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Data Processing Notes

System Development Cycle

INTRODUCTION

Information systems are important for the success of any modern business for organization. Every many information systems are being developed to make them more competitive and improve the productivity and profit.

The two keys required for a successful development of information system are:

  • Thorough Systems analysis and design
  • Understand what the Business or organization requires.

Definition of terms

Systems analysis is the process of understanding in detail what a system should accomplish, how it will accomplish it required to accomplish it.

Systems design is the process of specifying in detail how components of an information system should be implemented physically.

Systems analyst is a person that uses analysis and design techniques to solve business problems using information technology.

Skills of a systems analyst

To be a good and successful systems analyst, the person must have the following skills:

  • Information technology knowledge and programming expertise.
  • Understand business problems.
  • Use logical methods for solving problems.
  • Ability to find facts about the problem and develop how it should be solved.
  • Always wanting the improvement of the system.
  • People management knowledge and skills.

Systems Analyst Problem solving Approach

The steps taken by a system analyst to solve problems are stated below:

  1. Study and understand the problem: The analyst must identify that there is a problem to be solved and specify that it is feasible to solve the problem.
  2. Define the requirements for solving the problem: The analyst will identify the facts or data that are required to solve the problem.
  3. Develop a set of possible or alternative solutions: If there are alternative solutions, the systems analyst must develop them and decide on the best solution to use. However, in most cases, there may be only one solution which is chosen.
  4. Define the details of the chosen solution: All the facts and method need to solve the problem are specified in detail.
  5. Solve the problem: The problem is solved using the chosen solution method.
  6. Monitor to ensure that desired result or outcome is accomplished: Here, the analyst will make sure that the formula is not miscalculated.

Example: let us apply this process in solving a simple interest (SI) problem: A man invested the sum of N500, 000.00 for 5 years at an interest rate of 12% per annum. Calculate the amount at the end of the period.

Solution:

Step1: Study and understand the problem: the simple interest is understood as defined.

Step 2: verify that the benefits of solving the problem outweigh the cost: The SI can be solved with our current knowledge and the resources that we have like four figure tables, calculator and so on. We do not need to hire anybody.

Step3: Define the requirements for solving the problem: the requirements for solving the SI problem are Principal (N500, 000.00), rate (12%) and Time (5years).

Step4: Develop a set of possible or alternative solutions: The problem can be solved in two ways: First calculating the SI using the formula (I=P*R*T/100) and then calculate the amount as A=Principal + Interest. Secondly, another way is calculating the Amount using the formula that A=P (1+(R*T/100))

Note that *means multiplication.

Step 5: Decide which solution is best and recommended: We decide to use the first method because it is simpler than the second.

Step 6: Define the details of the chosen solution: The variables (facts) that we need to solve this problem are as stated in step 3 above and the procedure are as stated on step 4(1) above.

Step 7: Implement the solution: The problem is solved as follow:

  1. I=P*R*T/100

= 500,000*12*5/100= N300, 000.00

ii.         Amount= P+I= N500, 000+ 300,000 =800,000

Step 8: Monitor to ensure that desired result is accomplished. To make sure that the formula procedure and calculations are correct.

CONCEPT OF SYSTEMS

What is a system?

A system is a collection of interrelated components that function together to form a whole and achieved outcome. Examples:

What is an information system?

An information system is a collection of interrelated components that collect, process, store and provide as an output the information needed to complete a (business) task.

In systems development, application systems are referred to as information systems. Therefore, an information System can also be defined as a collection of programs running on computers which interact with one another as well as humans to provide the necessary information needed to make decisions within an organization.

What is a subsystem?

A subsystem is a part of a larger system that can function on its own to perform a task. It can be a system having subsystems or it may just be a single system. The components that make up the overall computer system can be described as sub-systems. These are mainly hardware and software subsystems. The process of dividing a system into subsystems and components is called Functional Decomposition.

Information systems and subsystems

A school information system will have the following subsystems: Academic system, Examination Systems, Discipline system, Hostel/Accommodation system, Library system, Fees Billing System, Staff System, Bursary System and so on.

