Agile Software Development Lifecycle (SDLC): Phases and Methodologies Explained

Let's face it: you want your product as fast and as good as possible. You don't have time to wait long enough to ensure that the product lacks any errors. But let's say you wait anyway. A month goes by, a few months, six months, and then it turns out that your finished product is faulty and needs fixing, which again takes time and money. It turns out that, therefore, the time to market is postponed indefinitely. Not very reassuring, is it? We know how discouraging it can be. What's more, we know how to avoid such a situation. Agile software development is what it's called.

Agile software development allows you to more accurately meet the rapidly changing needs and demands of your customers, stay one step ahead, get software faster than planned, and with higher quality than expected.

The Agile Software Development Life Cycle (SDLC) methodology is iterative and repetitive, so you get control of the whole process, can make changes at any time, and get the MVP at the end of each sprint, which averages 2-4 weeks. You no longer have to wait six months before you can assess the quality of your project. The Agile SDLC reduces time to market and helps you maintain control of the process.

That's right, we started with trumps to let you know that Agile SDLC is a good fit for your business. Learn more about the benefits of Agile software development below.

Agile Software Development: what this means, why choose Agile

The idea of Agile as a software development methodology dates back to the 1990s. But it was officially introduced in 2001 as a software development method aimed at ensuring rapid product creation and continuous improvement throughout the development process. Then the Agile Manifesto was formulated, in which a group of developers shaped the principles of this development method. Today there are many Agile methodologies, each of which meets these principles in its own way and is applied to projects of different scales.

Agile Project Management Philosophy

One of the key concepts of the Agile approach is to provide flexibility. That is, the software solution is developed in small steps, in stages, which allows through continuous iterations to implement the software, constantly improving it.

The hallmark of Agile is that the next stage of development comes only after the previous one is completed. Unlike traditional software development practices, which are time-consuming as they require considering and anticipating from the outset all requirements that may arise in the future, Agile releases the product in cycles. Such cycles are called sprints.

Within a sprint, a team goes through a cycle of steps, from determining the scope of changes needed to analyzing, designing, developing, testing, and releasing the product. Each such cycle (sprint) can last up to 1 month, but its length and structure vary greatly from team to team.

At the heart of the Agile Project Management Philosophy is the incremental and repeatable development of a software solution, in which decisions are made through the interaction of cross-functional teams. It encourages constant change and adaptation to changing requirements. That is, with each development cycle, the team delivers a new version of the product based on predefined requirements.

So why is there an Agile method? We can see it as a response to the shortcomings found in traditional development methodologies. For example, Waterfall meant creating a big project plan and its consistent implementation. Whereas Agile focuses on the following:

• Process segmentation;
• Phased development;
• Continuous communication and adaptation;
• Achieving a high-quality product.

Sounds good, doesn't it? It does, but let's take a closer look at this issue.

Key principles of the SDLC for Agile philosophy

Phased (incremental) development

Planning is kept to a minimum, tasks are divided into small intervals (sprints), cross-functional, self-organizing teams are involved, able to cover all stages of development simultaneously (requirements gathering and analysis, design, development, testing). Phasing avoids risk and quickly adapts to changing requirements, tasks, or unforeseen circumstances.

Tight collaboration within the team

The Agile software development method implies the involvement of the customer representative in the process and his/her close cooperation with the team. The customer representative answers the developers' questions, thereby speeding up the process. To keep abreast of changes and intermediate results, the customer can also use software, such as Jira and similar tools.

Daily feedback sharing

One way to reduce time-to-market and development budgets is to hold regular team meetings. At these daily meetings, team members report within 15 minutes on the completed and planned scope of work, which not only keeps things consistent, but also increases the chances of getting the most viable product.

Quality at the core

Agile methodologies provide a wide range of tools and techniques aimed at improving product quality. These include test-driven development and domain-driven design, unit testing, pair programming, continuous integration, etc. Automated systems and tools are preferred as they save time and eliminate the risk of human error.

Agile Software Development Lifecycle Phases

We talked about SDLC above, so it's time to define the term. At its core, SDLC is a way of organizing the stages/phases of product development to streamline the development process and, as a result, increase its efficiency. SDLC involves using a set of specific tools, methods, and approaches to implement each phase of development.

