Software Development Life Cycle(SDLC), is a breakdown of the systematic steps involved in creating software products. It is the complete cycle of software production from planning, coding, and testing to deployment and maintenance. SDLC adapts traditional business practices to improve operations and produce better results by defining a roadmap for each phase of software development. It typically segments operations into 7 phases. They are planning, defining, designing, building, deployment and maintenance.
This article discusses SDLC methodologies and six of the top SDLC methodologies as outlined below.
SDLC methodologies are development models that provide the frameworks needed to approach and implement the Software development process. They have different principles and methods which may sometimes overlap and are best suited to varying requirements and circumstances.
Waterfall is the oldest PM model. It is a linear sequential model named after its sequential structure.
In this model, the operation takes place step by step, and each phase of the project is completed before proceeding to the next. Each phase is dependent on the output of the previous step, and completed phases will not be returned to. A visual representation of this model is the downward flow of an actual fall, down a cliff. The water flows downward in a step-by-step manner, and cannot flow backward onto a previous step.
The waterfall model focuses on three core principles. They are
To begin a waterfall procedure, all documentation is extensively done upfront. This information is gathered from clients on their expectations of a final product. It is the foundational stage of the SDLC.
This is the second phase of the project, where the requirements are reviewed and analysed to generate the design needed to arrive at production. This design phase is implemented through two subunits ;
Logical Design: This is where the theoretical questions and answers are formulated. The ideas and philosophies to be employed are discussed, as well as potential problems and their solutions.
Physical Design: Here you begin to specify the hardware, software and general inventory required to bring the ideas to life.
Following the conclusion of analysis and design, this phase is where production(coding) begins. It has only one focus; construction of the product based on the information gathered and the guidelines laid down in the requirement and design stages.
For larger scale projects, team members may work on small production units, the outcome of which are tested before integration to the overall product.
To ensure that all customer requirements have been met, the product will be thoroughly tested for bugs. Minor flaws may be fixed by a forced repeat of the coding stage, which is commonly known as ‘debugging.’ Major flaws however, will result in a restart of the entire waterfall process.
Once functionality, security, user-experience and other requirements have been validated, the flow proceeds downward to the next step. Also customers can be invited for testing and input at this stage, under a User Acceptance Test agreement.
A fully verified product is deployed as intended, and then maintenance follows it up. Maintenance is an indefinite process that comprises corrections, and adaptations through updates. It is also common for users to detect bugs that are only identifiable in the client side environment. Maintenance makes sure that the users remain satisfied with the product.
The Waterfall model is best suited for projects where :
Agile is the software development approach that is defined by breaking down projects into small, flexible and incremental units, as opposed to a single massive launch. Agile model aims to provide value through receipt and integration of exhaustive customer input, which is made easy by its flexibility, adaptability and continuously iterative nature. Agile development cycles are ever evolving, overlapping and always improving. Agile prioritises:
Agile is a set of values and principles that divide tasks into smaller, manageable and quickly adaptable iterations that do not require long-term planning. It bases operations on defining a product user, and a vision statement that identifies the problems, demands, or requirements to be met for that user.It can implemented through a set of frameworks. These frameworks provide the tools, and roles to implement agile principles. Some of them are ; Scrum, Kanban, and Extreme Programming.
Scrum is a popular agile framework focused on managing tasks within a team-based environment to deliver and sustain the development of complex products while encouraging teams to learn and continuously improve through failure.
Scrum is tailored to incorporate adaptation to changes and user requirements. Tasks are broken down into short one to two-week cycles which are called Sprints.
Kanban is a simple, visual process used to track and manage projects. It involves the use of a board that clearly depicts the progress of each workflow in 3 sections marked “To Do,” “In Progress,” and “Done.”
Extreme Programming focuses on using continuous development to improve customer delivery and satisfaction. It employs short quick work cycles or sprints similar to scrum. XP incorporates teamwork, communication, and feedback to develop better results.
Agile methodology is a beneficial model if your project falls under the following categories:
DevOps is a blend of software development (Dev) and IT operations (Ops). This model combines development and operations teams in the organisation to optimise cross-team communication, productivity and high-speed delivery throughout the entire SDLC. Its goal is to provide high-quality software in a shortened systems development lifecycle. This model centres on :
Before arriving at the different phases of the DevOps SDLC cycle, your organisation should essentially install the following practices:
The first step in implementing DevOps is to establish a unit dedicated to and responsible for the DevOps team, strategies, activities, and resources.
CI/CD represents Continuous Integration and Continuous Delivery. It uses automated testing to ensure continuous iteration and effective deployment, software quality and security, and it also increases the production, addresses configuration management challenges.
Automation speeds up the testing process by minimising repetitive processes. It enhances test efficiency, aiding early bug detection before application deployment.
