Over the past few decades, there has been a great improvement in software development methodologies. There were traditional developments, such as waterfall development, which were rigid and sequential means, but today, in this world, flexible and iterative ways of agile development are required to match the speed of technical change.
In the modern economy, you start to realize how important it is for business success and how much pressure there is on development teams to ship high-quality applications faster than ever. As a result, there has been a Cambrian explosion of new methodologies to increase productivity, quality and speed.
This article will examine the differences between the old, plan-driven development and the new and more recent agile types. It will cover:
- Key differences in philosophy and values
- Lifecycle models and workflows
- Roles and responsibilities
- Managing requirements and planning
- Testing, integration, and delivery strategies
- Advantages and disadvantages of each approach
- Best practices and key considerations
If you are new to software development or up to using this methodology, you need to learn this to face the modern tech landscape requirements.
Traditional Waterfall Development
Since the 1960s, the waterfall model has been used in software engineering. It is named after the sequential phases of development, and each stage cascades into the next.
Hallmarks of the waterfall approach include:
- Rigid phasing. Requirements, design, implementation, testing, etc., are completed for the entire project in defined stages.
- Upfront planning and documentation. Comprehensive specs, plans, and documentation are created at the start.
- Sequential execution. Each phase has defined inputs and outputs and starts only when the previous phase is complete.
- Process orientation. The focus is on properly following the defined process.
- Role specialization. Team members have clearly defined roles and handoffs between roles.
In waterfall development, the scope, schedule, and resources are determined early, and changes during development can be costly. Extensive upfront analysis is intended to minimize downstream coding errors and rework. Read more on this website.
The waterfall methodology is suitable for requirements that are already stable and well-defined. The advantage of this approach is that it must be rigorous, using the requirements and the risk analysis to develop the rest of the system for big, high-impact projects like defense systems or infrastructure software. The problem is that waterfall methodologies are too rigid and slow when faced with a requirement that is evolving quickly in many modern software projects.
Agile Software Development
In contrast to traditional sequential development, agile methodologies break projects into small increments with minimal planning and embrace change as a normal part of the development process.
The “Agile Manifesto,” penned in 2001, codified many of the shared values and principles of modern agile development:
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding to change following a plan
There are several popular agile frameworks used to put these high-level values into practice:
Scrum
The most widely adopted agile approach. Scrum emphasizes accountability, teamwork, and iterative progress via “sprints” – regular cycles to deliver working functionality.
Lean/Kanban
Based on lean manufacturing principles, kanban boards and visual project management allow teams to limit work-in-progress and deliver value efficiently.
Extreme Programming (XP)
XP focuses on rapid iterations, programmer pairing, test-driven development, and simplicity to enable continuous integration and deployment.
Agile teams cultivate essential testing technical skills but prioritize no upfront planning and documentation bearing limited initial release in the interests of quick release of their software early and often. Rather than a risk to be guarded against, change is welcomed. The customer is closely involved throughout development to provide constant feedback and guidance.
Comparing Traditional and Agile Methodologies
To be clear, there are fundamental differences between a traditional plan-driven and a modern agile approach to software development in virtually every aspect of the process. Let’s examine some of the key contrasts.
Roles and Responsibilities
Traditional development uses a clear diagram of specialist roles – business analyst, architect, developer, tester etc. On the other hand, agile teams are cross-functional, working as a team on the whole stack and having shared ownership.
In traditional teams, each project phase is worked on separately by each team in sequence. Still, the agile team members contribute where and when it is helpful in every sprint, breaking down the siloed barriers that exist in waterfall development.
Requirements and Planning
Detailed upfront project planning is the hallmark of waterfall development. It begins with extensive requirements gathering and design sessions to map out the specifications for the entire project before any coding begins. The goal is to eliminate downstream changes.
Agile methodologies, on the other hand, generally avoid Big Design Up Front (BDUF) and opt instead for “just-in-time” planning. Rather than spending months documenting comprehensive requirements for future-phase functionality, agile teams focus only on defining user stories sufficient for the next sprint.
Development and Testing
According to the waterfall model, the software development process executes a series of steps that include Requirements, design, implementation, testing and release.
These practices (test-driven development (TDD), frequent regression testing (frequent unit testing), and continuous integration manage to keep the developers and the testers tightly coupled. Instead, agile teams deliver incremental working functionality on short iterations to get feedback.
