied to all types of information systems:

People, hardware, software, data, and networks are the five basic resources of information systems.

A people resource include end users and IS specialists, hardware resources consist of machines and media, software resources include both programs and procedures, data resources can include data and knowledge bases, and network resources include communications media and networks. Data resources are transformed by information processing activities into a variety of information products for end users. Information processing consists of input, processing, output, storage, and control activities.1) PEOPLE RESOURCES

People are required for the operation of all information systems. This people resource includes end users and IS specialists.

End users (also called users or clients) are people who use an information system or the information it produces. They can be accountants, salespersons, engineers, clerks, customers, or managers. Most of us are information system end users.

IS Specialists are people who develop and operate information systems. They include systems analysts, programmers, computer operators, and other managerial technical, and clerical IS personnel.

Briefly, systems analysts design information systems based on the information requirements of end users, programmers prepare computer programs based on the specifications of systems analysts, and computer operators operate large computer systems.2) HARDWARE RESOURCES

The concept of Hardware resources includes all physical devices and materials used in information processing. Specially, it includes not only machines, such as computers and other equipment, but also all data media, that is, all tangible objects on which data is recorded, from sheets of paper to magnetic disks.

Example of hardware in computer-based information systems are:

Computer systems, which consist of central processing units containing microprocessors, and variety of interconnected peripheral devices.Examples are microcomputer systems, midrange computer systems, and large mainframe computer systems.

Computer peripherals, which are devices such as a keyboard or electronic mouse for input of data and commands, a video screen or printer for output of information, and magnetic or optical disks for storage of data resources.

3) SOFTWARE RESOURCES The concept of Software Resources includes all sets of information processing instructions. This generic concept of software includes not only the sets of operating instructions called programs, which direct and control computer hardware, but also the sets of information processing instructions needed by people called procedures.

It is important to understand that even information systems that dont use computers have a software resource component. This is true even for the information systems of ancient times, or the manual and machine-supported information systems still used in the world today. They all require software resources in the form of information processing instructions and procedures in order to properly capture, process, and disseminate information to their users.

The following are the examples of software resources:

System Software, such as an operating system program, which con controls and supports the operations of a computer system.

Application Software, which are programs that direct processing for a particular use of computers by end users. Examples are a sales analysis program, a payroll program, and a word processing program. Procedures, which are operating instructions for the people who will use an information system. Examples are instructions for filling out a paper form or using a software package.4) DATA RESOURCES

Data is more than the raw material of information systems. The concept of data resources has been broadened by managers and information systems professionals. They realize that data constitutes a valuable organization resource. Thus, you should view data as data resources that must be managed effectively to benefit all end users in an organization. Data can take many forms, including traditional alphanumeric data, composed of numbers and alphabetical and other characters that describe business transactions and other events and entities.

Text data, consisting of sentences and paragraphs used in written communications; image data, such as graphic shapes and figures; and audio data, the human voice and other sounds, are also important forms of data.The data resources of information systems are typically organized into:

Database that hold processed and organized data.

Knowledge bases that hold knowledge in variety of forms such as facts, rules, and case examples about successful business practices.

For example, data about sales transactions may be accumulated and stored in a sales database for subsequent processing that yields daily, weekly, and monthly sales analysis reports for management. Knowledge bases are used by knowledge management systems and expert systems to share knowledge and give expert advice on specific subjects.DATA VERSUS INFORMATION

The word data is the plural of datum, though data commonly represents both singular and plural forms. Data are raw facts or observations, typically about physical phenomena or business transactions. For example, a spacecraft launch or the sale of an automobile would generate a lot of data describing those events. More specifically, data are objective measurements of the attributes (the characteristics) of entities (such as people, places, things, and events).Example

A spacecraft launch generates vast amounts of data. Electronic transmissions of data (telemetry) form thousands of sensors are converted to numeric and text data by computers.

Voice and image data are also captured through video and radio monitoring of the launch by mission controllers. Of course, buying a car or an airline ticket also produces a lot of data. Just think of the hundreds of facts needed to describe the characteristics of the car you want and its financing, or the details for even the simplest airline reservation.

Peoples often use the terms data and information interchangeably. However, it is better to view data as raw material resources that are processed into finished information products. Then we can define information as data that have been converted into a meaningful and useful context for specific end users. Thus, data are usually subjected to a value-added process (we call data processing or information processing) where (1) Its form is aggregated, manipulated, and organized; (2) its content is analyzed and view information as processed data placed in a context for human user. So you should view information as processed data placed in a context that gives it value for specific end users.Example

Names, quantities, and dollar amounts recorded on sales forms represent data about sales transactions. However, a sales manager may not regard these as information. Only after such facts are properly organized and manipulated can meaningful sales information be furnished, specifying, for example, the amount of sales by product type, sales territory, or sales persons.5) NETWORK RESOURCES

Telecommunications networks like the Internet, intranets, and extranets have become essential to the successful operations of all types of organizations and their computer-based information systems. Telecommunications networks consist of computers, communications processors, and other devices interconnected by communications media and controlled by communications software. The concept of Network resources emphasizes that communications networks are a fundamental resource component of all information systems. Network resources include: Communication media, Examples include twisted pair wire, coaxial cable, fiber-optic cable, microwave systems, and communication satellite systems.

Network Support, This generic category includes all of the people, hardware, software, and data resources that directly support the operation and use of a communications network. Examples include communications control software such as network operating systems and Internet packages.

INFORMATION SYSTEM ACTIVITIES

You should be able to recognize input, processing, output, storage and control activities taking place in any information system you are studying.

i. INPUT OF DATA RESOURCE

Data about business transactions and other events must be captured and prepared for processing by the input activity. Input typically takes the form of data entry activities such as recording and editing. End users typically record data about transactions on some type of physical medium such as paper form, or enter it directly into a computer system. This usually includes a variety of editing activities to ensure that they have recorded data correctly. Once entered, data may be transferred onto a machine-readable medium such as a magnetic disk until needed for processing.

