SDLC Methodologies

8 min readNov 20, 2020


Hi every one 👋👋 ,today I would like to write this article about SDLC Methodologies.This article mainly include following contents introduction of the Software development lifecycle methodologies and Discuss about each methods with their advantages and Disadvantages.

To start with, what is SDLC? Here’s a simple software development life cycle definition. it is a period, which starts with making a decision that a new software product is necessary and ends when the product is no longer used. Explaining SDLC meaning in simple words, this is a sequence of steps required for launching a product and supporting it.

The roots of the software development get back to the 1960s. Over 60 years of evolution with extremely rapid changes over the last two decades resulted in a wide variety of development strategies, methods, and of course software development life cycle models. We aren’t going to explain each of them, but here are some of the most used SDLC phases with examples of advantages and disadvantages.

Software development lifecycle methodologies

  • Waterfall Model
  • V-model
  • Incremental model
  • Spiral model
  • Agile model
  • DevOps model
  • Rad model

Waterfall Model

Waterfall model is a sequential one which divides software testing and development into sequential phases in which each phase is designed to perform certain acts.It’s simple and idealistic and serves as the base for many models that are being put to practice at present. A classic waterfall model divides any project into a set of phases. One phase can only start when the previous phase ends.Let’s have a look at the different sequential phases in a waterfall model.there are Requirement Analysis , System Design , Implementation, Testing ,Deployment and Maintenance.


  1. Phases are easy to maintain since they are rigid and well-constructed.
  2. Specification change can be made easily.
  3. The requirements aren’t altered during the process.
  4. Milestones and deadlines can be defined clearly.
  5. Opportunity to plan deadlines and resources accurately.


  1. Many testing models incorporate testing to the process on the other hand waterfall model movies away from testing
  2. Lack of adaptability
  3. The testing starts only in the middle of the project.


V-Model is the second linear sequential approach for software development. It’s a kind of extension of the Waterfall Model. This SDLC sequential approach of V-model demonstrates the relationships of each development phase of development life cycle with it’s associate phases of testing. V-Model is a disciplined approach and the next phase can be started only when the completion of the previous phase has been done. It’s also known as the Verification and Validation Model.

V -Model found its identity and name because of its looks and design, as this approach was designed in the form of alphabet V, due to which its known as this sequential SDLC V-Model, the corresponding testing phases of each development phase are being planned parallely, means the testing phases are being planned simultaneously and parallelly when development of its associate development phases are being planned and executed.V-Models are divided into two sides or parts which is called Verification and Validation, One Side of V-Model is known as Verification and another side known as Validation, the Coding phase is one who joins both these parts of V-Model.


  1. Simple and easy to understand and linear for use
  2. Provide a structured for of approach to develop software
  3. Suitable for small projects where requirements are well cleared and understood
  4. Linear sequential approach as phases can be processed and completed one at a time
  5. Low cost


  1. Not a changes friendly approach
  2. Poor resource allocation
  3. Not a good approach for complex software development
  4. High amounts of risk and uncertainty with in this approach
  5. Requirements should be very crystal clear

Incremental model

In this process the requirements are broken down or divided into multiple standalone modules of software development cycle. Each iteration passes through the requirements, design, coding and testing phases. Iteration accord to the merriam-webster website is the repetition of a mathematical or computational procedure applied to the result of a previous application, typically as a means of obtaining successively closer approximations to the solution of a problem. Each subsequent or follow up release of the system allows for the additions of function to the previous release until all designed functionality has been implemented.


  1. Less costly when compared to others.
  2. Changes can be done Thorough the development stages.
  3. Errors are easily identified.


  1. The requirement of a good planning designing is needed.
  2. Lots of time is spent and consumed rectifying a problem in one unit which requires correction in all the units.
  3. Challenges might be cause due to system architecture as such not all requirements collected up front for the entire software life cycle.
  4. Each phase is rigid meaning unable to bend or be forced or flex out of shape and does not overlap each other.

