Agile Vs Waterfall - What is Agile Methodology and Waterfall Methodology?

What is Agile Methodology?

Agile is a group of software development processes that promote evolutionary design with self-organizing teams. Agile development inspires adaptive planning, evolutionary development, and early delivery of value to your customers.

The word “agile” was first associated with software development back in 2001 when the Agile Manifesto was written by a group of visionary software developers and leaders. You choose to become a signatory on the Agile Manifesto website, which stamps your intention to follow the principles.

Unlike traditional development practices like Waterfall, Agile methodologies such as Scrum and Extreme Programming are focused around self-organizing, cross-discipline teams that practice continuous planning and implementation to deliver value to their customers.
The main goal of Agile development is to frequently deliver working software that gives value. Each of these methods emphasize ongoing alignment between technology and the business. Agile methodologies are considered lightweight in that they strive to impose a minimum process and overhead within the development lifecycle.

Agile methodologies are adaptive, which means they embrace and manage changes in requirements and business priorities throughout the entire development process. These changes in requirements are to be expected and welcomed. With any Agile development project, there is also a considerable emphasis on empowering teams with collaborative decision-making. In the previous chapter, I talked about how the Waterfall-based development process follows a set series of stages, which results in a "big bang" deployment of software at the end of the process.

One of the key ideas behind Agile is that instead of delivering a "big bang" at the end of the project, you deliver multiple releases of working code to your business stakeholders. This allows you to prioritize features that will deliver the most value to the business sooner, so that your organization can start to realize an early return on your investment. The number of deliveries depends on how long and complex a project is, but ideally you would deliver working software at the end of each sprint or iteration.

What is Waterfall Methodology?

The Waterfall process is split into separate stages, where the outcome of one stage is the input for the next stage. In the first stage, Requirements Specification, all possible requirements for the system to be developed are captured and documented in a requirement specification document. This document normally requires sign-off by key project and business stakeholders.

This part of the Waterfall model is typically organized by the business analysts, but depending on the size of your project, team, or organization, other members of your development team may be involved. This stage is about teasing out the requirements of the system from your stakeholders. This would include the required functionality, documentation of business rules and processes, and capturing any regulatory and compliance requirements that will affect the overall system.

The next stage is System Design. The requirement specifications from the first stage are inspected, and the system design is put together. This design helps in specifying the system design requirements, and also helps with designing the overall system’s architecture. It is this stage where architects, solution designers, and developers will work together to decide how the overall system will be constructed. This is from a code perspective, and also a technology choice and infrastructure perspective.

The next phase is Implementation. This is the phase where the developers take the design and start producing code to turn the design into a reality. The developers may also write automated unit and integration tests at this stage.

After the Implementation phase, we have the Integration and Testing phase. This is where all the deliverables from the implementation phase are brought together and tested as a whole. The testing team should be working to a defined test plan. Once the system has been tested and signed off by the test team, the next stage is deploying the solution to your end users. Your end users may be internal customers within your organization, or customers.
Once the solution has been deployed, it goes into the Maintenance phase, where any issues that are reported will need fixing and re-deploying. This would generally be in the form of release patch fixes to your system. You may also perform small enhancements to the system at this phase. If an enhancement is quite large in scope, then you might start the Waterfall process again and start capturing further requirements.

All of these phases are cascaded, where progress is seen as flowing steadily downwards like a waterfall. The next phase is started only after a pre-defined set of goals are achieved from the previous phase. In this model, the phases do not overlap.

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