For example, data about sales transactions can be recorded on source documents such as paper sales order forms. (A source document is the original formal record of a transaction). Alternately, salespersons can capture sales data using computer keyboards or optical scanning devices; they are visually prompted to enter data correctly by video displays. This provides them with a more convenient and efficient user interface, that is, methods of end user input and output with a computer system. Methods such as optical scanning and displays of menus, prompts, and fill-in-the-blanks formats make it easier for end users to enter data correctly into an information system.ii. PROCESSING OF DATA INTO INFORMATION

Data is typically subjected to processing activities such as calculating, comparing, sorting, classifying, and summarizing. These activities organize, analyze and manipulate data, thus converting them into information for end users. The quality of any data stored in an information system must also be maintained by a continual process of correcting and updating activities.For example, data received about a purchase can be (1) Added to a running total of sales results, (2) compared to a standard to determine eligibility for a sales discount, (3) sorted in numerical order based on product identification numbers, (4) classified into product categories (such as food and nonfood items), (5) summarized to provide a sales manager with information about various product categories, and finally, (6) used to update sales recordsiii. OUTPUT OF INFORMATION PRODUCTS

Information in various forms is transmitted to end-users and made available to them in the output activity. The goal of information systems is the production of appropriate information products for end users. Common information products messages, reports, forms, and graphic images, which may be provided by video displays, audio responses, paper products, and multimedia. For example, a sales manager may view a video display to check on the performance of a salesperson, accept a computer-produced voice message by telephone, and receive a printout of monthly sales results.iv. STORAGE OF DATA RESOURCE

Storage is a basic system component of information systems. Storage is the information system activity in which data and information are retained in an organized manner for later use. For example, just as written text material is organized into words, sentences, paragraphs, and documents; stored data is commonly organized into fields, records, files, and database. This facilitates its later use in processing or its retrieval as output when needed by users of a system.

v. CONTROL OF SYSTEM PERFORMANCE

An important information system activity is the control of its performance. An information system should produce feedback about its input, processing, output, and the system is meeting established performance standards. Then appropriate system activities must be adjusted so that proper information products are produced for end users.

For example, a manager may discover that subtotals of sales amounts in a sales report do not add up to total sales. This might mean that data entry or processing procedures need to be corrected. Then changes would have to be made to ensure that all sales transactions would be properly captured and processed by a sales information system.RECOGNIZING INFORMATION SYSTEM

There are many kinds of information systems in the real world. All of them use hardware, software, network, and people resources to transform data resources into information products. Some are simple manual information systems, where people use simple tools such as pencils and paper, or even machines such as calculators and typewriters. Others are computer based information systems that rely on a variety of networked computer systems to accomplish their information processing activities. As business end user, you should be able to recognize the fundamental components of information systems you encounter in the real world. This means that you should be able to identify:

i. The people, hardware, software, data, and network resources they use.

ii. The type of information products they produce.

iii. The way they perform input, processing, output, storage and control activities.

iv. How they support the business operations, managerial decision-making, or competitive advantage of a business.This kind of understanding will help you be a better user, developer, and manager of information system.SYSTEM APPORACH IN PROBLEM SOLVING:INTRODUCTION:

A system can be defined as the orderly arrangement of set of interrelated and interdependent elements that operate collectively to accomplish common objective or goal.

The systems approach to problem solving used a systems orientation to define problems and opportunities and develop solutions. Studying a problem and formulating a solution involve the following interrelated activities:

1. Recognize and define a problem or opportunity using systems thinking.

2. Develop and evaluate alternative system solutions.

3. Select the system solution that best meets your requirements.

4. Design the selected system solution.

5. Implement and evaluate the success of the designed system.

1) Defining problems and opportunitiesProblems and opportunities are identified in the first step of the systems approach. A problem can be defined as a basic condition that is causing undesirable results. An opportunity is a basic condition that presents the potential for desirable results. Symptoms must be separated from problems. Symptoms are merely signals of an underlying cause or problem.

Example;

Symptom: Sales of a companys products are declining. Problem: Sales persons are losing orders because they cannot get current information on product prices and availability. Opportunity: We could increase sales significantly if sales persons could receive instant responses to requests for price quotations and product availability.

2) Systems thinkingSystems thinking is to try to find systems, subsystems, and components of systems in any situation your are studying. This viewpoint ensures that important factors and their interrelationships are considered. This is also known as using a systems context, or having a systemic view of a situation. I example, the business organization or business process in which a problem or opportunity arises could be viewed as a system of input, processing, output, feedback, and control components. Then to understand a problem and save it, you would determine if these basic system functions are being properly performed.

Example;

The sales function of a business can be viewed as a system. You could then ask: Is poor sales performance (output) caused by inadequate selling effort (input), out-of-date sales procedures (processing), incorrect sales information (feedback), or inadequate sales management (control)? Figure illustrates this concept.

3) Developing alternate solutionsThere are usually several different ways to solve any problem or pursue any opportunity. Jumping immediately from problem definition to a single solution is not a good idea. It limits your options and robs you of the chance to consider the advantages and disadvantages of several alternatives. You also lose the chance to combine the best points of several alternative solutions.

Where do alternative solutions come from/ experience is good source. The solutions that have worked, or at least been considered in the past, should be considered again. Another good source of solutions is the advice of others, including the recommendations of consultants and the suggestions of expert systems. You should also use your intuition and ingenuity to come up with a number of creative solutions. These could include what you think is an ideal solution. The, more realistic alternatives that recognize the limited financial, personnel, and other resources of most organizations could be developed. Also, decision support software packages can be used to develop and manipulate financial, marketing, and other business operations. This simulation process can help you generate a variety of alternative solutions. Finally, dont forget that doing nothing about a problem or opportunity is a legitimate solution, with its own advantages and disadvantages.

4) Evaluating alternate solutionsOnce alternative solutions have been developed, they must be evaluated so that the best solution can be identified. The goal of evaluation is to determine how well each alternative solution meets your business and personal requirements. These requirements are key characteristics and capabilities that you feed are necessary for your personal or business success.

Example;

If you were the sales manager of a company, you might develop very specific requirements for solving the sales-related information problems of your salespeople. You would probably insist that any computer-based solution for your sales force be very reliable and easy to use. You might also require that any proposed solution have low start-up costs, or have minimal operating costs compared to present sales processing methods.

Then you would develop evaluation criteria and determine how well each alternative solution meets these criteria. The criteria you develop will reflect how you previously defined business and personal requirements. For example, you will probably develop criteria for such factors as start-up costs, operating costs, ease of use, and reliability.

Criteria may be ranked or weighted, based on their importance in meeting your requirements.

5) Selecting the best solutionOnce all alternative solutions have been evaluated, you can being the process of selecting the best solution. Alternative solutions can be compared to each other because they have been evaluated using the same criteria.

