How do you differentiate between waterfall SDLC models?

The Waterfall model has long running development and release cycles, though it may have worked long ago for the software development, it may not work for the modern period. Because when development has a long running timeline, the entire feature or product will be only tested after the long timeline of the release cycle. So there is a high chance of more bugs and it may cause more time to resolve those bugs, which in turn hampers the product release. This is when the Agile development methodologies make a difference, as it recommends modular, smaller chunks of feature releases. Each module will go under an immediate QA cycle and concepts like CICD automation adds values to each release. Overall it is fail-fast for better product release.

One of my coaches had put this quite life-likely - The Waterfall Software Development Life Cycle (SDLC) model is like trying to build a sandwich one layer at a time, but you can't take a bite until the entire sandwich is complete. So, you start with the bread, add lettuce, tomatoes, cheese, and finally the turkey. By the time you're ready to eat, you realize you should have used ham instead, but it's too late – you've got a turkey sandwich. In Waterfall, you commit to all the ingredients upfront and hope it turns out tasty!??

The Waterfall SDLC model is a linear software development approach with distinct phases: Requirements Gathering System Design Implementation Testing, Deployment Maintenance. Each phase must be completed before the next begins, making it rigid and less adaptable to changes. It's suitable for projects with well-defined requirements and minimal expected changes during development but less suited for dynamic or evolving projects.

The main strength of the Waterfall Model is its simplicity. The model is very useful when a project can actually be divided into watertight compartments. But very few software projects can be divided thus but if it can produce good quality.

The waterfall SDLC model can be likened to a well-structured recipe. In a world of agile and iterative approaches, the waterfall stands as a timeless, step-by-step cookbook for software development. It assumes you have a meticulously crafted recipe (clear requirements) and a patient chef (no changes mid-cooking). While not the trendiest method, it still has its place when the dish demands a carefully orchestrated, no-surprises approach.

Waterfall is best when periods are short. This would greatly minimize the risk. There are a number of cases I have seen when companies combine waterfall and spiral. This combination proves more effective in uncovering and addressing bugs.

Works best for transformation programs and where scope is known, the organization is matured and there is a set budget to accomplish the project. The stakeholders ( Business and IT) can be identified upfront, their time and commitment secured and there is a clear end goal in mind since the inception of the project.

The Waterfall SDLC model provides a structured and well-defined process, ideal for small to medium-sized projects. It ensures clear requirements and scope definition, reducing scope creep. Extensive documentation is a key advantage, in maintenance, and compliance. Waterfall predicts timelines and budgets accurately, It emphasizes quality assurance at every stage, resulting in a reliable final product. Customer involvement occurs mainly at the project's start and end of the phase, suiting situations with clear customer vision. Waterfall is favored in regulated industries due to its documentation and traceability. It's efficient for small teams and stable technologies, with a focus on maintenance and support.

Simple and Easy to Understand: Its linear and sequential approach makes it straightforward and easy to manage. Each phase has specific deliverables and a review process, providing clear structure and milestones. It works well for smaller projects with clearly defined requirements. Reviews and approvals at the end of each phase ensure high-quality deliverables. The plan is clear from the beginning, making it easier to estimate timelines and costs accurately.

The waterfall SDLC model offers the advantage of providing a stable foundation for regulatory compliance and auditing. Its structured phases and detailed documentation align well with industries that require strict adherence to compliance standards, such as healthcare or finance. This can streamline the auditing process, ensuring that the project meets all necessary regulatory requirements without ambiguity or confusion. Additionally, for clients or organizations with a strong focus on governance and risk management, the waterfall model's predefined stages offer a sense of control and predictability that can be reassuring in complex, highly regulated environments.

?The waterfall approach has one fatal assumption: scope is static. ?Scope changes according to technological trends, market demand, and competition. Many times, scope increases to encompass more desires and needs. We call it scope creep. Making this assumption can lead to dissatisfied clients overall. ??To combat that assumption welcome scope changes instead. ??Prioritize scope changes and focus finite resources on the most important ones. ??Leverage agile principles: - collaboration over contract - responding to change

The customer is expected to lock-in their requirements. However in most cases, the general broad picture is known but how that translates and gets realized into a product, that is a journey that evolves in the minds of the owner of the product. While it is no big guess the clearer you are, the better you are in control, but in some realms it is practically not easy and desirable to lock-in. Waterfall model leaves little room for changes/evolution.

