Life cycle of an information system

It is a system, automated or manual, that includes people, machines and / or organized methods to collect, process, transmit data that represent information. An information system encompasses the infrastructure, organization, personnel, and all the components necessary for the collection, processing, storage, transmission, display, dissemination, and organization of information.

Any information system goes through a series of phases throughout its life. Its life cycle comprises a series of stages, among which are the following:

Planning

Carry out a series of preliminary tasks that will decisively influence the successful completion of the project.

Analysis

Find out what exactly the system has to do. The analysis stage in the software life cycle corresponds to the process by which one tries to discover what is really needed and an adequate understanding of the system requirements is reached.

Design

Possible implementation alternatives for the information system to be built must be studied and the general structure of the system (its architectural design) must be decided. The design of a system is complex and the design process must be carried out iteratively.

Implementation

Select the right tools, a development environment that facilitates our work and an appropriate programming language for the type of system we are going to build. The choice of these tools will depend largely on the design decisions we have made so far and on the environment in which our system must operate.

Tests

Its objective is to detect the errors that may have been made in the previous stages of the project (and, eventually, correct them). The error finding carried out at the testing stage can be adapted in different ways, depending on the context and the project phase.

Installation or deployment

We must plan the environment in which the system must operate, both hardware and software: necessary equipment and its physical configuration, interconnection networks between the equipment and access to external systems, operating systems and libraries.

These stages are a reflection of the process followed when solving any type of problem.

Use and maintenance

The maintenance stage typically consumes 40 to 80 percent of the resources of a software development company. In fact, at 60% on average, it is probably the most important stage of the software life cycle.

Eliminate the defects that are detected during their useful life, the first thing that comes to mind when thinking about the maintenance of anything. Adapt it to new needs when the system has to work on a new version of the operating system or in a different hardware environment. Add new functionality when desirable features are proposed that would improve the existing system.

Information systems life cycle

Delimitation of the scope of the project

Determine the aspects covered by the project and how to fix those aspects that will not be included in the project. The latter must be explicitly indicated. If necessary, you can specify everything that is postponed until a later version of the system.

Viability study

With unlimited resources (time and money), almost any project could be successful. Unfortunately, in real life, resources are rather scarce, so not all projects are viable.

Risk analysis

There is always a setback that destroys the best planning. It is something inevitable that we have to live with and for which we have an extremely useful tool: risk management, which is traditionally broken down into risk assessment and risk control.

Classic life cycle

The classic life cycle model, also called the "cascade model," is based on trying to do things right from the beginning, once and for all. One passes, in order, from one stage to the next only after successfully completing the verification and validation tasks specific to the stage. If necessary, only reverse to the immediately preceding phase.

This traditional life cycle model requires a sequential approach to the software development process.

Real projects rarely follow the sequential flow of activities proposed by this model.Normally, it is difficult for the client to explicitly establish all the requirements at the beginning of the project (among other things, because until they see the project evolve they will not have a clear idea of what you really want.) An operational version of the system will not be available until the final stages are reached, so rectifying any decisions made in the initial stages of the project that are wrong will entail a significant additional cost, both financial and temporary.