SYSTEM LIFE CYCLE
The system life cycle is the name given to a various tasks which have to be carried out when a
new information technology system is being created.
The System Life Cycle could be organised as follows:
1. Detailed Problem Definition
2. Feasibility study
3. Analysis
4. System Design
5. Programming
6. Testing
7. Implementation
8. Maintenance.
THE STAGES OF SYSTEMS ANALYSIS
PROBLEM DEFINITION
This should give a clear picture of what the physical system is. First a survey of the system is
done which helps in identifying the scope of the system. There must be an in-depth study of
identification of user’s requirements, and the limitations and problems of the present system. It’s
important to define precisely what is required. The opinion of the people working in the
organisation should be considered.
FEASIBILITY STUDY
Feasibility study is the decision of whether to convert a manual system into a system using
information technology. An investigation of a problem is carried out to decide if a solution is
possible and how it may be done. It helps businesses decide if converting from a manual to an
information technology method is going to be successful and worthwhile. So, a feasibility study
gives a company the opportunity to either stop the systems design process and stay with the
manual method or continue developing a new information technology system and say what things
they would like to be automated using IT
SYSTEMS ANALYSIS
Analysis involves a detailed study of the current system to find out what features the current
system has and what additional features should be included. This will lead to specifications of a
new system. The analyst will usually:
Research how the previous system worked through the use of interviews, on-site observation
(observes the manual system and looks at how it works) existing documentation,
questionnaires (eg: asks users of the current system for their opinion of it and how it can be
improved) and experience. Sometimes this may be formally documented to provide a basis for
the new system.
Identify the main requirements for the system (requirements specification)
Identify what is input to the system and output from the system
Identify the likely hardware and software constraints
SYSTEM DESIGN
A detailed description showing how the new system will be constructed is produced. Design can
include:
a drawing of the System flowchart to show the flow of information
description of the input and output formats and contents
produce a specification for each program in the system
list general routines and standards for use within the system
establish the security and recovery procedures
PROGRAMMING
The programmer converts the program specifications into computer instructions, which we refer as programs.
TESTING
Testing makes sure the system works as described in the specification and a test run of the
system is done removing all the bugs, if any. A test plan should be developed and run on a given
set of test data. The output of the test run should match the expected results.
Testing is to ensure that:
the programs work together correctly
invalid data is trapped
security and recovery techniques are safe
TRAINING
It’s useless to have a good system if the users don’t know how to use it. The users have to be
trained to use the new system. Usually, personal explanation is far better than studying a user’s
manual because the user can ask questions when in doubt.
DOCUMENTATION
Documentation is the written information and diagrams which enable the development of the
system. The documentation usually consists of technical documentation, user documentation and
if necessary installation instructions. It includes technical documentation, maintenance
documentation, systems documentation, program documentation. (refer to Documentation notes)
IMPLEMENTATION
Implementation is the process of starting to use an information system in a real situation after
having designed and developed it. It may include final testing. Different approaches are used
depending on the size of the system and the properties of the data being processed. There are
four major methods of implementing a system direct, parallel, staggered and pilot-run.
MAINTENANCE
Maintenance is necessary to eliminate errors in the system during its working life and to tune the
system to any variations in its working environment. So, maintenance is important to ensure that
the system continues to run smoothly to meet changed requirements
The system life cycle is the name given to a various tasks which have to be carried out when a
new information technology system is being created.
The System Life Cycle could be organised as follows:
1. Detailed Problem Definition
2. Feasibility study
3. Analysis
4. System Design
5. Programming
6. Testing
7. Implementation
8. Maintenance.
THE STAGES OF SYSTEMS ANALYSIS
PROBLEM DEFINITION
This should give a clear picture of what the physical system is. First a survey of the system is
done which helps in identifying the scope of the system. There must be an in-depth study of
identification of user’s requirements, and the limitations and problems of the present system. It’s
important to define precisely what is required. The opinion of the people working in the
organisation should be considered.
FEASIBILITY STUDY
Feasibility study is the decision of whether to convert a manual system into a system using
information technology. An investigation of a problem is carried out to decide if a solution is
possible and how it may be done. It helps businesses decide if converting from a manual to an
information technology method is going to be successful and worthwhile. So, a feasibility study
gives a company the opportunity to either stop the systems design process and stay with the
manual method or continue developing a new information technology system and say what things
they would like to be automated using IT
SYSTEMS ANALYSIS
Analysis involves a detailed study of the current system to find out what features the current
system has and what additional features should be included. This will lead to specifications of a
new system. The analyst will usually:
Research how the previous system worked through the use of interviews, on-site observation
(observes the manual system and looks at how it works) existing documentation,
questionnaires (eg: asks users of the current system for their opinion of it and how it can be
improved) and experience. Sometimes this may be formally documented to provide a basis for
the new system.
Identify the main requirements for the system (requirements specification)
Identify what is input to the system and output from the system
Identify the likely hardware and software constraints
SYSTEM DESIGN
A detailed description showing how the new system will be constructed is produced. Design can
include:
a drawing of the System flowchart to show the flow of information
description of the input and output formats and contents
produce a specification for each program in the system
list general routines and standards for use within the system
establish the security and recovery procedures
PROGRAMMING
The programmer converts the program specifications into computer instructions, which we refer as programs.
TESTING
Testing makes sure the system works as described in the specification and a test run of the
system is done removing all the bugs, if any. A test plan should be developed and run on a given
set of test data. The output of the test run should match the expected results.
Testing is to ensure that:
the programs work together correctly
invalid data is trapped
security and recovery techniques are safe
TRAINING
It’s useless to have a good system if the users don’t know how to use it. The users have to be
trained to use the new system. Usually, personal explanation is far better than studying a user’s
manual because the user can ask questions when in doubt.
DOCUMENTATION
Documentation is the written information and diagrams which enable the development of the
system. The documentation usually consists of technical documentation, user documentation and
if necessary installation instructions. It includes technical documentation, maintenance
documentation, systems documentation, program documentation. (refer to Documentation notes)
IMPLEMENTATION
Implementation is the process of starting to use an information system in a real situation after
having designed and developed it. It may include final testing. Different approaches are used
depending on the size of the system and the properties of the data being processed. There are
four major methods of implementing a system direct, parallel, staggered and pilot-run.
MAINTENANCE
Maintenance is necessary to eliminate errors in the system during its working life and to tune the
system to any variations in its working environment. So, maintenance is important to ensure that
the system continues to run smoothly to meet changed requirements