Information Systems and Component Parts

The main components of information systems are:

  1. IT i.e. hardware and software
  2. Data/information
  3. Procedures/policies
  4. People
  5. Communication Networks

Types of Information Systems

The ‘classical ‘types of Information Systems found organizations are:

  1. Transaction processing systems
  2. Management information systems
  3. Decision support systems
  4. Executive information systems

Some new types of information systems that cannot be classified as above are listed below:

  1. Data warehouses
  2. Enterprise resource planning
  3. Enterprise systems
  4. Expert systems
  5. Geographic information system
  6. Global information system
  7. Office Automation

Systems Development Life Cycle (SDLC)

Systems development is a planned undertaking with a fixed beginning and end that produces the desired result or product. It may be a large job that involves many people working for a long period or it can also be a small assignment that one person can finish in a day. The SDLC PROVIDES AN OVERALL FORMALISED METHOD FOR managing the systems development processes and activities. It represents a detailed and specific set of procedures, steps, and documents that are required for the development of an information system development.

The SDLC believes that the development of information systems should follow a structured and methodical way, requiring each stage of the life cycle from inception of the idea to delivery of the final system, to be carried out in rigid and sequential order.

Definition of SDLC: The systems development life cycle is the process of understanding how an information system (IS) can support the business needs of an organization, designing the system, building it and delivering it to the users.

Objectives of SDLC

The objectives of SDLC are:

  1. To ensure high quality systems are delivered.
  2. To provide strong controls over the system development
  3. To maximize the productivity of the systems staff

STAGES IN SYSTEMS DEVELOPMENT LIFE CYCLE

However, there are methods for developing information systems. The oldest and classical method of systems development life cycle (SDLC) is called the Waterfall Model. The waterfall SDLC is a sequence of stages that must be followed one after the other. Stage 2(two)  can only begin when stage one is completed. Therefore the output of each stage becomes the input for the next. These stages can be characterized and divided up in different ways, including the following:

  1. Investigation stage
  2. Systems Analysis stage
  3. Systems Design Stage
  4. Systems Implementation stage
  5. Systems Deployment
  6. Systems maintenance Stage
  1. Investigation stage: this stage involves the investigation of the existing system. The existing system is studied and evaluated to identify its problems and deficiencies. It involves gathering information about the existing systems. The information could be gathered through Observation(observing the system), Questionnaire(preparing questionnaires based on the existing system and give to the users to fill) and Interviewing(asking the users verbal questions about the system). The information gathered is used in a feasibility study. The aim of the feasibility study is to identify the problems and proffer feasible solution through a feasibility report. It also identifies how this problem is to be solved(either manually or computerized), when it is to be solved and why it should be solved. It defines the objectives and goals that the new system to be developed will achieve. The feasibility report is the main output of the investigation.
  • Systems Analysis stage: This stage starts with a more detailed investigation into the existing system. The same facts finding methods of observation, questionnaire and interview are used to gather end-users information such as data and procedures and processes. The data and procedures are analyzed to define the new system requirements. The new system requirements are defined addressing the deficiency in the existing system with specific proposals for improvement. The output of the analysis stage is the users’ requirements.
  • Systems Design Stage: At this stage the proposed system is designed. It involves layout plans for the physical construction, hardware requirements, operating systems, programming, communication, and security. The design describes the desired features and operations of the proposed system in detail, including screen layouts, business rules, process diagrams, flow charts, pseudo-code and other documentation such as data dictionary and so on. The system design stage produces the Systems Specification.
  • Systems Implementation stage: This stage is the stage where programs of the new system are written in the specified programming language in line with the systems specifications. It involves testing of all the new system and adjustments and corrections are made where necessary.
  • Systems Deployment: Here the system that was developed in stage 4(four) is put into use. It involves bringing all the different parts the proposed system together. All parts of the system is integrated and tested for errors, bugs and how they operate. It includes the installation and deployment. This is the stage where the software is put into use and runs the actual business.
  • Systems maintenance Stage: once the new system is deployed and running, it is subjected to exhaustive evaluation on how it is able to achieve its setup goals. Areas for improvement will be modified and enhanced. Sometimes the mistakes or errors can be detected. Procedures and processes may change. Thus the remaining life of the system is subject to changes, correction, additions, moves to a different computing platform and more. The system maintenance stage involves all the activities, processes and procedures required by the system to exist forever.
  •  