Example;

Alternatives with a low accuracy evaluation (an accuracy score less than 10), or a low overall evaluation (an overall score less than 70) should be rejected.

Therefore, alternative B for sales data entry is rejected, and alternative A, the use of laptop computers by sales reps, is selected.

6) Designing and implementing solutionOnce a solution has been selected, it must be designed and implemented. You may have to depend on other business end users technical staff to help you develop design specifications and an implementation plan. Typically, design specifications might describe the detailed characteristics and capabilities of the people, hardware, software, and data resources and information system activities needed by a new system. An implementation plan specifies the resources, activities, and timing needed for proper implementation. For example, the following items might be included in the design specifications and implementation plan for a computer-based sales support system:

Types and sources of computer hardware, and software to be acquired for the sales reps.

Operating procedures for the new sales support system.

Training of sales reps and other personnel.

Conversion procedures and timetable for final implementation.

7)Post implementation reviewThe final step of the systems approach recognizes that an implemented solution can fail to solve the problem for which it was developed. The real world has a way of confounding even the well-designed solutions. Therefore, the results of implementing a solution should be monitored and evaluated. This is called a post-implemented. The focus of this step is to determine if the implemented solution has indeed helped the firm and selected subsystems meet their system objectives. If not, the systems approach assumes you will cycle back to a previous step and make another attempt to find a workable solution.

DEVELOPING INFORMATION SYSTEM SOLUTIONS:

THE TRADITIONAL INFORMATION SYSTEM DEVELOPMENT CYCLEStep 1: Recognition of Need What is the Problem?One must know what the problem is before it can be solved. The basis for a candidate system is recognition of a need for improving an information system or a procedure. For example, a supervisor may want to investigate the system flow in purchasing. Or a bank president has been getting complaints about the long lines in the drive in. This need leads to a preliminary survey or an initial investigation to determine whether an alternative system can solve the problem. It entails looking into the duplication of effort bottlenecks, inefficient existing procedures, or whether parts of the existing system would be candidates for computerization. If the problem is serious enough, management may want to have an analyst look at it, such an assignment implies a commitment, especially if the analyst hired from the outside. In larger environments, where formal procedures are the norm, the analysts first task is to prepare a statement specifying the scope and objective of the problem. He/she then reviews it with the user for accuracy at this stage, only a rough ball parle estimate of the development cost of the project may be reached. However, an accurate cost of the next phase the feasibility study can be produced.

Step 2: Feasibility StudyDepending on the results of the initial investigation, the survey is expanded to a more detailed feasibility study. As we shall learn, a feasibility study is a test of a system proposal according to its workability impact on the organization, ability to meet user needs, and effective use of resources. It focuses on there major questions:

What are the users demonstrable needs and how does a candidate system meet them?

What resources are available for given candidate systems? Is the problem worth solving?

What are the likely impact of the candidate system on the organization? How will it fit within the organizations master MIS plan?

Each of these questions must be answered carefully. They revolve around investigation and evaluation of the problem, identification and description of candidate systems, specification of performance and the cost of each system, and final selection of the best system.

The objective of a feasibility study is not to solve the problem but to acquire a sense of its scope. During the study, the problem definition is crystallized and aspects of the problem to be included in the system are determined. Consequently, costs and benefits are estimated with greater accuracy at this stage.

The result of the feasibility study is a formal proposal. This is simply a report a formal document detailing the nature and scope of the proposed solution. The proposal summarizes what is known and what is going to be done. It consists of the following.

1. Statement of the Problem a carefully worded statement of the problem that led to analysis.

2. Summary of Findings and Recommendations a list of the major findings and recommendations of the study. It is ideal for the user who required quick access to the results of the analysis of the system under study. Conclusions are stated, followed by a list of the recommendations and a justification for them.

3. Details of Findings An outline of the methods and procedures undertaken by the existing system, followed by coverage of objectives & procedures of the candidate system. Included are also discussions of output reports, file structures, and costs and benefits of the candidate system.

4. Recommendations and Conclusions special recommendations regarding the candidate system, including the personal assignments costs, project schedules, and target dates.

Three key considerations are involved in the feasibility analysis: economic, technical, behavioural. Lets briefly review each consideration and how it relates to the systems effort.

Economic Feasibility: Economic analysis is the most frequently used method for evaluating the effectiveness of a candidate system. More commonly known as cost/benefit analysis, the procedure is to determine the benefits and savings that are expected from a candidate system and compare them with costs. If benefits outweigh costs, then the decision is made to design and implement the system. Otherwise, further justification or alterations in the proposed system will have to be made if it is to have a chance of being approved. This is an ongoing effort that improves in accuracy at each phase of the system life cycle.

Technical Feasibility: Technical feasibility centers around the existing computer system (hardware, software etc.) and to what extent it can support the proposed addition. For example, if the current computer is operating at 80 per cent capacity an arbitrary ceiling then running another application could overload the system or require additional hardware. This involves financial considerations to accommodate technical enhancements. If the budget is a serious constraint, then the project is judged not feasible.

Behavioural Feasibility: People are inherently resistant to change, and computers have been known to facilitate change. An estimate should be made of how strong a reaction the user staff is likely to have towards the development of a computerized system. It is common knowledge that computer installations have something to do with turnover, transfers, retraining, and changes in employee job status. Therefore, it is understandable that the introduction of a candidate system requires special effort to educate, sell, and train the staff on new ways of conducting business.

After the proposal is viewed by management it becomes a formal agreement that paves the way for actual design and implementation. This is a crucial decision point in the life cycle. Many projects die here, whereas the more promising ones continue through implementation. Changes in the proposal are made in writing, depending on the complexity, size, and cost of the project. It is simply common sense to verify changes before committing the project to design.

Step 3: AnalysisIt is a detailed study of the various operations performed by the system and their relationship within and outside of the system. A key question is what must be done to solve the problem? One aspect of analysis is defining the boundaries of the system and determining whether or not a candidate system should consider other related systems. During analysis, data are collected on available files, decision points, and transactions handled by the present system. We shall learn about some logical system models and tools that are used in analysis. It requires special skills and sensitivity to the subjects being interviewed. Bias in data collection and interpretation can be problem. Training, experience and common sense are required for collection of the information needed to do the analysis. Once analysis is completed the analyst has a firm understanding of what is to be done. The next step is to decide how the problem might be solved. Thus, in the systems design, we move from the logical to the physical aspects of the life cycle.