Change Management
Waterfall considers change inherently risky, using extensive planning, documentation, and governance to avoid surprises. Changes to requirements or design can be extremely costly after the initial phases.
Agile development, however, embraces change. The iterative approach expects changes in requirements and priorities. Through the concept of small, frequent releases in place of long-cycle development, the product stays true to customer needs through a number of course corrections.
Advantages and Disadvantages
Traditional or agile methodologies are suitable for different types of projects and product environments. Below, we sum up some general pros and cons of each approach.
Waterfall Pros:
- Works well for mature, stable product requirements
- Rigorous planning and documentation in risk management
- Clear milestones and metrics
- Specialization of roles, formal processes
Waterfall Cons:
- Inflexible to change requests during development
- Limited customer feedback until the testing phase
- Integration issues can emerge late in the cycle
- Long waits between feature deliveries
Agile Pros:
- Embraces, even thrives on change
- Frequent functionality releases
- Early customer feedback informs priorities
- Emphasis on business value vs paperwork
- Continuous integration and testing
Agile Cons:
- Less predictability on schedule, cost
- Lack of documentation
- Dependency on customer interaction
- Inexperienced teams may struggle
- Not optimized for large, complex projects
Best Practices
Agile is newer and more modern, and some of the agile thought leaders claim that neither Agile nor waterfall is inherently better. However, each has advantages that are good for specific projects. Simply put, the best is usually a combination of both methods.
Some best practices that leverage strengths of traditional and agile methods:
Conduct Just Enough Upfront Planning
Don’t neglect BDUF, but limit it without ignoring core architecture and risk analysis activities. Work out what is required for near-term work, but be flexible on the details of future work.
Prioritize Documentation
Agile teams often still utilize UI mockups, API specs, compliance policies, etc., but focus documentation efforts on what adds the most user or business value. Ensure institutional knowledge isn’t lost.
Validate Assumptions Early
Fail-fast principles argue for quickly validating proposed requirements/features with real users or prototypes before making sizable investments in coding.
Automate Testing
Test automation frameworks are used to run the framework for continuous integration and regression testing. By catching defects early, we can release frequent, everyday incremental releases.
Specialization should be retained but supported by collaboration. Agile doesn’t necessarily prevent you from having specialized individual roles, but you bring a broader perspective on the team’s ability to be effective. Foster opportunities for cross-functional interaction and collective ownership.
The Right Methodology Depends…
Each software development methodology is unique and has no standard format. Factors that determine what approach is the most sensible:
- Application type. Each may have a more agile or waterfall strength for business software, infrastructure or embedded systems.
- Project size. Agile can struggle in extremely large enterprise projects.
- Application criticality. Safety or financial criticality may demand more rigorous requirements and risk management.
- Requirements stability. Frequent changes drive the need for more agility.
- Team culture and experience. Agile requires a collaborative mindset from both devs and business stakeholders.
- Organizational norms. Rigid bureaucratic cultures may default to old-school waterfall habits.
Every team and product has unique needs. Unthinkingly following a specific methodology is less important than consistently inspecting and adapting to find what works best for any given situation.
Most modern software teams, even traditionally non-agile organizations, are increasingly incorporating agile practices – even if not adopting wholesale – to accommodate accelerating market and technology changes.
Conclusion
Software development continues to evolve rapidly. While no single methodology is best for all scenarios, agile values like user focus, collaboration, embracing change, and continuous delivery are transforming how modern teams operate.
Indeed, techniques such as just-in-time analysis and planning, test automation, and DevOps workflows are being reintroduced to more traditional processes to speed up and improve quality.
Any new technology leader needs to understand these core methodologies and how they differ in order to manage and further optimize their development teams. Across the full spectrum of processes and tools, traditional and modern teams can select and tailor the ones that best match their culture, project needs and industry constraints to provide maximum business value.
The future is unlikely to settle on a single, defined software development methodology. Instead, it should combine a suit that combines the strength of rigor and agility, the elegance of planning with the effect of adaptation, and consistency with creativity. There are debates as to which school of thought is right, and their debates continue. However, it is likely that more integrated hybrid approaches will evolve in the future by combining strengths and minimizing the limitations of present approaches.