Waterfall model is less adaptable to changing requirements or issues discovered late in the project. The changes are costly and time-consuming to implement once a phase is completed. This model is less flexible and has difficult implementation to accommodate changing project requirements.

The waterfall approach is characterized by its limited flexibility, as it doesn't produce any output until the project's end. While it can yield a final product relatively quickly, it often necessitates numerous rounds of adjustments and fine-tuning, which can cause projects to exceed their deadlines. However, a waterfall model is the only viable option in some situations. For instance, in vaccine development, any deviation from the established steps is impractical, and strict adherence to the process is imperative. Similarly, in highly regulated software development environments, such as those in the aerospace or medical device industries, where safety and compliance are paramount, the waterfall model may be the preferred choice.

The risk of failures. It takes long time to test the product so any failures in testing can cause more problems because the context is wide to find the issue. Also there might have already been developed more buggy features on top of the issue.

Would not call Agile 100% opposite from waterfall - it was borne out of waterfall shortcomings for sure, but it is not opposite from waterfall models. You can still have all waterfall phases in Agile but executed in parallel and not waiting for each other as dependency in waterfall. Even though most agile methodologies and frameworks are iterative, there are some (i.e. Kanban) that are not timeboxed and are not well suited for timeboxed iterations but are still agile and adoptive to changing requirements. Continuous improvement and refinement are the key to agility.

Agile and waterfall are not opposites but they are choices in front of a software manager to choose from. Where you have very good clarity of upstream phases such an planning and requirements one should choose waterfall model. In cases where customer feedback is important in developing software, Agile gets choosen automatically.

In a recent study, it was found that Agile projects are 28% more likely to succeed than Waterfall projects. This success can be attributed to Agile's adaptability. Agile projects have 37% fewer defects on average, thanks to continuous testing and feedback loops. Moreover, Agile teams report 40% higher customer satisfaction due to frequent collaboration. While Waterfall may have its merits, these statistics highlight the advantages of Agile in today's dynamic project landscape.

Placing stronger emphasis on value produced rather then scope. Shortening feedback loops and validating if value is being delivered. It's not so much about speed or scope, but rather the direction and hitting a moving target.

Differentiating between Waterfall and Agile SDLC models hinges on the project's requirements and adaptability needs. Waterfall follows a fixed sequence of phases, suitable for projects with well-defined requirements and low volatility. Agile, aligned closely with SAFe principles, employs an iterative approach. It breaks the project into smaller, manageable units, facilitating adaptability and continuous stakeholder feedback. Agile suits projects where requirements may evolve. Selecting the right model depends on your project’s demand for flexibility versus predictability.

Despite common belief, Waterfall is still very much relevant today and I would call it for very large or extremely large projects. For example, ERP Migration project is huge effort - you would most likely want to manage the initiative and define high level deliverables with Waterfall but still have more detailed execution stages run as smaller Agile projects. You really want to have everything defined and scoped in advance with no large surprises down the road - otherwise you would not embark on such large imitative at all no matter how much you want to be agile. Waterfall still fits better for organization that want to know and control the effort and the cost before their projects even start.

Points mentioned above are all relevant and are all key, moreover, resources, skills, and technology used will contribute too.

Scale and product life stage. There are broadly two types of software projects - Products & Custom Software for a single customer. Secondly, what is the size of the software being developed? Thirdly, what is the life stage of the product in question? Are we at the conceptualization stage or are we dealing with an existing software product? The choise of a SDLC is never a simple one. And lets face the facts - 1). Agile, in all it's glory is a Waterfall with smaller time steps and lots of tooling. 2). No software design every survives first contact with the developer's keyboard. 3). Testing & Quality Assurance is always squeezed. Adjustments and compromises are facts of life in the industry.

Again, using the Stacey Matrix, first gather your stakeholders and build consensus, then research the software for it's technical complexity. Score your agreement and technical complexity and multiply them together. If the score is 1-7 use waterfall, if the score is 8-19 use agile. If the score is >19 the project should be delayed, unless you are a startup. Without utilizing clear guidelines many companies attempt projects and fail due to lack of planning be it waterfall or agile. Aligning stakeholders, technology, and the business case is of vital importance for project success.