Step 4: DesignThe most creative and challenging phase of the system life cycle is system design. The term design describes both a final system and a process by which it is developed. It refers to the technical specifications (analogous to the engineers blueprints) that will be applied in implementing the candidate system. It also includes the constructions of programs and programme testing. The key question here is How should the problem be solved?.

The first step is to determine how the output is to be produced and in what format. Samples of the output (and input) are also available. Second, input data and master files (data base) have to be designed to meet the requirements of the proposed output. The operational (processing) phase are handled through programe construction and testing, including a list of the programmes needed to meet the systems objectives and complete documentation. Finally, details related to justification of the system and an estimate of the impact of the candidate system on the user and the organization are documented and evaluated by management as a step toward implementation.

The final report prior to the implementation phase includes procedural flowcharts, record layouts, report layouts, and a workable plan for implementing the candidate system. Information on personnel, money, hardware, facilities and their estimated cost must also be available. At this point, projected costs must be close to actual costs of implementation.

In some firms, separate groups of programmer do the programming whereas other firms employ analyst programmers who do analysis and design as well as code programmes. For this discussion, we assume that analysis and programming is carried out by two separate persons. There are certain functions, though, that the analyst must perform while programes are being written operating procedures and documentation must be completed. Security and auditing procedures must also be developed.

Step 5: TestingNo system design is ever perfect. Communication problems, programmers negligence or time constraints create errors that most be eliminated before the system is ready for user acceptance testing. A system is tested for online response, volume of transactions, stress, recovery form failure and usability. Then comes system testing, which verifies that the whole set of programs hangs together, following system testing is acceptance testing or running the system with live data by the actual use.

System testing requires a test plan that consists of several key activities and steps for programs, string, system and user acceptance testing. The system performance criteria deal with turnaround time, backup, file protection, and the human factor.

Step 6: ImplementationThis phase is less creative than system design. It is primarily concerned with user training, site preparation, and file conversion. When the candidate system is linked to terminals and remote sites the telecommunication network and tests of the network along with the system are also included under implementation.

During the final testing, user acceptance is tested, followed by user training. Depending on the nature of the system, extensive user training may be required, conversion usually takes place at about the same time the user is being trained or later.

In the extreme, the programmer is falsely viewed as someone who ought to be isolated from other aspects of system development. Programming is itself design work, however. The initial parameter of the candidate system should be modified as a result of programming efforts. Programming provides a reality test for the assumptions made by the analyst. It is therefore a mistake to exclude programmers from the initial system design. System testing checks the readiness and accuracy of the system to access, update and retrieve data from new files. Once the programmes become available, test data are read into the computer and processed against the file(s) provided for testing. If successful, the program(s) is then run with live data. Otherwise, a diagnostic procedure is used to local and correct errors in the program. In most programs, a parallel run is conducted where the new system runs simultaneously with the old systems. This method, though costly, provides added assurance against errors in the candidate system and also gives the user-staff an opportunity to gain experience through operation. In some cases, however, parallel processing is not practical. For example, it is not plausible to run two parallel online point-to-sale (POS) systems for a retail chain. In any case, after the candidate system proves itself, the old system is phased out.

Step 7: EvaluationDuring systems testing, the system is used experimentally to ensure that the software does not fail. In other words, we can say that it will run according to its specifications and in the way users expect. Special test data are input for processing, and the results examined. A limited number of users may be allowed to use the system so that analyst can see whether to use it in unforeseen ways. It is desirable to discover any surprises before the organization implements the system and depends on it.

Implementation is the process of having systems personnel check out and put new equipment into use, train users, install the new application and construct any files of data needed to use it. This phase is less creative than system design. Depending on the size of the organisation that will be involved in using the application and the risk involved in its use, systems developers may choose to test the operation in only one area of the Firm with only one or two persons. Sometimes, they will run both old and new system in parallel way to compare the results. In still other situations, system developers stop using the old system one day and start using the new one the next.

Evaluation of the system is performed to identify its strengths and weaknesses. The actual evaluation can occur along any one of the following dimensions:

Operational Evaluation: Assessment of the manner in which the system functions, impact.

Organizational Impact: Identification and measurement of benefits to the organisation in such areas as financial concerns, operational efficiency and competitive impact.

User Manager Assessment: Evaluation of the attitudes of senior and user manager within the organisation, as well as end-users.

Development Performance: Evaluation of the development process in accordance with such yardsticks as overall development time and effort, conformance to budgets and standards and other project management criteria.

Step 8: Post Implementation and MaintenanceMaintenance is necessary to eliminate errors in the working system during its working life and to tune the system to any variations in its working environment. Often small system deficiencies are found as a system is brought into operation and changes are made to remove them. System planners must always plan for resource availability to carry out these maintenance functions. The importance of maintenance is to continue to bring the new system to standards.

After the installation phase is completed and the user staff is adjusted to changes created by the candidate system, evaluation and maintenance being. Like any system there is an ageing process the requires periodic maintenance of hardware & software. If the new information is inconsistent with the design specifications, then changes have to be made. Hardware also requires periodic maintenance to keep in time with design specification. The importance of maintenance is to continue to bring the new system to standards.CASE STUDY-1

Roberts Company is a worldwide leader in financial management and employing 50, people in 36 countries and territories. It is into brokerage, investment banking, financing, wealth management, advisory, asset management, insurance, lending, and other related products and services to private, institutional, and government clients with assets of $1.6 trillion. Over the last five years, that IT infrastructure has played a major role in the companys gains. Like many financial institutions, Roberts Company has had to modernize its technology infrastructure in order to remain competitive. In modernizing its technology, Roberts Company had to make choices regarding its legacy computers and applications. Internet-based applications that gave customers access to their portfolios and tools to work with them were a key to remaining competitive. But these applications did not use mainframe-based software. Roberts Company had initially tried to avoid the costs by copying the data stored in its mainframe installation into Oracle, Sybase, or Microsoft SQL Server databases. In those formats, the data were compatible with server-based applications. However, that technique was not entirely satisfactory. Copying large quantities of data often introduces errors based on disk failures and space issues. The project team prohibited the new platform from requiring changes to program code on the mainframe or hindering its operation in any respect. The team did not want to alter the mainframe in any way because of its track record, its complexity, and the fact that there was likely no one on staff who knew the inner workings of its deep-rooted code.

Case Questions1. Why did the firm need to update its IT infrastructure?

