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Monday, April 15, 2013

Computer Aided Software Engineering (CASE) | HSEB Notes of Computer Science Class 12

Chapter : One
Computer Aided Software Engineering (CASE)
Subject : Computer Science
Class : 12

CASE stands for Computer- Aided Software Engineering. Case is the technology for automating software development and maintenance. Project teams (members who develop information system) use special software applications for creating prototypes quickly, building diagrams, writing codes and managing development. These applications are called CASE tools. Thus CASE tools are the types of software that automates the development of information system.

Prototypes:
Prototypes are the experimental version of new software (or information system). Prototypes are designed to show the structure and design projected for the final product. Prototyping is used in the development of both new hardware and software systems and new system of information management. A typical Prototype consists of screens with few items like: buttons, field and options. Each item in the Prototype has minimal functions. By experimenting with a prototype, users become familiar with the end product long before it is actually developed. Prototyping is an important component of Rapid Application Development (RAD). CASE Tools are used to design Prototypes. 

System Documentations: 
System manual contain the detail technical information for each application system. It describes each of the major functions performed by the application, the data affected by the application and logical flow of data within the system. These manuals usually include: 
  • Narrative describing the purpose of the application.
  • Description of the files, database and records within application
  • Display format and uses
  • Possible sample report of the program
The various ways of documenting are:
  • Presenting in the flowchart
  • Using pseudo code
  • Using the structured English and algorithms 
System Analyst: 
The systems Analysis is the process if totally understanding the current system by collecting the facts, diagnosing the problems and using the facts to improve the current system. Systems Analysis is done by the System Analyst. A system analyst is the person who is responsible for the analysis, design and implementation of the business system to the computer. A system analyst can be described as the person who will solve the business problem using computer technology so we need someone who is good at the problem solving who knows about business operation and who has a strong background in relevant areas of computer science. 

Qualities (Skills/Knowledge) of system Analysts: 
Expertise in system analysis and design comes with experience and time. However, there are some essential qualities that Systems Analysts should posses, they are: 

1. Communication Skills: 
The analysts must be a good communicator. The analyst is the medium through which communication should flow smoothly. He or she must be able to gain information requirements from users and to communicate well with programmers. 

2. Problem Solving Skills: 
Systems are developed to solve problem. The analyst is a problem solver. He or she views the analysis of problem as a challenge. An analyst must have wide experience in solving the problems. The steps of solving problems are: 

1. Define the problem
2. Analyze problem
3. Consider alternatives for removing the cause
4. Evaluate these alternatives and try to know their benefits and disadvantages
5. Choose the best alternatives.
3. Technical Knowledge

The analyst needs enough computer experience to program and understand the capabilities of the computers. Analyst must be familiar with the capabilities and administration of hardware and software products. 

4. Business Knowledge: 
The analyst should be capable of handling the situation through skillful application of tools and techniques. It is important for an analyst to completely understand the business environment for which the system is being developed. They must be familiar with existing business operations so that they can decide if a computer can do the better job. 

Duties and Responsibilities of System Analysts: 
The duty of the system analyst is to co-ordinate the efforts of all groups to effectively develop and operate computer based information systems. The major duties and responsibilities of a system analyst are as follows: 

a. Defining User’s Requirements: 
This particular duty is the most difficult and analyst will have to use several fact-finding techniques like interview, questionnaire, observation and automation. 

b. Prioritizing requirements by agreement: 
By conducting common meeting and arriving at a agreement or consensus, analyst can prioritize the requirements. 

c. Analysis and Evaluation: 
On the basis of facts and opinions, system analyst finds the best characteristics of the new or modified system which will meet the user’s stated information needs. 

d. Solving Problems: 
System analyst is basically a problem solver. He must study the problem in depth and suggest alternate solutions to management. 

e. Drawing up functional specifications: 
The main duty of the analyst is to obtain the functional specifications of the system to be designed and specification must be non-technical so that users and managers can understand. 

f. Designing System: 
One of the major duties of the analyst is to design the system and it must be understandable to the system implementer. 

g. Evaluating System: 
It is analyst critical duty to evaluate a system after it has been in operation for certain period of time. 