The SDLC process defines and sets the path, the pace of tasks and their alignment with each phase.

Key Agile Methodology Steps

The good thing about the Agile SDLC is the ability to initiate iterations in the middle of the product development process, without waiting until the project is complete. The Agile software development methodology includes steps such as concept, inception, construction, release, production, and retirement.

Concept phase

This is the very first stage of development, where the business analysis is carried out. This is where the vision for the product is formed, as well as the expected benefits to the business and the results that the company can expect from the development of the product. The Concept phase also determines the budget, time, number and specialization of people needed to create the product. It also determines whether the project is feasible, how product development should be carried out, and what additional resources may be needed. Goals should be clearly defined at this stage so that they can be compared to the roadmap and ensure that the product being developed meets the needs of the enterprise.

Inception phase

This is the stage where product planning takes place. A methodology is chosen, functionality and a set of product features are described, and a list of actions and expected results are defined. Next, all of the above is broken down into user stories - that is, all of the things that users have to do with the application. All of this is described in the following formats: "the user orders" or "the user clicks the buy button and goes to the basket page," etc. The Inception phase involves building a team and understanding its bandwidth and capabilities.

Project Initiation phase

This stage initiates the product development process itself within the chosen Agile methodology and according to continuous feedback loops. The Project Initiation phase aims to obtain a minimum viable product, which in the following phases is revised, evaluated, tested, and finally gives an idea of what the final product should look like. This phase is divided into several sprints (development cycles).

Testing phase

At this stage, the MVP from the previous stage moves on to the Production stage, documentation is created, and the product itself is subjected to quality assurance (QA), user testing, which helps to identify possible errors, inconsistencies and defects. If necessary, an additional development and testing phase is conducted.

Deployment/Production phase

When the product has been tested, it is ready to be deployed on servers and delivered to the customer. It is important to understand that you can deploy both the final version of the product and its beta version, during which product and user behavior is closely monitored to see what needs to be fixed or improved. If it turns out that the product needs additional improvements, you can even start a new development cycle. Be prepared for this turn of events. But it's all worth it if the goal is to meet the project goals and improve the usability of the product. This is why there is ongoing software support during the Deployment phase. The Production phase comes to its logical conclusion when the product is to be retired.

Retirement phase

At this stage, the feasibility of the product (application) maintenance is assessed. If there is no such feasibility, for example, the product does not solve the assigned business tasks, or its maintenance is too expensive, the decision is made to retire it and all related end-of-life activities are performed. In this case, the development team discontinues application support. Another option: the product analysis shows that it can be improved/refined to achieve other goals. If the product is to be retired, users/clients are notified of this decision.

Agile Software Development Sprint Planning

The Agile SDLC is based on iterability. Each iteration results in another component of the software product, which eventually - with each iteration - add up to a complete product. Each iteration follows established sprint principles, namely the following sequence:

• Plan Creation/Requirements Gathering. During this phase, the team discusses plans and goals for the upcoming sprint, identifies relevant requirements, and outlines an action plan based on feedback from the customer, users, and all stakeholders.
• Development. The defined and agreed requirements and tasks are implemented during the software solution development.
• Testing. Development results are tested, performed actions and results are documented.
• Delivery. A ready product is delivered to the customer and users.
• Feedback gathering. Gathering and analysis of customer and user feedback to form the next scope of requirements.

The whole process is repeated in a circle - step by step - until all of the originally established and updated requirements have been met.

Key Agile approaches are incremental and iterative.

As you can see from the above, Agile lives up to its name and provides and keeps the process flexible.

Top 5 Agile Software Development Life Cycle Methodologies

There are many different Agile methodologies, and each aims to deliver the finished product as quickly as possible while successfully adapting to change. And at the same time, the process by which each individual team works on each individual product can run differently.

This is what Agile methodologies have in common:

• They're based on similar ideas, yet they implement them differently;
• They deliver working code iteratively;
• The process involves self-organizing teams;
• There is close interaction with the customer;
• Changes can be made late in the process.

