The Information System life cycle

The Information System life cycle

The purposes of the information system life cycle:

- The information system life cycle provides an conceptual framework for presenting and understanding the activities involved throughout the system development process.

- The system life cycle also provides a management framework for scheduling and coordinating information system development and for monitoring its process.

It is based on the use of structured methods of analysis, design and programming

- There are 8 phases in the system life cycle:

n Identify user needs

n Establish user requirement

n Determine the hardware and system software environment

n Design the system

n Develop th

n e system acceptance tests

n Construct the system

n Integrate the system with the using organization

n Operate, modify, and enhance the system.

Identify the users needs: determine the proposed system promises sufficient potential benefit to invest the additional resources necessart to establish the user requirements in greater detail

Establish user requirements: involves analyzing how things are currently being done and then describing the new system explicitly and in detail. Structured specification, a document containing the new system requirements and defining what parts of it are to be automated. – more realistic estimates of the cost and effort to compete the system design and development.

Determine the H/W and S/W: OS, DB, I/O, creating the supporting CG displays and UI; H/W selection and configurations from several vendors

Design the system: requirements presented in the structured specification are also the basis for system design.

Completed system design is also used to prepare plans, budgets and schedules for programming, testing, and debugging te system

Develop the system acceptance

- performance targets established in the structurd specification are used to develop detailed and specific tests of acceptable system performance

- tests determine whether the system as constructed by its developers satifies the users’ requirements

- the acceptance tests should e developed by people who are not involved in the design or construction of the system.

Construct the system: review, use and evaluation of the user manual is part of the acceptance test.

Integrate the system with the using organization: this requires the training of the users, the delivery and installation of any additional hardware, the conversion or creation of the files or database for the system plus, possible of the parallel operation of both old and new systems.

After the transition & integration is over, the post-implementation review should be held to evaluate whether the orginal system objectives as wel as the user’s requirements and performance targets continue to be met.

Operate, modify and enhance the system.

- if the post-implementation review find a discrepancy between the system’s performance and the specified system requirements, it will be necessary to correct the deficiencies (or relax the performance requirements)