2. What is the relationship of information technology to Robert Companys business strategy?MODULE-II

CORPORATE DATABASEIntroduction:

Corporate DatabaseCorporate database is the data related to any enterprise from starting the enterprise to the wind up off. It contains all the information related to all the activities of any business. It contains the data about the history of related industry.

All the activities of any firm from the starting to wind up about what the corporate database is related

1. At the time of initializing: When any business started by entrepreneur then it becomes very important to get the information related to legal requirements and registration related formalities. Corporate database collect all the data related to these terms at beginning.

a. Legal requirement to start a business

b. Mission and Vision statement

c. Goal and objectives of the business

d. Principles of the organization

e. Expansion and diversification related database

2. At the time of operation: When business comes in operation then all the database is maintained related to operation. Business is divided into departments for proper control over activities and database is also maintained according to these departmental activities i.e. Finance, Marketing, Production, Human Resource etc. Some information related to these activities are

a. Accounts of business

b. Employee database

c. Departments database

d. Competitors database

e. Growth database

Corporate database helps entrepreneur and managers to take better decisions and for proper controlling over market related activities.

Data organization

Data are the principal resources of an organization. Data stored in computer systems form a hierarchy extending from a single bit to a database, the major record-keeping entity of a firm. Each higher rung of this hierarchy is organized from the components below it.

Data are logically organized into:

1. Bits (characters)

2. Fields

3. Records

4. Files

5. Databases

Bit (Character) - a bit is the smallest unit of data representation (value of a bit may be a 0 or 1). Eight bits make a byte which can represent a character or a special symbol in a character code.

Field - a field consists of a grouping of characters. A data field represents an attribute (a characteristic or quality) of some entity (object, person, place, or event).

Record - a record represents a collection of attributes that describe a real-world entity. A record consists of fields, with each field describing an attribute of the entity.

File - a group of related records. Files are frequently classified by the application for which they are primarily used (employee file). A primary key in a file is the field (or fields) whose value identifies a record among others in a data file.

Database - is an integrated collection of logically related records or files. A database consolidates records previously stored in separate files into a common pool of data records that provides data for many applications. The data is managed by systems software called database management systems (DBMS). The data stored in a database is independent of the application programs using it and of the types of secondary storage devices on which it is stored.File Organization Terms and Concepts Entity: Person, place, thing, event about which information is maintained Attribute: Description of a particular entity Key field: Identifier field used to retrieve, update, sort a record

There are three principal methods of organizing files, of which only two provide the direct access necessary in on-line systems.

File Organization Data files are organized so as to facilitate access to records and to ensure their efficient storage. A tradeoff between these two requirements generally exists: if rapid access is required, more storage is required to make it possible.

Access to a record for reading it is the essential operation on data. There are two types of access:

1. Sequential access - is performed when records are accessed in the order they are stored. Sequential access is the main access mode only in batch systems, where files are used and updated at regular intervals.

2. Direct access - on-line processing requires direct access, whereby a record can be accessed without accessing the records between it and the beginning of the file. The primary key serves to identify the needed record.

There are three methods of file organization: [Table 6.1]

1. Sequential organization

2. Indexed-sequential organization

3. Direct organization

Sequential OrganizationIn sequential organization records are physically stored in a specified order according to a key field in each record.

Advantages of sequential access:

1. It is fast and efficient when dealing with large volumes of data that need to be processed periodically (batch system).

Disadvantages of sequential access:

1. Requires that all new transactions be sorted into the proper sequence for sequential access processing.

2. Locating, storing, modifying, deleting, or adding records in the file requires rearranging the file.

3. This method is too slow to handle applications requiring immediate updating or responses.

Indexed-Sequential OrganizationIn the indexed-sequential files method, records are physically stored in sequential order on a magnetic disk or other direct access storage device based on the key field of each record. Each file contains an index that references one or more key fields of each data record to its storage location address.

Direct OrganizationDirect file organization provides the fastest direct access to records. When using direct access methods, records do not have to be arranged in any particular sequence on storage media. Characteristics of the direct access method include:

1. Computers must keep track of the storage location of each record using a variety of direct organization methods so that data can be retrieved when needed.

2. New transactions' data do not have to be sorted.

3. It is a Processing that requires immediate responses or updating is easily performed.

TRADITIONAL FILE STRUCTURE:Traditional file based system is basically a file based system, in which we manually or through computer handle the database such as updating, insertion ,deletion adding new files to database etc.

File processing systems was an early attempt to computerize the manual filing system that we are all familiar with. A file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. File systems may use a storage device such as a hard disk or CD-ROM and involve maintaining the physical location of the files.In our own home, we probably have some sort of filing system, which contains receipts, guarantees, invoices, bank statements, and such like. When we need to look something up, we go to the filing system and search through the system starting from the first entry until we find what we want. Alternatively, we may have an indexing system that helps to locate what we want more quickly. For example we may have divisions in the filing system or separate folders for different types of item that are in some way logically related.

The manual filing system works well when the number of items to be stored is small. It even works quite adequately when there are large numbers of items and we have only to store and retrieve them. However, the manual filing system breaks down when we have to cross-reference or process the information in the files. For example, a typical real estate agent's office might have a separate file for each property for sale or rent, each potential buyer and renter, and each member of staff.

Clearly the manual system is inadequate for this' type of work. The file based system was developed in response to the needs of industry for more efficient data access. In early processing systems, an organization's information was stored as groups of records in separate files.

In the traditional approach, we used to store information in flat files which are maintained by the file system under the operating system's control. Here, flat files are files containing records having no structured relationship among them. The file handling which we learn under C/C ++ is the example of file processing system. The Application programs written in C/C ++ like programming languages go through the file system to access these flat files as shown.

Characteristics of File Processing System

Here is the list of some important characteristics of file processing system:

It is a group of files storing data of an organization.

Each file is independent from one another.

Each file is called a flat file.

Each file contained and processed information for one specific function, such as accounting or inventory.

Files are designed by using programs written in programming languages such as COBOL, C, C++.

The physical implementation and access procedures are written into database application; therefore, physical changes resulted in intensive rework on the part of the programmer.

As systems became more complex, file processing systems offered little flexibility, presented many limitations, and were difficult to maintain. Limitations of the File Processing System I File-Based Approach

There are following problems associated with the File Based Approach:

1. Separated and Isolated Data: To make a decision, a user might need data from two separate files. First, the files were evaluated by analysts and programmers to determine the specific data required from each file and the relationships between the data and then applications could be written in a programming language to process and extract the needed data. Imagine the work involved if data from several files was needed.