ADVANTAGES OF SDLC

  1. Simple and easy to use
  2. Easy to manage due to the rigidity of the model.
  3. Phases are processed and completed one at a time works well for the development of smaller information systems where requirements are very well understood.
  4. Provides guidelines for systems development as all the stages and activities are clearly outlined
  5. Promotes consistency among systems development projects.
  6. Reduces cost of managing different systems at different stages.
  7. Helps in efficient allocation of resources to systems development projects.

DISADVANTAGES OF SDLC

  1. Adjusting scope during the life cycle can kill a project.
  2. No working software is produces until during the life cycle
  3. High amounts of risk and uncertainty.
  4. Poor model for complex and object-oriented projects.
  5. Poor model for long and ongoing projects
  6. Poor model where requirements are at a moderate to high risk of changing.
  7. If followed slavishly. It can result in the generation of unnecessary documents.
  8. It takes time to go through the whole long development cycle.

Reading Assignment: Reading Assignment:

Hiit @ School, Computer Studies for Senior Secondary Education. Pgs 104 -105

WEEKEND ASSIGNMENT

OBJECTIVE

  1. One of the following is NOT an objective of SDLC
  1. To minimize the productivity of the system staff
  2. To ensure that high quality system is delivered
  3. To maximize the productivity of the system staff
  4. To provide strong control over the system development
  5. ___________is the person that uses analysis and design techniques to solve business problem using information technology.
  6. Programmer     b. Data Entry Staff     c. System Analyst       d. Computer Engineer
  7. The following are skills of a system Analyst EXCEPT one
  1. Information Technology knowledge and programming expertise
  2. Solving the problem using figures
  3. People Management knowledge and skill
  4. Understanding business problem
  5. ___________is the process of understanding in details what a system should accomplish it and what is required to accomplish it.
  6. System Design            b. System Analyst       c. System Analysis      d. SDLC
  7. The following are advantages of System Development Life Cycle EXCEPT one
  1. Help in inefficient allocation of resources to systems development project
  2. Promotes consistency among systems development project
  3. Simple and easy  to use
  4. Easy to manage due to the rigidity of the model

THEORY

  1. Define the system development cycle.
  1. List five stages in system development cycle
  2. Explain at least five (5) systems Analyst problem solving Approach
  3. Describe the first stage in system development cycle
  1. Draw a simple sketch of system development cycle.
  2. State the objectives of SDLC

EVALUATION

  1. Define the System Development Cycle
  2. List the stages in SDLC

Reading Assignment: Reading Assignment:

Hiit @ School, Computer Studies for Senior Secondary Education. Pgs 101 – 103.

WEEK FIVE (5) WEEKEND ASSIGNMENT

OBJECTIVE

  1. _______ is a collection of interrelated components that function together to form a whole and achieve an outcome.
  2. Subsystem       b. System        c. Life cycle    d. Development
  3. The following are the Water fall Development cycle stage EXCEPT______
  4. Investigation Stage     b. System analysis Stage        c. System manufacturing Stage
  5. System design Stage
  6. The oldest and classical method of SDLC is called_________   a. Waterfall Mean      

b. Waterfall Model           c. Waterfall Median    d. Waterfall Mode

4.  One of the following is NOT an information system component part.     a. People        

b. Communication Network   c. IT room       d. Data/ Information

5.  The following are classical types of information system EXCEPT one.

a. Transaction Processing System           b. Development Processing System

c. Management information System       d. Executive information system

THEORY

  1. Define the following;    I. System Development Life Cycle        II. System Analysis

III. System Design       IV. System Analyst

  1. Explain the following;    I. System         II. Information System III. Subsystem

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