Because of their similarities, many methodologies can be combined, borrowing elements of each for use in the same project. For this reason, it is already difficult to see a clear difference between the methodologies - their elements are often intertwined to achieve a better result. But this is the advantage of Agile methodologies - they are easily compatible with each other.

It's worth saying that those following Agile methodologies often exaggerate their importance, ignoring their obvious shortcomings.

Nevertheless, Agile methodologies have some nuances to consider, namely:

• They are not suitable for large-scale, corporate or distributed development, where developers cannot work face-to-face within the same team;
• They are less suitable for working on fixed-price projects and with embedded systems;
• The constant flow of rapidly changing suggestions and ideas due to user feedback can lead to frequently changing requirements and, as a result, confusion.

All the above features of Agile methodologies should be considered when choosing specific development methods. And also remember that not all methods are agile, even if this term is mentioned in the name of the methodology.

Among the most widely used Agile methodologies are the following:

• Scrum;
• Extreme Programming (XP);
• Kanban;
• Feature-Driven Development (FDD);
• Disciplined Agile Delivery (DAD).

Scrum

Scrum is one of the best known, as well as one of the most clearly defined and specified Agile methodologies. This means that Scrum has a lot of consistent documentation and a well-defined, structured teamwork process, which, therefore, eliminates the likely difficulties in adapting this methodology.

But here's the thing: Scrum's greatest strength is also its greatest weakness.

The features of Scrum are:

• clearly defined roles;
• tight deadlines;
• short iterations;
• quality product delivery as a result of each sprint;
• daily meetings.

On the one hand, such features of this methodology are supposed to simplify the work on the product within the team. On the other hand, for inexperienced teams, the Scrum methodology may seem alien and difficult to adapt in the early stages by specialists with weak connections within the team and a lack of relevant experience.

For those looking to build their work based on Agile principles, Scrum can be an absolute entry point. This methodology can be truly effective. As with other Agile methodologies, the work here starts with creating a backlog of tasks and requirements to be met throughout the sprint. Requirements and needs will be set and discussed during the work by all stakeholders, they will be changed, used for test cases, measured for results, refined, etc. - all this happens during each sprint, which lasts about 2-4 weeks.

All those tasks left to complete, as well as the progress of the sprint, will be displayed in story point format as a graph. This is done to measure the difficulty or amount of effort required to complete the user's story. Story points must be completed sequentially, and the rate at which they are completed is called velocity. If something has gone wrong in the team's performance, it will be discovered at the team meeting at the end of each sprint. The idea is to improve the project from sprint to sprint.

Key roles in Scrum: Scrum Master, Product Owner, team members. The job of the Scrum Master is to manage the team without becoming a team member while keeping the team focused on the goal of each sprint. The Scrum Master works with the Product Owner to keep the task list up-to-date and ensure that tasks are completed on time. In turn, the Product Owner decides on changes, coordinating them with stakeholders in advance. The Product Owner only prioritizes tasks, without specifying which tasks need to be completed.

Team members perform all of these tasks, which results in the finished product being completed according to specifications. It is the team members who design, code, test and release the product. That's their job, but not the job of the Scrum Master.

Anyway, you can't say there are pure Agile methodologies. For each project, a combination of different methods' features is applied, resulting in a hybrid methodology.

Extreme Programming (XP)

The idea is to use the best programming practices, taking their use to the extreme (as you may realize, hence the name XP). Separately, it is worth noting that the XP concepts are not something revolutionary new, but putting them together with each other offers a brand new experience. The key idea of XP is adaptability: use only what fits into the project, rejecting what doesn't. Gaps can be successfully bridged by combining XP with Scrum.

The traditional principles of XP are broadly similar to those of Agile:

• Requirements are driven by user stories;
• Iterations are short;
• Testing is immediate and continuous - as many types of testing as needed are applied (unit testing, test-first programming, integration testing);
• Refactoring is applied to consolidate separately written pieces of code;
• Constant feedback from stakeholders;
• Full responsibility for the result of the work lies with the team.