2. Duplication of data: Often the same information is stored in more than one file. Uncontrolled duplication of data is not required for several reasons, such as:

Duplication is wasteful. It costs time and money to enter the data more than once

It takes up additional storage space, again with associated costs.

Duplication can lead to loss of data integrity; in other words the data is no longer consistent. For example, consider the duplication of data between the Payroll and Personnel departments. If a member of staff moves to new house and the change of address is communicated only to Personnel and not to Payroll, the person's pay slip will be sent to the wrong address. A more serious problem occurs if an employee is promoted with an associated increase in salary. Again, the change is notified to Personnel but the change does not filter through to Payroll. Now, the employee is receiving the wrong salary. When this error is detected, it will take time and effort to resolve. Both these examples, illustrate inconsistencies that may result from the duplication of data. As there is no automatic way for Personnel to update the data in the Payroll files, it is difficult to foresee such inconsistencies arising. Even if Payroll is notified of the changes, it is possible that the data will be entered incorrectly.

3. Data Dependence: In file processing systems, files and records were described by specific physical formats that were coded into the application program by programmers. If the format of a certain record was changed, the code in each file containing that format must be updated. Furthermore, instructions for data storage and access were written into the application's code. Therefore, .changes in storage structure or access methods could greatly affect the processing or results of an application.

In other words, in file based approach application programs are data dependent. It means that, with the change in the physical representation (how the data is physically represented in disk) or access technique (how it is physically accessed) of data, application programs are also affected and needs modification. In other words application programs are dependent on the how the data is physically stored and accessed.

If for example, if the physical format of the master/transaction file is changed, by making he modification in the delimiter of the field or record, it necessitates that the application programs which depend on it must be modified.

Let us consider a student file, where information of students is stored in text file and each field is separated by blank space as shown below:

I Rahat 35 Thapar

Now, if the delimiter of the field changes from blank space to semicolon as shown below:

1; Rahat; 35; Thapar

Then, the application programs using this file must be modified, because now it will token the field on semicolon; but earlier it was blank space.

4. Difficulty in representing data from the user's view: To create useful applications for the user, often data from various files must be combined. In file processing it was difficult to determine relationships between isolated data in order to meet user requirements.

5. Data Inflexibility: Program-data interdependency and data isolation, limited the flexibility of file processing systems in providing users with ad-hoc information requests

6. Incompatible file formats: As the structure of files is embedded in the application programs, the structures are dependent on the application programming language. For example, the structure of a file generated by a COBOL program may be different from the structure of a file generated by a 'C' program. The direct incompatibility of such files makes them difficult to process jointly.

7. Data Security. The security of data is low in file based system because, the data is maintained in the flat file(s) is easily accessible. For Example: Consider the Banking System. The Customer Transaction file has details about the total available balance of all customers. A Customer wants information about his account balance. In a file system it is difficult to give the Customer access to only his data in the file. Thus enforcing security constraints for the entire file or for certain data items are difficult.

8. Transactional Problems. The File based system approach does not satisfy transaction properties like Atomicity, Consistency, Isolation and Durability properties commonly known as ACID properties.

For example: Suppose, in a banking system, a transaction that transfers Rs. 1000 from account A to account B with initial values' of A and B being Rs. 5000 and Rs. 10000 respectively. If a system crash occurred after the withdrawal of Rs. 1000 from account A, but before depositing of amount in account B, it will result an inconsistent state of the system. It means that the transactions should not execute partially but wholly. This concept is known as Atomicity of a transaction (either 0% or 100% of transaction). It is difficult to achieve this property in a file based system.

9. Concurrency problems. When multiple users access the same piece of data at same interval of time then it is called as concurrency of the system. When two or more users read the data simultaneously there is ll( problem, but when they like to update a file simultaneously, it may result in a problem.

10. Poor data modeling of real world. The file based system is not able to represent the complex data and interfile relationships, which results poor data modeling properties.DATABASE MANAGEMENT SYSTEMDatabase approach is a computer based storage technology in which related data is shared by various application programs. It is an improvement of traditionally file-based approach of storing data or information. It is characterized by a database management system and one or more databases.

The Database is a shared collection of logically related data, designed to meet the information needs of an organization. A database is a computer based record keeping system whose over all purpose is to record and maintains information. The database is a single, large repository of data, which can be used simultaneously by many departments and users. Instead of disconnected files with redundant data, all data items are integrated with a minimum amount of duplication.

The database is no longer owned by one department but is a shared corporate resource. The database holds not only the organization's operational data but also a description of this data. For this reason, a database is also defined as a self-describing collection of integrated records. The description of the data is known as the Data Dictionary or Meta Data (the 'data about data'). It is the self-describing nature of a database that provides program-data independence.

FEATURES: Creates and maintains databases Eliminates requirement for data definition statements Acts as interface between application programs and physical data files Separates logical and physical views of dataA database implies separation of physical storage from use of the data by an application program to achieve program/data independence. Using a database system, the user or programmer or application specialist need not know the details of how the data are stored and such details are "transparent to the user". Changes (or updating) can be made to data without affecting other components of the system. These changes include, for example, change of data format or file structure or relocation from one device to another.

In the DBMS approach, application program written in some programming language like Java, Visual Basic.Net, and Developer 2000 etc. uses database connectivity to access the database stored in the disk with the help of operating system's file management system.

The file system interface and DBMS interface for the university management system is shown.

Building blocks of a Database

The following three components form the building blocks of a database. They store the data that we want to save in our database.

Columns. Columns are similar to fields, that is, individual items of data that we wish to store. A Student' Roll Number, Name, Address etc. are all examples of columns. They are also similar to the columns found in spreadsheets (the A, B, C etc. along the top).

Rows. Rows are similar to records as they contain data of multiple columns (like the 1, 2, 3 etc. in a spreadsheet). A row can be made up of as many or as few columns as you want. This makes reading data much more efficient - you fetch what you want.

Tables. A table is a logical group of columns. For example, you may have a table that stores details of customers' names and addresses. Another table would be used to store details of parts and yet another would be used .for supplier's names and addresses.

It is the tables that make up the entire database and it is important that we do not duplicate data at all.

Characteristics of database

The data in a database should have the following features:

Organized/Related. It should be well organized and related.

Shared. Data in a database are shared among different users and applications.

Permanent or Persistence. Data in a database exist permanently in the sense the data can live beyond the scope of the process that created it. Validity/integrity/Correctness. Data should be correct with respect to the real world entity that they represent.