Role of a System Analyst: 
Success of every development depends on the role of system analyst. The major roles of system analyst are: 
  1. Plan and develop new system or device ways to apply existing system resources to additional operations.
  2. Keep constant track of the system and constant interaction with management, middle level manager and working level personnel to achieve the logical and accurate perspective of the system.
  3. Use techniques like structured analysis, data modeling, information engineering, mathematical model building, sampling and cost accounting to plan the system.
  4. Specify the inputs to be accessed by the system design the processing steps and format the output to meet the users need.
  5. Prepare the cost benefit and return on investment analysis to help the management decide whether implementing the propose system will be financially feasible.
  6. Co-ordinates tests and observes initial use of the system to ensure that it performs as planned.
  7. Prepare specification, work diagrams and structure charts for computer programmers to follow and then work with them to ‘debug’ or eliminate errors from the system.
  8. Diagnose problems, recommend solutions and determine if the program requirements have been met. 
Feasibility Study: 
Feasibility study is carried by System Analysts. The feasibility study or analysis carefully examines technical, economic, operational, scheduling, legal and strategic factors of a system to make sure that the system can be successfully developed. There major areas are considered while determining the feasibility of a project. They are: 

a. Technical Feasibility Study: 
This study is done by System Analysts to find out whether current technical resources which are available in the organization are capable of handling the user’s requirements. If not, then the analysis confirms whether the technology is available in the market. 

b. Economic Feasibility Study: 
This study evaluates the financial aspects of the project by performing a cost benefit analysis and addressing both tangible (real) or intangible benefits of the system. Economic or Financial Feasibility considers the following points:
  • Cost of doing full system study
  • Estimated cost of hardware
  • Estimated cost of software tools and systems development
The concerned organization must be able to evaluate the investment before implementing the entire system. If the system is not economically feasible, the project should not be proceed further. 

c. Operational Feasibility Study: 
Once it is determined that the system is both technically and economically feasible then it has to be concluded if it is operationally feasible. It determines whether there will be any problem in implementing the system in its operational environments, looks at issues such as integrating the new system with existing systems in the organization, and assess how the system fits with the strategic business plan and strategic information plan of the organization. 

d. Schedule Feasibility Study: 
It address the time it will take to complete the project, taking into consideration available resources and additional resources required, if any. 

e. Legal Feasibility Study: 
This study takes into account factors such as copyrights, patents and government regulations. 

f. Strategic Feasible Study: 
This study looks into factors such as the ability of the system to increase market share, give the firm a competitive advantages in the market place, enhance the productivity of knowledge workers and achieve other strategic goals of the organization. 

Aims of Feasibility Study 
The aims of feasibility study are:
  • Defining the major problems areas, so that the system analyst can plan the strategy for the field investigation.
  • Discovering the areas where some specialist knowledge is required for the full investigation.
  • Determining whether the objectives stated in the assignment brief are reasonably attainable within the limitations and financial constraints period.
  • Determining the approximate time required for the full investigation and there cost.
System Security: 
In a common sense, security is freedom from any risk or danger. In context of computer science, security is prevention of or protection against:
  • Access to information by unauthorized people
  • Unauthorized destruction or alteration of that information
In other words, a secure system is a system on which enough trust can be put to use it together with sensitive information. Computer Security is frequently associated with three cores of areas;

a. Confidentiality: Ensuring that the data cannot be accessed by unauthorized persons.
b. Integrity: Ensuring that information is not altered by unauthorized person in a way that is not detectable by authorized persons.
c. Authentication: Ensuring the users are the person they claim to be. 

Computer Security is also defined as: 
a. Physical Security: Controlling the coming and outgoing of people and materials, protection against the elements and manual disasters.
b. System Security: User access and authentication controls, maintaining file and file system integrity, make backups, log keeping and auditing.
c. Personal Security: Hiring employee to background screening, monitoring and handling departure of persons.
d. Network Security: Protecting network and telecommunication equipment, controlling access from un-trusted.

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