The final step of this process is to ensure continuous tracking and assessment of product development progress and employee performance. This can be optimised through use of automated dashboards.
Once the above structures have been established, DevOps SDLC can begin, usually following these phases:
The planning stage is where you determine workflow, strategy, tools, and team members for the SDLC.
This is the stage where production commences. Code development, source code management, code merging and reviews take place to manufacture the product.
To verify that the software built meets requirements, it should be thoroughly tested for bugs and deficiencies:
After satisfactory testing and successful verification, the application is made publicly available for users.
After deployment, the application’s performance is evaluated and monitored for bugs that may surface, and to enhance continuous improvement.
DevOps is ideal for you if you need :
The lean model focuses on optimising effort and resources to create value for the user. It is characterised by eliminating waste, making decisions as late as possible, and delivering outcomes as fast as possible while focusing on the big picture. So you could say Lean methodology is a game of absolutes.
The model is built on two pillars, which are:
Because Lean users utilise every opportunity to minimise waste at every given instance of the cycle, it is often reported that the aim of this model is to eliminate waste. However, the desire to cut away waste is merely a byproduct of the unnegotiable goal of creating value. In the Lean SDLC, whatever fails to provide value to the end product is cut off, hence the emphasis on waste elimination. Lean provides this value from continuous learning and respect for people. The Lean model believes in shared responsibility and lightweight leadership while following a defined roadmap.
This allows everyone to have a say on ideas, methods, and solutions . Respect for people is characterised by seeking to learn from frontline workers who have hands-on experience with the products and sometimes customers, as well as the customers themselves.
The cycle starts by identifying everything that adds value to the product - the customer defines value. Next, every process or resource that does not benefit the customer directly is deemed unnecessary and cut off.
The value stream visualises the product's life cycle from research and development to the customer's use. This step is vital to achieving maximum value and waste reduction. Therefore, the team vigorously examines every process to determine its value.
To successfully implement Lean methodology, the flow of work should be smooth, with every process seamlessly syncing with all others.
Pull means making nothing unless there is a demand for it. This way reduces overproduction and shortens production time.
Lean practitioners strive for perfection as the goal of continuous improvement. They relentlessly conduct further studies to understand and solve problems, making incremental changes and reducing waste. Examples of waste include:
The Lean model is ideal for various applications and scenarios, especially if :
This model uses predetermined requirements and basic features to build a base software. This initial model is a cheap, rapidly developed product, which is then adapted and upgraded subsequently with features as new user requirements are identified. It is a cyclic procedure that revisits and repeats stages, however, required to improve the product and iterate new features.
The iterative methodology goes through similar implementation phases as the waterfall model, only in a different order. Below are the steps it typically follows:
In this phase, iteration requirements are compiled and assessed to identify a clear goal.
Here, designs and technical solutions are created to best conceptualise and implement the requirements. to implement the requirement out of many alternatives.
The implementation stage is where coding or development begins, with the aim of giving life to the requirements and designs. This phase may involve prototyping or unit testing at the developer’s discretion.
This is the debugging stage, where flaws and loopholes are identified and remediated to meet customers' requirements.
This stage involves a comprehensive review of the final iteration to determine that it meets standards and requirements.
This model functions best in cases where:
Spiral model combines the repetitive concept of the iterative model with the structured linear approach of the waterfall model. It lays emphasis on risk analysis and management. This means design and architecture are applied only to areas with the lowest possibility of failure. The visual representation of the Spiral model is a literal spiral, with each loop representing a phase of the SDLC.
In this phase, operations begin with the compilation of customer requirements to define and analyse objectives and proffer possible alternatives. It includes cost estimation, establishment of a timeline and understanding the system requirements for continuous communication between the system analyst and the customer.
Here, possible solutions are reviewed and the best fit for the project is chosen. This solution is then assessed to identify the associated risks, such as cost overrun, operating cost miscalculation, and schedule slippage. Then the team develops the best possible strategy to mitigate these risks.
After risk analysis, the next stage starts by building a prototype of the agreed-upon strategy. This phase involves coding and testing to create a product version that meets requirements. After verification, the product is made available for customer evaluation.
The user evaluates this first version and returns feedback. Then, based on the customer assessment, the product undergoes incremental iteration, developing new features. These iterations remain continuous through the life cycle of the software. Next is to identify additional risks and monitor them.
The spiral methodology is ideal for projects where;
It's important to stress that the methodologies discussed above are NOT all the available models, but instead six of the best. Each model follows its unique steps, rules and principles increase quality of software development. They all have their pros and cons, and preferred environments where they excel. To maximize benefits and minimise limitations, proper research should be conducted to determine the best methodology to employ.
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