Security. Data should be protected from unauthorized access.

Consistency. Whenever more than one data element in a database represents related real world values, the values should be consistent with respect to the relationship.

Non-redundancy: No two data items in a database should represent the same real world entity.

Independence. Data at different levels should be independent of each other so that the changes in one level should not affect the other levels.

Easily Accessible. It should be available when and where it is needed i.e. it should be easily accessible.

Recoverable. It should be recoverable in case of damage.

Flexible to change. It should be flexible to change.

To create, manage and manipulate data in databases, a management system known as database management system was developed.

Comparison of Traditional File-Based Approach and Database Approach

At the beginning, you should understand the rationale of replacing the traditional file-based system with the database system.

File-based System

File-based systems were an early attempt to computerize the manual filing system. File-based system is a collection of application programs that perform services for the end-users. Each program defines and manages its data.

However, five types of problem are occurred in using the file-based approach:

1. Separation and isolation of data

When data is isolated in separate files, it is more difficult for us to access data that should be available. The application programmer is required to synchronize the processing of two or more files to ensure the correct data is extracted.

2. Duplication of data

When employing the decentralized file-based approach, the uncontrolled duplication of data is occurred. Uncontrolled duplication of data is undesirable because:

i.Duplication is wasteful

ii.Duplication can lead to loss of data integrity

3. Data dependence4. Using file-based system, the physical structure and storage of the data files and records are defined in the application program code. This characteristic is known as program-data dependence. Making changes to an existing structure are rather difficult and will lead to a modification of program. Such maintenance activities are time-consuming and subject to error.5. Incompatible file formats

The structures of the file are dependent on the application programming language. However file structure provided in one programming language such as direct file, indexed-sequential file which is available in COBOL programming, may be different from the structure generated by other programming language such as C. The direct incompatibility makes them difficult to process jointly.

Fixed queries / proliferation of application programs

File-based systems are very dependent upon the application programmer. Any required queries or reports have to be written by the application programmer. Normally, a fixed format query or report can only be entertained and no facility for ad-hoc queries if offered.

Database Approach:

In order to overcome the limitations of the file-based approach, the concept of database and the Database Management System (DMS) was emerged in 60s.

Advantages

A number of advantages of applying database approach in application system are obtained including:

1. Control of data redundancy

The database approach attempts to eliminate the redundancy by integrating the file. Although the database approach does not eliminate redundancy entirely, it controls the amount of redundancy inherent in the database.

2. Data consistency

By eliminating or controlling redundancy, the database approach reduces the risk of inconsistencies occurring. It ensures all copies of the data are kept consistent.

3. More information from the same amount of data

With the integration of the operated data in the database approach, it may be possible to derive additional information for the same data.

4. Sharing of data

Database belongs to the entire organization and can be shared by all authorized users.

5. Improved data integrity

Database integrity provides the validity and consistency of stored data. Integrity is usually expressed in terms of constraints, which are consistency rules that the database is not permitted to violate.

6. Improved security

Database approach provides a protection of the data from the unauthorized users. It may take the term of user names and passwords to identify user type and their access right in the operation including retrieval, insertion, updating and deletion.

7. Enforcement of standards

The integration of the database enforces the necessary standards including data formats, naming conventions, documentation standards, update procedures and access rules.

8. Economy of scale

Cost savings can be obtained by combining all organization's operational data into one database with applications to work on one source of data.

9. Balance of conflicting requirements

By having a structural design in the database, the conflicts between users or departments can be resolved. Decisions will be based on the base use of resources for the organization as a whole rather that for an individual entity.

10. Improved data accessibility and responsiveness :By having an integration in the database approach, data accessing can be crossed departmental boundaries. This feature provides more functionality and better services to the users.11. Increased productivity

The database approach provides all the low-level file-handling routines. The provision of these functions allows the programmer to concentrate more on the specific functionality required by the users. The fourth-generation environment provided by the database can simplify the database application development.

12. Improved maintenance

Database approach provides a data independence. As a change of data structure in the database will be affect the application program, it simplifies database application maintenance.

13. Increased concurrency

Database can manage concurrent data access effectively. It ensures no interference between users that would not result any loss of information nor loss of integrity.

14. Improved backing and recovery services

Modern database management system provides facilities to minimize the amount of processing that can be lost following a failure by using the transaction approach.DBMS Architecture:

1. External view: This is a highest level of abstraction as seen by user. This level of abstraction describes only the part of entire database. It is based on the conceptual model, is the end user view of data environment. Each external view described by means of a schema called an external schema or subschema.

2. Conceptual level: At this level of database abstraction all the database entities and the relationships among them are included. One conceptual view represents the entire database. the conceptual schema defines ths conceptual view.

3. Internal(physical) level : This lowest level of abstraction. it closest to physical storage device. It describes how data are actually stored on the storage medium. The internal schema, which contains the definition of the stored record, the method representing the data fields, expresses the internal view and the access aids used.

Data Independence:

1. The ability to modify a scheme definition in one level without affecting a scheme definition in a higher level is called data independence.

2. There are two kinds:

Physical data independence

The ability to modify the physical scheme without causing application programs to be rewritten

Modifications at this level are usually to improve performance

Logical data independence

The ability to modify the conceptual scheme without causing application programs to be rewritten

Usually done when logical structure of database is altered

3. Logical data independence is harder to achieve as the application programs are usually heavily dependent on the logical structure of the data. An analogy is made to abstract data types in programming languages. Components of DBMS

A database management system (DBMS) consists of several components. Each component plays very important role in the database management system environment. The major components of database management system are:

Software

Hardware

Data

Procedures

Database Access Language

SoftwareThe main component of a DBMS is the software. It is the set of programs used to handle the database and to control and manage the overall computerized database

1. DBMS software itself, is the most important software component in the overall system

2. Operating system including network software being used in network, to share the data of database among multiple users.

3. Application programs developed in programming languages such as C++, Visual Basic that are used to to access database in database management system. Each program contains statements that request the DBMS to perform operation on database. The operations may include retrieving, updating, deleting data etc . The application program may be conventional or online workstations or terminals.

HardwareHardware consists of a set of physical electronic devices such as computers (together with associated I/O devices like disk drives), storage devices, I/O channels, electromechanical devices that make interface between computers and the real world systems etc, and so on. It is impossible to implement the DBMS without the hardware devices, In a network, a powerful computer with high data processing speed and a storage device with large storage capacity is required as database server.

