Most used Software Development Life Cycle
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Lean, Agile, Kanban, Scrum, and waterfall are some of the most used words for software life cycle development. But, what is the meaning of these words, and what is their relationship with each other? This article will take you through the life cycle of software development evolution and touch on the various recent trends.

Software Development Life Cycle

Software development life cycle is a process of software engineering that can be adopted in designing, developing, testing, and deploying software. Each step provides businesses with software development control by providing anticipatable deliverables and transparency into schedules and budgets. The purpose of implementing the SDLC paradigm is to generate better quality software efficiently and productively at a lower cost. Lately, the waterfall and the agile-based methodologies are the most commonly used SDLC models in software management.

The Waterfall Software Development

Waterfall development established early in the 1970s was the first model implemented to handle software development. Linear-sequential development cycle applied in this model, in which each step is distinct and can only begin if the previous one is complete. Developed by the construction and manufacturing industries, it includes a process that, just like a cascading waterfall, flows from top to bottom.

Below are SDLC phases identified by Winston Royce, who is the creator of the waterfall model.

Requirements. It is the only phase where customers are involved until the software is complete. It includes gathering all the customer requirements.

Design. It is the architecture stage of the software that includes both the physical and logical designs

Implementation. Hinged on the specs from the design stage, in this step, developers generate test codes. 

Verification. At this stage, customers review the software to see if it meets their requirements.

Maintenance. It is the last stage that involves maintaining the product. Fixing any security vulnerabilities takes place here.

No matter the size of the release, the release-time averages between one to two years with the traditional waterfall model. Consider the days before SaaS Excel, when significant updates involved a product's new reevaluation and only happened once in two years.

The waterfall model is easy to manage since it offers a standardized and centralized approach to software development. But, unfortunately, its product changes are too expensive, making it non-responsive to the customer changing requirements once the development team passes the design stage. 

The agile software development

Agile software development published in the year 2001 leads to the upending of software development. It consists of twelve guiding principles that mainly focus on leadership, group work, and client satisfaction. Some core principles are as stated below:

Clients satisfaction through timely and frequent software delivery

One-on-one communication is so efficient and effective.

Change is possible at any level of development.

Being simple is critical

The most outstanding achievement of the agile model was reduced development cycles. Small businesses took the lead in implementing the agile methodologies. That is since they could set themselves apart by promptly responding to client requests for extra features in a far quicker timeline. Medium-sized businesses started to understand the value of implementing an agile strategy, and enterprise corporations gradually followed.

A software firm that practices agile has an average release cycle of every two weeks. Twitter and Facebook, for example, update new software after every two days. But, without a doubt, some organizations release software even more regularly.

It's all about optimizing the clients' added value and being lean when it comes to agile. It has all of the essential steps of a waterfall but in tinier portions. In addition, contrary to the waterfall, the different phases of SDLC in an agile methodology can operate in parallel. Thus it is more sensitive to changes in the market.

The agile methodologies for SDLC

Agile, as previously stated, is more of an attitude than a model. However, several agile methodologies take a sequential approach towards development and aim at improving communication, market speed, and customer satisfaction. The five most known ones are as stated below.

Scrum. It is the most popular. It mainly concentrates on smaller groups of developers made of less than ten members.

Kanban. The lean methodology, named after a Japanese Kanban board, concentrates on analyzing loads of work in which work pulling occurs when capacity allows instead of pushing it to developers.

Extreme programming (XP). It has four primary activities that include testing, designing, coding, and listening. Thus, it lowers the expense of changes and improves productivity due to its many short development cycles.

Crystal. The model is adaptive, very light, and human-powered. It states that the way of communication between people has a high impact on the project. Thus, it emphasizes the interaction between humans rather than the tools and processes.

Lean development. The strategy derived from the manufacturing of lean has seven principles: optimizing whole, respecting people, delivering fast, defer commitment, creating knowledge, building quality, and eliminating waste.

These approaches, however, have similar objectives despite their differences., the purposes include increased responsiveness to market changes, improving client satisfaction, unity across engineering, an improvement on communication, and lowering costs.

Waterfall-agile hybrid software development

Both agile and waterfall have their weaknesses and strengths when put into practice. Even though waterfall has longer release cycles than Agile, it has a more predictable timeline and budget since its scope is clearly defined. On the other hand, Agile is highly responsive to changing consumer requirements and market conditions. However, it costs developers high taxes, and it makes it hard to plan for long-term projects.

Many software companies adopted the hybrid approach to balance the limitations of each technique. The aim here is to combine both methods: execution and communication of agile with waterfall planning.

Teams use this strategy to implement the waterfall-style structured upfront planning process. Agile comes into effect after scaling down waterfall planning into tiny development chunks to efficiently deliver new features to consumers. This method provides structure as well as speed. 

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