A systems development life cycle is the method of organizing the creation, use and disposal of new hardware and software in the computer industry. A systems development life cycle follows the same pattern as most new inventions: find a problem, design the solution and then implement the solution. The term is a catchall for a large number of different methodologies and processes, all of which follow this same basic pattern.
There isn’t a single process called a systems development life cycle--rather, there are many different methodologies and models that all fall under the term. The most basic model, often called the Waterfall Method, consists of seven steps. These steps are taken in a specified order, each building on the last. While this makes the Waterfall one of the most complete models, it also makes it the slowest and most expensive.
Other developmental methods work on similar, but different, principles. Other systems development life cycle methods skip, combine or reorder the basic steps. Generally, this is done to speed up the creative process or lower developmental costs. In addition, models exist to take advantage of alternate computing styles and business structures.
The basic steps of a systems development life cycle are broken into four areas. The first three, design, construction and implementation, are common parts of many new systems and inventions. The forth, disposal, is relatively uncommon. Most of these four areas have ‘substeps’ that make up the full cycle.
Design is the first step in nearly every model, because without an idea there isn’t anything to build. The design step has the largest number of substeps of any of the areas. Initiation requires that a project be brought to the design team to begin the process. The systems concept and planning steps center on internal accounting and feasibility studies for the designing company. Requirements analysis centers on focusing on user needs, and design is the initial creation of the software or hardware model.
The construction phase in a software development life cycle is often one of the longest. During these substages, the hardware or software is actually built and tested. The first step, development, is the actual creation of the system, and depending on the project, this can take anywhere from days to years to complete. The second step, testing, involves non-developers using the product in order to generate feedback. Based on that feedback, the project will return to development or go onto the next phase.
Implementation is when users are actually using the software or hardware. During the first substep, also called implementation, the project is integrated into existing systems, and user training takes place. Operations and maintenance comprise the second step. During this time, its target audience uses the project normally and performs regular maintenance on the system.
The last area, disposal, has no substeps. During this phase, the project is pulled out of the users' systems. If it is hardware, it is disposed of normally. Software is migrated out, and existing data is converted to a newer system that is entering its implementation phase.