Spiral model

The spiral model combines elements of an iterative software development model with a waterfall model. It is advisable to use this model for expensive, large and complex projects.In its diagrammatic representation, the spiral model looks like a coil having many cycles or loops. The number of cycles varies for each project and is usually specified by the project manager. Each spiral cycle is a stage in the software development process.The Spiral Model allows the product to be rolled out and refined in each phase of the spiral, with the ability to build prototypes in each stage. A prototype is created at the beginning of each phase as a risk management technique.


  1. Changing requirements can be accommodated.
  2. Allows for extensive use of prototypes 
  3. Requirements can be captured more accurately. 
  4. Users see the system early. 
  5. Development can be divided into smaller parts and more risky parts can be developed earlier which helps better risk management.


  1. Management is more complex. 
  2. End of project may not be known early. 
  3. Not suitable for small or low risk projects and could be expensive for small projects. 
  4. Process is complex 
  5. Spiral may go indefinitely. 
  6. Large number of intermediate stages requires excessive documentation.

Agile model

Agile methodology is a type of project management process, mainly used for software development, where demands and solutions evolve through the collaborative effort of self-organizing and cross-functional teams and their customers.

Stemming from the values and principles of the Agile Manifesto, it was created as a response to the inadequacies of traditional development methods such as the Waterfall method. The software industry is a highly competitive market due to the fact that software is something that can be continuously upgraded. This means that developers need to constantly improve and innovate their products to keep on top of the game and the linear, sequential approach of the Waterfall method just wasn’t cutting it.


  1. Provides more flexibility.
  2. Agile model provides customer’s satisfaction at each iteration.
  3. No issue of bugs.
  4. Can change or modify the requirement very easily.
  5. It reduces development time of software product.
  6. This model saves time.


  1. It takes a long time to complete a project.
  2. Agile model requires too much involvement of customers.
  3. This model does not define end point clearly.
  4. It can be more cost effective.
  5. Developers and testers have to work actively.
  6. This model is difficult to implement.
  7. More risk of maintainability.

DevOps model

The DevOps methodology is new to the SDLC arena. DevOps emerged from two trends: the application of Agile and Lean methodologies. These models were used by operations teams. The emphasis here is on valuing the cooperation between the development and operations personnel throughout the SDLC process.In a DevOps model, the developers and operations teams collaborate closely and sometimes as one team to hasten innovation and the delivery of higher quality and more reliable software products and functionalities. There are small but frequent updates to products. The hallmarks here are discipline, continuous feedback, and process enhancement.


  1. There is a steep learning curve involved in getting internal teams productive. Consulting companies would have good general skills.
  2. Hard to hire good DevOps engineers. Lots of them are sys admins and operators who cannot code or who don’t understand infrastructure and systems, depending on their background.
  3. Experience rolling out DevOps projects elsewhere.


  1. Lack of domain knowledge. This could be a problem if serious integration work will be involved in automation projects.
  2. Expensive. Good companies with skilled consultants would end up charging more.
  3. Pushing their favorite products and processes, which might not fit very well with customer’s env. This could be avoided if customer has knowledgeable leadership.

Rad model

RAD Model is generally based on the prototype model and iterative approach.This model is used to completing the process of software product developing in a very short time.The entire project is divided into various small modules and each module is allocated to different party to finish the working of the small modules. After that, all small modules are combined together to obtain the final project.If your project can be divided into many parts or modules then the Rapid application development model is used.The process of RAD model is building the Rapid prototype and deliver it to the clients and taking the reviews from them . If customer is satisfied then SRS document is created and designing phase is start.


  1. RAD model completes the project in a short period of time.
  2. The progress and development of project can be check on various stages .
  3. This model uses the powerful techniques and tools.
  4. reduce cost because very less developers are needed.


  1. There are no reusable component are used to lead the failure of the project .
  2. This model works only when the requirements are clearly specified.
  3. This model can be more complex if prototype is refined again and again.
  4. RAD model is not suitable for the short projects.

-Thanks for your Reading-





BSc.(Hons) Software Engineering Undergraduate -University of kelaniya-