Systems Development Life Cycle

SDLC, the Systems Development Life Cycle, or Software Development Life Cycle, relates to models or methodologies that people use to develop systems, generally computer systems. Computer systems have become more complex and usually (especially with the advent of Service-Oriented Architecture) link multiple traditional systems often supplied by different software vendors.
To manage this, a number of system development life cycle (SDLC) models have been created: waterfall, fountain, spiral, build and fix, rapid prototyping, incremental, and synchronize and stabilize.

Phases

SDLC adheres to important phases that are essential for developers, such as planning, analysis, design, and implementation, and are explained in the section below. There are several SDLC Models in existence. The oldest model, that was originally regarded as “the SDLC” is the waterfall model: a sequence of stages in which the output of each stage becomes the input for the next. These stages generally follow the same basic steps but many different waterfall methodologies give the steps different names and the number of steps seems to vary between 4 and 7.
There is not a definitive correct model, but the steps can be characterized and divided as follows:

Initiation/Planning

To generate a high-level view of the intended project and determine the goals of the project. The feasibility study is sometimes used to present the project to upper management in an attempt to gain funding. Projects are typically evaluated in three areas of feasibility: economical, operational, and technical. Furthermore, it is also used as a reference to keep the project on track and to evaluate the progress of the MIS team (Post & Anderson, 2006)

Requirements Analysis

The goal of systems analysis is to find out where the problem is in attempt to fix the system. This step involves breaking down the system in different pieces and drawing diagrams to analyze the situation. Analyses project goals, breaking down functions that need to be created, and attempts to engage users so that definite requirements can be defined.

Design

Functions and operations are described need to be detailed, including screen layouts, business rules, process diagrams and other documentation. The output of this stage will be to describe the new system as a collection of modules or subsystems.

Build

Modular and subsystem programming code will be accomplished during this stage. This stage is intermingled with the next in that individual modules will need testing before integration to the main project.

Testing

The code is tested at various levels. Unit, system and user acceptance testing are often performed. This is a very grey area as many different opinions exist as to what the stages of testing are and how much if any iteration occurs. Iteration is not generally part of the Waterfall model, but usually some occurs at this stage.

Types of testing:

• Data set testing
• Unit testing
• System Testing
• Integration testing
• User acceptance

Implementation

The final stage of a project or the initial development, where the software is put into production and is used by the actual business.

Types of implementation:

• Documentation
• Training
• Parallel implementation
• Big-bang implementation (Direct cutover, Plunge)
• Phased implementation
• Pilot implementation

Operations and Maintenance

The life of the system which includes changes and enhancements before the decommissioning or sunset of the system. Maintaining the system is a very important aspect of SDLC. As key personnel change position in the organization, new changes will be implemented, which will require system updates.