Agile Development Models – Software Engineering

In earlier days, the Iterative Waterfall Model was very popular for completing a project. But nowadays, developers face various problems while using it to develop software.

The main difficulties included handling customer change requests during project development and the high cost and time required to incorporate these changes. In the mid-1990s, the Agile Software Development Model was proposed to overcome these drawbacks of the Waterfall Model.

What is Agile Model?

The Agile Model was primarily designed to help a project adapt quickly to change requests. So, the main aim of the Agile model is to facilitate quick project completion. To accomplish this task, it’s important that agility is required. Agility is achieved by fitting the process to the project and removing activities that may not be essential for a specific project.

Also, anything that is a waste of time and effort is avoided. The Agile Model refers to a group of development processes. These processes share some basic characteristics but do have certain subtle differences among themselves.

Read More: Software Development Life Cycle (SDLC) Models

Steps in the Agile Model

The Agile Model is a combination of iterative and incremental process models. The phases involve in Agile (SDLC) Model are: 

1. Requirement Gathering
2. Design the Requirements
3. Construction / Iteration
4. Testing / Quality Assurance
5. Deployment
6. Feedback

Agile Model Steps

1. Requirement Gathering

In this step, the development team must gather the requirements, by interaction with the customer. development team should plan the time and effort needed to build the project. Based on this information you can evaluate technical and economical feasibility.

• Meet with the customer to really understand their needs and what they expect from the software.
• Identify the key requirements and business goals to make sure everyone is on the same page.
• Estimate how much time and effort it will take to develop the software.
• Assess if the project is technically possible and whether it’s worth the investment from both a technical and economic standpoint.

2. Design the Requirements

In this step, the development team will use user-flow-diagram or high-level UML Diagrams to show the working of the new features and show how they will apply to the existing software. Wireframing and designing user interfaces are done in this phase.

• Designing the system: Once the requirements are gathered, the next step is to design the system’s overall architecture based on those needs. This helps to verify the software is structured in a way that meets the user’s expectations.
• Creating wireframes: Next, wireframes for the user interface (UI) are created. These are simple blueprints that show how the software will look and how users will interact with it, ensuring it’s user-friendly and easy to navigate.
• High-level design with UML diagrams: At this stage, high-level designs using UML (Unified Modeling Language) diagrams are created to visually represent the software’s structure and how different parts will work together.
• Prototyping for feedback: Prototypes are made to give stakeholders an early look at the software. This helps gather feedback early in the process and allows for adjustments before the full development begins.

3. Construction / Iteration

In this step, development team members start working on their project, which aims to deploy a working product. Each cycle typically consist between 1-4 weeks, and at the end, the team delivers a working version of the software.

• Development of Features: The team works on the features identified during the requirement and design phases.
• Coding and Implementation: New functionalities are coded and integrated into the software based on the goals for that specific iteration.
• Delivering a Working Product: After each iteration, a usable version of the software is ready.
• Incremental Improvement: With every cycle, the software is enhanced, adding more features and refining existing ones.

4. Testing / Quality Assurance

Testing involves Unit Testing, Integration Testing, and System Testing, Which help in the agile development models:

• Unit Testing: Unit testing is the process of checking small pieces of code to ensure that the individual parts of a program work properly on their own. Unit testing is used to test individual blocks (units) of code.
• Integration Testing: Integration testing is used to identify and resolve any issues that may arise when different units of the software are combined.
• System Testing: Goal is to ensure that the software meets the requirements of the users and that it works correctly in all possible scenarios.

5. Deployment

In this step, the development team will deploy the working project to end users.

Once an iteration is finished and fully tested, the software is ready to be released to the end users. In Agile, deployment isn’t a one-time event—it’s an ongoing process. Updates and improvements are rolled out regularly, making sure the software keeps evolving and getting better with each release.

• Deploy the software to a test or live environment so that it can be used by customers or end-users.
• Make the software accessible to users, verifying they can start using it as expected.
• Verify the deployment goes smoothly and fix any issues that come up quickly

6. Feedback

This is the last step of the Agile Model. In this, the team receives feedback about the product and works on correcting bugs based on feedback provided by the customer.

• Take feedback from customers, users, and stakeholders after each iteration.
• Understand how well the product meets user needs and identify areas for improvement.
• Check for bugs or issues that need fixing.
• Make adjustments to the development plan based on feedback to improve the product further.

