Difference Between SDLC and Waterfall Model

Difference Between SDLC and Waterfall Model: If you are developing software and the project is going to be big, then you would be doing something wrong if you did not have a good development lifecycle in place. If your software is mission-critical or has some serious security requirements, then even more so.

Having said that it’s obvious that you do need quality management processes in place before you start development. Some of these processes can be largely automated, whereas some are more best practice/common sense based.

Waterfall Model

The waterfall model is a sequential methodology that treats the product development process as a series of time-boxed phases of activities, each phase being completed before the next phase can begin.  It is also called an “accumulative” approach as it moves from one phase to another in a stepwise manner, accumulating knowledge through each phase before passing this knowledge to the next phase.

This model is also called sequential integration because it proceeds in a sequence from one development step to another, eventually leading to a fully developed product or service.  The waterfall model involves multiple phases of project management, focusing on deliverables instead of outcomes and emphasizing a detailed plan for completing defined work products before moving to the next stage.

It is intended to lead deliverables through a series of well-defined steps, from inception through deployment.  In the waterfall model, the conception of phase and project lifetime becomes very important as it allows you to define what should be done at which time.

The five steps in the Waterfall model are as follows:

  • Inception:  is where the project requirements are identified, documented, and approved.  The purpose of this step is to make sure all desired product features are clearly defined before moving on to the next stage.
  • Elaboration:    in this step, design specifications are created and prototypes may be built.
  • Construction:      in this step, the product is built according to design specifications and architectural standards.
  • Verification & Validation:    in this stage, the software is tested for compliance with the project plan through a series of “acceptance tests” against specific criteria (called ‘test cases’ or ‘exit criteria’).
  • Deployment:  in this stage, the product is released to the end-user and maintained.

Software Development Life Cycle Model (SDLC):

Software Development Life Cycle (SDLC) is a process that includes the methods, tools, and procedures used to develop and sustain software products.  It has different stages of development starting from the concept stage all the way up to production deployment and monitoring.

Most SDLC models include five stages: requirements analysis, design, coding, testing, and implementation:

  • Requirements analysis:  In this step, the needs and expectations of the users are analyzed to determine an appropriate design for the software.
  • Design:  Design is a process of planning how a system should work, taking into consideration its intended use, the available resources, and constraints imposed by other systems (e.g., legacy systems).
  • Coding:    In this step, the code is written according to design specifications.
  • Testing:    After coding is completed, the software goes through a test phase in which various aspects of the software are tested to determine if they meet design and implementation guidelines.
  • Implementation:  After testing has been completed and all problems have been corrected, it is time to transfer the software to the intended users.

Difference Between SDLC and Waterfall Model

We are going to share some of the key differences between the SDLC vs Waterfall model.

Agile Waterfall
Iterative development in short sprintsThe sequential development process in pre-defined phases
Flexible and adaptive methodologyThe process is documented and follows the fixed structure and requirements agreed upon at the beginning of the process
Feedback-based approach: Sprints lead to short build updates that are evaluated on and guide the future direction of the development
Limited and delayed feedback: The software quality and requirements fulfillment isn’t evaluated until the final phase of the development processes when testers and customer feedback is requested.
A provision for adaptability: Project development requirements and scope is expected to change over the course of the iterative development process.The requirements and scope are definitive once agreed upon.
The SDLC phases overlap and begin early in the SDLC: planning, requirements, designing, developing, testing, and maintenance.The SDLC phases are followed in order, with no overlap. Members of one functional group are not involved in another phase that doesn’t belong to their job responsibilities.
Follows a mindset of collaboration and communication. The requirements, challenges, progress, and changes are discussed between all stakeholders on a continuous basis.Follows a project-focused mindset with the aim of fully completing the SDLC process.
Responsibilities and hierarchical structure can be interchangeable between team members.Fixed individual responsibilities, particularly in management positions.
All team members focused on end-to-end completion (achieved sequentially) for the projects.Team members focused on their responsibilities only during their respective SDLC phases.
Suitable for short projects in high-risk situations.Suitable for straightforward projects in predictable circumstances.
Limited dependencies as the focus are less on implementation specifics, and more toward the mindset.Strict dependencies in technologies, processes, projects, and people.

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