DataData is the most important component of the DBMS. The main purpose of DBMS is to process the data. In DBMS, databases are defined, constructed and then data is stored, updated and retrieved to and from the databases. The database contains both the actual (or operational) data and the metadata (data about data or description about data).

ProceduresProcedures refer to the instructions and rules that help to design the database and to use the DBMS. The users that operate and manage the DBMS require documented procedures on hot use or run the database management system. These may include.

1. Procedure to install the new DBMS.

2. To log on to the DBMS.

3. To use the DBMS or application program.

4. To make backup copies of database.

5. To change the structure of database.

6. To generate the reports of data retrieved from database.

Database Access LanguageThe database access language is used to access the data to and from the database. The users use the database access language to enter new data, change the existing data in database and to retrieve required data from databases. The user write a set of appropriate commands in a database access language and submits these to the DBMS. The DBMS translates the user commands and sends it to a specific part of the DBMS called the Database Jet Engine. The database engine generates a set of results according to the commands submitted by user, converts these into a user readable form called an Inquiry Report and then displays them on the screen. The administrators may also use the database access language to create and maintain the databases.

The most popular database access language is SQL (Structured Query Language). Relational databases are required to have a database query language.

UsersThe users are the people who manage the databases and perform different operations on the databases in the database system.There are three kinds of people who play different roles in database system

1. Application Programmers

2. DatabaseAdministrators

3. End-Users

Application ProgrammersThe people who write application programs in programming languages (such as Visual Basic, Java, or C++) to interact with databases are called Application Programmer.

Database AdministratorsA person who is responsible for managing the overall database management system is called database administrator or simply DBA.

End-UsersThe end-users are the people who interact with database management system to perform different operations on database such as retrieving, updating, inserting, deleting data etc.

DATA MODELIt is a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints.

Each new data model capitalized on the shortcomings of previous models

Common characteristics:

Conceptual simplicity without compromising the semantic completeness of the database

Represent the real world as closely as possible

Representation of real-world transformations (behavior) must be in compliance with consistency and integrity characteristics of any data model

TYPES OF DATA MODELS:

The data model can be divided as follows:

1. Hierarchical model

2. Network model

3. Relational model

4. E-r modeling

5. Semantic models

Object-oriented

Object relational model

1) THE HIERARCHICAL DATA MODEL

The Hierarchical Data Model is a way of organizing a database with multiple one to many relationships. The structure is based on the rule that one parent can have many children but children are allowed only one parent. This structure allows information to be repeated through the parent child relations created by IBM and was implemented mainly in their Information Management System. (IMF), the precursor to the DBMS.

Advantages:The model allows easy addition and deletion of new information. Data at the top of the Hierarchy is very fast to access. It was very easy to work with the model because it worked well with linear type data storage such as tapes. The model relates very well to natural hierarchies such as assembly plants and employee organization in corporations. It relates well to anything that works through a one to many relationship. For example; there is a president with many managers below them, and those managers have many employees below them, but each employee has only one manager.

Disadvantages:This model has many issues that hold it back now that we require more sophisticated relationships. It requires data to be repetitively stored in many different entities. The database can be very slow when searching for information on the lower entities. We no longer use linear data storage mediums such as tapes so that advantage is null. Searching for data requires the DBMS to run through the entire model from top to bottom until the required information is found, making queries very slow. Can only model one to many relationships, many to many relationships are not supported. Clever manipulation of the model is required to make many to may relationships. For example; what if a professor teaches classes, and is also a graduate student? 2) The Network Model

The Network Model replaces the hierarchical tree with graph thus allowing more general connection with the nodes. The more difference between this model to hierarchical model is in case of handling N :N relation . in other words it allows to have more than 1 parent.

Advantages and disadvantages of Network Model:

Conceptual Simplicity: just like hierarchical model it also simple and easy to implement.

Capability to handle more relationship types: the network model can handle one to one1:1 and many to many N: N relationship.

Ease to access data: the data access is easier than the hierarchical model.

Data Integrity: Since it is based on the parent child relationship, there is always a link between the parent segment and the child segment under it.

Data Independence: The network model is better than hierarchical model in case of data independence.

Disadvantages of Network Model:

System Complexity: All the records have to maintain using pointers thus the database structure becomes more complex.

Operational Anomalies: As discussed earlier in network model large number of pointers is required so insertion, deletion and updating more complex.

Absence of structural Independence: there is lack of structural independence because when we change the structure then it becomes compulsory to change the application too.

3) The relational data model:The relational database organizes data in a series of tables. Each table has its own fields specific to the type of data being stored. The database management system (DBMS) designed around the relationships between tables has survived more than two decades because of its flexibility. Once the user enters data into a table and saves it in the massive database, a query will recall the information at any time.ADVANTAGES: Ease of use: The revision of any information as tables consisting of rows and columns is much easier to understand.

Flexibility: Different tables from which information has to be linked and extracted can be easily manipulated by operators such as project and join to give information in the form in which it is desired.

Precision: The usage of relational algebra and relational calculus in the manipulation of the relations between the tables ensures that there is no ambiguity, which may otherwise arise in establishing the linkages in a complicated network type database.

DISADVANTAGES: Performance: A major constraint and therefore disadvantage in the use of relational database system is machine performance. If the number of tables between which relationships to be established are large and the tables themselves effect the performance in responding to the sql queries.

Physical Storage Consumption: With an interactive system, for example an operation like join would depend upon the physical storage also. It is, therefore common in relational databases to tune the databases and in such a case the physical data layout would be chosen so as to give good performance in the most frequently run operations. It therefore would naturally result in the fact that the lays frequently run operations would tend to become even more shared.

Slow extraction of meaning from data: if the data is naturally organized in a hierarchical manner and stored as such, the hierarchical approach may give quick meaning for that data4) THE ENTITY- RELATIONSHIP DATA MODEL:

The Entity-Relationship (ER) model was originally proposed by Peter in 1976 as a way to unify the network and relational database views. Simply stated, the ER model is a conceptual data model that views the real world as entities and relationships. A basic component of the model is the Entity-Relationship diagram, which is used to visually represent data objects. For the database designer, the utility of the ER model is:

It maps well to the relational model. The constructs used in the ER model can easily be transformed into relational tables.

It is simple and easy to understand with a minimum of training. Therefore, the model can be used by the database designer to communicate the design to the end user.