In XP, changes in requirements can only occur as a result of the agreement with stakeholders or as a result of ongoing team discussion. On the one hand, it is beneficial for the end result, as each step is discussed in advance, but on the other hand, such constant discussion among team members makes it difficult to apply XP to complex and large projects. What complicates XP even more is the constant testing. Nevertheless, this nuance is corrected, for example, daily testing is replaced by weekly testing.

As with other types of programming, only what works best for a particular project is taken from XP.

The practice of pair programming, as a form of XP, has proven to be useful. It involves two experts: one writes the code, while the other keeps the big picture in mind and checks the written code for errors and suggests ideas. If the participants of pair programming get used to each other and feel comfortable in such a tandem, the team splits up and a new one is created instead.

Obvious reasons for choosing XP:

• Simplicity: at each phase of work, only current problems are solved by applying the simplest solutions;
• Flexibility: easy to combine with other approaches, especially process-oriented ones.

Kanban

This programming approach can hardly be called Agile, since Kanban is not iterative. The good thing about iterations is that they allow you to simulate the product/project lifecycle on a reduced scale. Also, each iteration has a clear beginning and a specific end. Kanban, unlike the iterative approach, implies that a software solution must go through a large development cycle. What, then, do Kanban and Agile have in common?

It's all about the Kanban principle, which deals with limited bandwidth. Tasks within the Kanban approach are performed incrementally. Each work item is executed from a predefined list of prioritized requirements. The finished work item does not move on to the next step until additional capacity is available. Kanban allows you to control the number of tasks and manage the actual ones, allowing you to create the product incrementally. If you visualize Kanban, the process looks like this:

The "Work in Progress" stage allows you to keep tasks under control, that is, adhere to deadlines and the general idea of the project.

Unlike Scrum, Kanban does not provide for the distribution of roles among the participants in the process. It is suitable for those teams who are used to working with the Waterfall model and who are still afraid of the abrupt transition to Agile methodologies, which may lead to some confusion among unprepared teams.

Feature-Driven Development (FDD)

Unlike some other Agile methodologies, Feature-Driven Development (FDD) involves the iterative implementation of functionality, but is tied to a functional area rather than to customer requirements.

That is, the design is first created according to the functional areas, and then a clear structure is extracted from that design, which gives an idea of the product's features, which can then start to be gradually implemented.

Some stages of FDD are not iterative, which makes the project less flexible and the method itself different from other Agile approaches. The advantage of this method is that part of the functional area is written at once, so it requires less refactoring compared to code that is expected to change from time to time. Less refactoring is what makes traditional development approaches stand out, thus preferable.

Disciplined Agile Delivery (DAD)

The DAD framework expands the Agile capability. According to its creators, Agile methods cover only those aspects that are directly related to product development, while other aspects, such as hardware, user path, and customer company needs, have been left out. DAD seeks to fill this gap.

This methodology is quite voluminous, and yet here are its key aspects and principles:

• The teams dealing with this Agile methodology are multi-functional and consist of the kind of specialists called generalizing specialists.
• A harmonious marriage of the principles and ideas of different Agile methodologies makes the product creation process more flexible and cost-effective.
• Taking into account enterprise needs in terms of management, vision, teamwork and other aspects of the client's business development.
• Applying methods to assess product viability, eliminate possible risks, and obtain value from the finished product.
• Creating an environment in which learning, adapting to change, and scaling the project are possible.

DAD is still a relatively young methodology, and we have yet to see if it will be widely used because of these features.

Bottom line

Hopefully, it has become clear from this article that Agile methodologies have emerged to replace previously common methodologies such as Waterfall and the V-model. They turned out to be those that resulted in missed deadlines and budget overruns, while Agile proved to be an approach that could eliminate those problems.

However, we must warn you. Don't think of "Agile" as a lifeline. Before deciding on a particular methodology, you should find out its strengths and weaknesses, the stages of the software development process, and your role in all this as well. We've tried to shed light on the benefits of each of the most well-known Agile methodologies and, in general, the Agile software development lifecycle phases, so that you can get the most out of it in the end.

If you are still not sure which Agile methodology to choose, what are the pros and cons of each of them, then please ask us these questions. With as much Agile experience as we have, we are sure we can help you. Drop us a line, we'd love to hear from you.