Agile SDLC Methods

Some of the Agile Testing Methodologies are:

1. Test-Driven Development (TDD): TDD is the software development process relying on creating unit test cases before developing the actual code of the software. It is an iterative approach that combines 3 operations, programming, creation of unit tests, and refactoring.
2. Behavior Driven Development (BDD): BDD is agile software testing that aims to document and develop the application around the user behavior a user expects to experience when interacting with the application. It encourages collaboration among the developer, quality experts, and customer representatives.
3. Exploratory Testing: In exploratory testing, the tester has the freedom to explore the code and create effective and efficient software. It helps to discover the unknown risks and explore each aspect of the software functionality. 
4. Acceptance Test-Driven Development (ATDD): ATDD is a collaborative process where customer representatives, developers, and testers come together to discuss the requirements, and potential pitfalls and thus reduce the chance of errors before coding begins. 
5. Extreme Programming (XP): Extreme programming is a customer-oriented methodology that helps to deliver a good quality product that meets customer expectations and requirements.
6. Session-Based Testing: It is a structured and time-based approach that involves the progress of exploratory testing in multiple sessions. This involves uninterrupted testing sessions that are time-boxed with a duration varying from 45 to 90 minutes. During the session, the tester creates a document called a charter document that includes various information about their testing.
7. Dynamic Software Development Method (DSDM): DSDM is an agile project delivery framework that provides a framework for building and maintaining systems. It can be used by users, developers, and testers.
8. Crystal Methodologies: This methodology focuses on people and their interactions when working on the project instead of processes and tools. The suitability of the crystal method depends on three dimensions, team size, criticality, and priority of the project.

Principles of the Agile Model

There are 12 Agile Principles mentioned in the Agile Manifesto. Agile principles are guidelines for flexible and efficient software development. 

1. Our highest priority is to satisfy the client through early and continuous delivery of valuable computer software.
2. Welcome dynamic necessities, even late in development. Agile Processes harness modification for the customer’s competitive advantage.
3. Deliver operating computer software often, from a pair of weeks to a couple of months, with a preference to the shorter timescale.
4. Business individuals and developers should work along daily throughout the project.
5. The build comes around actuated people. offer them the setting and support they have, and trust them to urge the task done.
6. the foremost economical and effective methodology of conveyancing info to and among a development team is face-to-face speech.
7. Working with computer software is the primary life of progress.
8. Agile processes promote property development. The sponsors, developers, and users will be able to maintain a relentless pace indefinitely.
9. Continuous attention to technical excellence and smart style enhances nimbleness.
10. Simplicity—the art of maximizing the number of work not done—is essential.
11. the most effective architectures, necessities, and styles emerge from self–organizing groups.
12. At regular intervals, the team reflects on a way to become simpler, then tunes and adjusts its behavior consequently.

Characteristics of the Agile Process

The Agile process is all about being flexible, working together, and focusing on delivering real value to customers. Here is the Characteristics of the Agile Process:

• Agile processes must be adaptable to technical and environmental changes. That means if any technological changes occur, then the agile process must accommodate them.
• The development of agile processes must be incremental. That means, in each development, the increment should contain some functionality that can be tested and verified by the customer.
• The customer feedback must be used to create the next increment of the process.
• The software increment must be delivered in a short span of time.
• It must be iterative so that each increment can be evaluated regularly.

When To Use the Agile Model?

The Agile model works really well for certain types of projects. Here’s when Use the Agile Model:

• When new changes need to be implemented. The freedom that playfulness gives for change is very important.
• New changes can be implemented at a very low cost due to the frequency of new increments.
• Implementing a new feature requires developers to lose only a few days or even just hours of work to get it back and implemented.
• In the Agile model, unlike the Waterfall model, very limited planning is required to start a project.
• Agile believes that the needs of end users are always changing in the dynamic business and IT world.
• Changes can be discussed and features can be redesigned or removed based on feedback.

Advantages of the Agile Model

• Working through Pair programming produces well-written compact programs which have fewer errors as compared to programmers working alone.
• It reduces the total development time of the whole project.
• Agile development emphasizes face-to-face communication among team members, leading to better collaboration and understanding of project goals.
• Customer representatives get the idea of updated software products after each iteration. So, it is easy for him to change any requirement if needed.
• Agile development puts the customer at the center of the development process, ensuring that the end product meets their needs.

Disadvantages of the Agile Model

• The lack of formal documents creates confusion and important decisions taken during different phases can be misinterpreted at any time by different team members.
• It is not suitable for handling complex dependencies.
• The agile model depends highly on customer interactions so if the customer is not clear, then the development team can be driven in the wrong direction.
• Agile development models often involve working in short sprints, which can make it difficult to plan and forecast project timelines and deliverables. This can lead to delays in the project and can make it difficult to accurately estimate the costs and resources needed for the project.
• Agile development models require a high degree of expertise from team members, as they need to be able to adapt to changing requirements and work in an iterative environment. This can be challenging for teams that are not experienced in agile development practices and can lead to delays and difficulties in the project.
• Due to the absence of proper documentation, when the project completes and the developers are assigned to another project, maintenance of the developed project can become a problem.

Conclusion

Agile development Model is more focused on the Flexibility, Teamwork for the improvisation of product and meet the requirement of the customers easily. Agile is really helpful for project which is need to be fast development and skilled team. If you want to learn How the Agile Development Works? Do refer “Agile Methodology Tutorial“

• Agile Software Development Methodology | Framework, Principles, and Benefits