Instructor: Louay Chebib
The software development life cycle (SDLC) and software testing life cycle (STLC) work in conjunction with each other as part of effective software development. Read on to learn more.


Ever ask yourself how is it possible to manage very large software projects? Just like building a skyscraper, a bridge, a house or even renovating your kitchen, a software project can quickly be delayed or go over budget by mismanagement, lack of control, by misdirected resources or activity. Project managers depend on standardized tools and techniques to help make sure everything is proceeding, as it should.


Originally, software project managers relied on the traditional tools used in designing and building large engineering projects such as skyscrapers, roads and bridges. The complicated demands of software development led to a better understanding of managing complex projects by breaking down the work into small easily managed parts.

These methods rely and on a cyclical model where each development cycle includes the following components: identify the need, evaluate the available options, develop the component, verify what was built, and plan for the next time around, and starts and ends with something that works. These newer models and techniques are now being applied to all types of projects. The design-build method now used in engineering projects is based on the cyclical model. Can you think of a construction project that used this model?

Cyclical Development Process

Cyclical Development Model
Spiral Model

A cyclical development process allows for greater flexibility in managing any project. By splitting projects into modular tasks and using a cyclical process, it is no longer necessary to wait for all previous steps to be complete before starting on a task. The cyclical processes used in software development support developing each module independently. As a bonus, once a module is ready, it can be used over and over whenever and wherever it's needed.

Think of how many apps your smartphone has. Each of these can be used on its own, but the best ones rely on one another. Your phone app needs a phonebook; your messaging app needs a phonebook, your email app needs a phonebook, and so on. Instead of having a separate phonebook for each, your smartphone relies on a single contacts app that is shared by many other apps. The designer of each of the separate apps only needs to know how to talk to the contacts app.

i.e. Once the overall design is ready and the interface of the module is defined, work can start on that module even if the detailed design of every component module is not yet ready.

Project Management

Project managers rely on a variety of tools that help them create a project roadmap in terms of its goals, its scope, its design, and its resource needs. The software development life cycle (SDLC) provides a template for this roadmap. The SDLC steps or phases consist of:

  1. Gathering requirements
  2. Designing the system
  3. Developing the system
  4. Testing the system
  5. Deploying the system
  6. Maintaining the system

A software testing life cycle (STLC) accompanies each step of the software development life cycle (SDLC). Testing at every stage of software development helps make sure that the software will do what is expected, but also makes sure that nothing is missed and that the expectations match what clients need and what they are looking for.

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