Blog/Agile
Top 6 SDLC Methodologies Explained
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Praise Iwuh
May 23, 2023
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.
- What is SDLC Methodology
- Waterfall Methodology
- Agile Methodology
- DevOps
- Lean Methodology
- Iterative Methodology
- Spiral Methodology
What is SDLC Methodology?
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 Methodology
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
- Sequential structure
- Minimal customer review
- Robust documentation
Implementation
Requirement Analysis
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.
Design and Analysis
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.
Coding
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.
Verification and Testing
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.
Deployment and Maintenance
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.
Advantages
- Accurate projection of estimated cost and timeline
- A research-heavy approach to the design phase reveals potential errors to avoid during implementation
- Clearly defined milestones and progress due to the structural and planned approach
- Limited input from customers can prevent an overload of suggestions and changes which could derail the basic ideals of the project.
- Detailed, structured, and documented procedures make it easy to replicate.
Disadvantages
- Clients are not involved in the design and implementation stages, which may result in flaws that will be more difficult to correct later on
- A chain reaction of delays. Because the phases are not permitted to overlap, a delay in one phase means all subsequent phases will also be stalled.
- Upfront cost estimation and strict adherence to the schema mean that unforeseen customer demands and their costs might not be accounted for.
- May take longer than other more flexible models
Recommendation
The Waterfall model is best suited for projects where :
- Technology is familiar and well understood
- The project is short and low cost
- Tools and techniques are stable
- Risk factor is minimum
- Resources are readily available
Agile Methodology
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:
- Responding to change
- Customer collaboration
- Working software over comprehensive documentation
- Individuals and interactions over prices and tools
Implementation
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
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.
Kaban
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(XP)
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.
Advantages
- Agile can deploy software quickly
- It can adapt easily to changes and respond faster
- Offers a vast community of Agile practitioners with a wealth of information and resources
- Encourages immediate feedback and implementation
- You can experiment and test ideas because their costs are low
Disadvantages
- It is more difficult to track progress than in linear models
- Projects can tarry indefinitely because overall timelines are unspecified
- Budgets cannot be specified, so cost estimation is difficult
- Sprint durations are too short for adequate design thinking
Recommendations
Agile methodology is a beneficial model if your project falls under the following categories:
- It lacks full specifications and an understanding of the requirements
- It doesn’t have a specified budget
- It does not have a fixed timeline
- You have unlimited access to your customer who's ready for extensive involvement
- You can afford to iterate and don't need to deliver fully functional software at once
- It requires fast, flexible delivery.
DevOps
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 :
- Collaboration
- Data based decision making
- Constant improvement
- Responsibility throughout lifecycle
- Automation
- Failure as a learning opportunity
Implementation
Before arriving at the different phases of the DevOps SDLC cycle, your organisation should essentially install the following practices:
DevOps Department
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 and Automation
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.
Monitoring
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:
Planning
The planning stage is where you determine workflow, strategy, tools, and team members for the SDLC.
Code Development
This is the stage where production commences. Code development, source code management, code merging and reviews take place to manufacture the product.
Testing
To verify that the software built meets requirements, it should be thoroughly tested for bugs and deficiencies:
Deployment and Hosting
After satisfactory testing and successful verification, the application is made publicly available for users.
Continuous Management and Configuration
After deployment, the application’s performance is evaluated and monitored for bugs that may surface, and to enhance continuous improvement.
Advantages
- Promotes collaboration and trust between developers and IT operators
- Increased speed and efficiency due to automation
- Can Increase profit and business growth due to faster deployment time
- Increases customer satisfaction
Disadvantages
- Difficulty in transitioning
- Expensive tools and platforms
- Higher risk rate in deployment
Recommendations
DevOps is ideal for you if you need :
- more transparency and communication between teams
- Seamless production and deployment
- Continuous feedback and integration
- Overall improved quality of coding, testing, and deployment(thanks to automation)
- Increased speed of SDLC
Lean Methodology
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:
- Continuous improvement
- Respect for people
Because Lean users utilize every opportunity to minimize 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.
Implementation
Value Identification
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.
Value Stream
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.
Workflow
To successfully implement Lean methodology, the flow of work should be smooth, with every process seamlessly syncing with all others.
Pull
Pull means making nothing unless there is a demand for it. This way reduces overproduction and shortens production time.
Perfection
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:
- Overproduction
- Unnecessary or unrequired features
- Transportation
- Inventory
- Motion
- Defects
- Overprocessing
- Waiting
- Human potential
Advantages
- Cost reduction by trimming out unnecessary processes, resources and personnel
- The strive for continuous improvement results in customer satisfaction and organisational success
- The pull system improves efficiency because workers only spend time on valuable processes
- Promoting engagements with employees of every status and shared responsibilities guarantees increased commitment to the cause
- Use of only necessary resources results in maximum value extracted
Disadvantages
- Lean methodology prioritises the elimination of resources that are not immediately required. Unfortunately, this leads to over-reliance on suppliers and logistics, which can backfire and result in a shortage of inventory at critical moments.
- Employees may experience difficulty transitioning to this unorthodox system.
- Risk of over structuring because only some processes should necessarily be subjected to this model.
Recommendation
The Lean model is ideal for various applications and scenarios, especially if :
- The project is on a tight budget
- The organization is experiencing a disconnect between the leaders and frontline workers
- The team is struggling with backlog and bottlenecks
- The organization has a need for waste reduction
Iterative Methodology
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.
Implementation
The iterative methodology goes through similar implementation phases as the waterfall model, only in a different order. Below are the steps it typically follows:
Planning and requirement
In this phase, iteration requirements are compiled and assessed to identify a clear goal.
Analysis and design
Here, designs and technical solutions are created to best conceptualise and implement the requirements. to implement the requirement out of many alternatives.
Implementation
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.
Testing
This is the debugging stage, where flaws and loopholes are identified and remediated to meet customers' requirements.
Evaluation
This stage involves a comprehensive review of the final iteration to determine that it meets standards and requirements.
Advantages
- Easily adaptable to user requirements
- Less effort is spent on documentation with more focus on design and development
- Swift feedback after each iteration, resulting in rapid remediation of issues
- Easier testing and debugging thanks to the smaller interactions
Disadvantages
- The process is difficult to handle, and so requires highly skilled management
- It may be unsuitable for smaller projects which cannot be easily broken into units
- More obligations on the user due to frequent engagement
- Design flaws at critically late stages of the cycle
Recommendation
This model functions best in cases where:
- There is a clear understanding of requirements and specification
- The project is large and complex
- The product requires rigorous testing and frequent changes
Spiral Methodology
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.
Implementation
Planning
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.
Risk Identification and Analysis
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.
Development
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.
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.
Advantages
- The high density of risk analysis and handling at every phase improves functionality and security.
- It is ideal for large and complex projects.
- Early interactions with customers allows for their feedback to be sufficiently integrated, and results in their satisfaction.
- It’s flexibility means development is fast and changes can be easily incorporated after development.
- Cost estimation is easy
Disadvantages
- The spiral model is only ideal for large projects
- Its dependence on risk assessment leaves little margin for error and requires absolute expertise
- It can be costly
- This model is more complex than other methodologies and requires more documentation
- It is difficult to accurately predict timelines and meet schedules due to an unspecified amount of phases.
Recommendation
The spiral methodology is ideal for projects where;
- frequent releases are necessary
- changes may be required at any time
- long term project
- risk analysis is critical
- projects that would require prototyping
- the project is large and high-budget
- requirements are unclear and complex
Conclusion
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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