Selecting the right SDLC model hinges on careful evaluation. Here's what to avoid: 1. Ignoring Project Complexity: Don't underestimate complexity; it can creep in unexpectedly. 2. Overlooking Customer Involvement: Even in Waterfall, client input matters. 3. Neglecting Flexibility: Be open to adjustments if needed, even within a structured model. 4. Budget and Timeline Blind Spots: Watch for scope changes that can impact both. 5. Relying Solely on Tradition: Don't choose Waterfall just because it's familiar. Remember, adaptability within structure is key.

Most crucial would be the early initiation and design stages where you set the goals and objectives and do more detailed requirements gather and design, so that there are no large surprises in later stages. If you cannot afford to clearly document and analyze what is needed in advance, more than likely you will be more successful with Agile and do not attempt Waterfall at all.

Implementing Waterfall effectively involves more than just the basics. To succeed: Do's: 1. User Acceptance Testing (UAT): Engage end-users in UAT to ensure the product aligns with their needs. 2. Risk Assessment: Continuously assess and mitigate project risks, especially in longer Waterfall cycles. Don'ts: 1. Overly Optimistic Scheduling: Be realistic; overly tight schedules can lead to rushed work. 2. Ignoring Feedback: Don't dismiss feedback; even in Waterfall, consider it for future phases or projects. 3. Scope Creep: Keep a tight grip on scope; even minor changes can disrupt the linear flow. 4. Silos of Work: Encourage cross-functional collaboration to prevent silos within phases.

Effectively implementing a Waterfall SDLC model involves clear project initiation, robust requirements gathering, meticulous system design, coding with quality control, comprehensive testing, and thorough documentation. User training, deployment planning, and post-deployment support are essential. Continuous monitoring, change management, and transparent stakeholder communication are crucial throughout. A post-project review and lessons-learned session refine future practices, ensuring successful project delivery.

Large scale software development projects with well defined and stable requirements prefer Waterfall model. There is a lot of emphasis on documentation. Requirements Gathering & Analysis helps to define scope, objectives of the project. Once the requirements are understood, design phase begins which involves creating a detailed design document that outlines the software architecture, user interface, components. Coding of the software based on the design specifications. Thorough testing of the software is quality check to ensure developed product meets the requirements with no defects. Once software is approved, it is deployed to production. Maintenance involves fixing production issues, formally handing it over to the support team.

Agile provides the ability to react faster to issues as they pop up. Perfect for all projects working on existing software products, whether enhancements or maintainence. Agile is perhaps the best way to go during later stages of a software product. Smaller change requirements & negotiable - bite off smaller chunks, easy wins, which keeps the customer happy. Everyone likes a taste of the cake while the baker is busy baking! Brand new development projects? Requirements will never be written in stone. Neither the design below the architecture level. The amount of boilerplate that is a part & parcel of all new development projects cannot be wished away with the choice of SDLC. The trick? Recognize what we are about & adapt accordingly.

I have never worked on waterfall but certainly feel agile is better as it gives team and PO the control to decide what they want to deliver and how much without putting too much pressure on themselves. However, if one doesn’t have a good team or doesn’t have the support that is needed from their organisation , it can be a bit tricky to implement.

It's important to emphasize that while it can be highly effective for well-defined projects, its rigidity can pose challenges in today's fast-paced tech landscape. It's worth noting that hybrid approaches, which combine Waterfall's structure with Agile's flexibility, are gaining popularity. These hybrids offer a middle ground, allowing adaptability in complex projects where requirements may evolve.

Based on my experience, I recommend a hybrid SDLC approach. It combines the structure of Waterfall with the adaptability of Agile. In well-defined projects, Waterfall's detailed planning is valuable. However, the project landscape often changes. Agile components allow you to pivot and respond to evolving requirements. The hybrid approach blends rigorous initial analysis and documentation with iterative development and customer collaboration. It's a versatile solution that adapts to your project's unique needs, offering flexibility without sacrificing essential planning and structure.

Because something is outdated or old, doesn’t mean it’s useless or not useful anymore. Because “old is gold”, we just don’t say it like that. Now, yes, I do agree that Agile and all modern hybrid processes are relatively better in lot of things. But I don’t think choosing only one formula will get you to the successful project or outcome. There are instances where we have only followed waterfall and it has worked fine and in other areas it has failed miserably. So having a calculative, realistic and wholesome approach is more important over selecting waterfall or agile.