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Table of contents
1.
Introduction
2.
Agile Model
3.
Working of Agile Model
4.
Principles
5.
Phases
6.
Agile Methodologies
6.1.
Rational Unified Process (RUP)
6.2.
Crystal Clear
6.3.
Scrum
6.4.
eXtreme Programming(XP)
6.5.
Feature Driven Development(FDD)
6.6.
Lean Software Development
6.7.
Adaptive Software Development(ASD)
6.8.
Dynamic Systems Development Method(DSDM) 
7.
Characteristics of the Agile Process
8.
Agile Vs Traditional SDLC Models
9.
When To Use the Agile Model?
10.
Advantages
11.
Disadvantages
12.
How to Implement an Agile SDLC Model?
13.
FAQs
14.
Key Takeaways
Last Updated: Apr 15, 2024

Agile Model

Author Hari Sapna Nair
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Introduction

Software Development Life Cycle (SDLC) is used in software industries to develop, design, and test high-quality software. It aims to produce software that meets customer expectations reaches completion within times and cost estimates.

SDLC consists of a well-elaborated plan describing developing, maintaining, altering, or enhancing specific software. Various SDLC models are defined and designed, followed during the software development process. These models are called the Software Development Process Models. Some of these models are the Agile  model, waterfall model, iterative model, etc.

This article will extensively discuss one of the SDLC models, the agile model, its principles, working,  advantages, disadvantages, phases, agile methodologies, etc. 

Recommended Topic,  human computer interaction

Agile Model

The agile methodology is a type of iterative approach to software development. The agile methods break tasks into smaller iterations or parts that do not directly involve long-term planning. The project requirements are listed down when the development process begins. Plans regarding the duration, the number of iterations, and the scope of each iteration are defined well in advance.

The Agile model aims to facilitate quick completion of the project completion. The agility required to complete the tasks is achieved by removing activities that may not be essential for a specific project, fitting the process to the project, etc. 

Each iteration is considered a short time "frame" in the Agile process model, typically lasting 1 to 4 weeks. The project is divided into various smaller parts to minimize the project risk and reduce delivery time. Each iteration involves a team of developers working through a complete SDLC, including planning, design, coding, requirements analysis, and testing before a working software product is demonstrated to the client. After every iteration, a working software product is displayed to the customer and stakeholders.

 

Source: https://www.tutorialandexample.com/agile-model-in-software-engineering

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Working of Agile Model

Each project needs to be addressed differently in the agile model to meet project requirements, and current methods must be changed. In the agile model, tasks are divided into short time frames to provide specific features for the release.

An iterative approach is taken here, and the working software versions are delivered after each iteration. Each iteration is incremental in terms of the features, and the final version of the software will contain all the features requested by the client. The main principle of the agile model is the delivery of an increment to the customer after each time box. 

Principles

The principles of the agile model are as follows:-

  • Establish a close connection with the customer during development and gain a clear understanding of various requirements. At the of every iteration, the customer representative and the stakeholders review the progress made and re-evaluate the requirements.
  • It relies on working software deployment rather than proper documentation.
  • Incremental software versions are frequently delivered to the customer representative.
  • Requirement change requests from the customer are possible and efficiently incorporated.
  • It emphasizes that having efficient team members and enhancing communication are more critical. It is realized that communication among the developers can be achieved only through face-to-face communication and not through the exchange of formal documents.
  • It recommends that the development team size be kept small to help the team members meaningfully engage in communication and have a collaborative work environment.

Also read,  V Model in Software Engineering

Phases

The agile model is the combination of incremental and iterative process models. The steps involved in the agile model are as follows: 

1. Requirements gathering

We must define the requirements in this phase. The business opportunities and plan the time and effort needed to build the project are explained in this phase. Based on this information, we can evaluate the technical and economic feasibility.

2. Design the requirements

Once we have identified the project, we must work with stakeholders to define requirements. We can use the user flow diagram or the high-level UML(Unified Modeling Language) diagram to show the work of features and show how it will apply to the existing system.

3. Iteration: The work begins when the team defines the requirements. Developers and designers start working on their projects to deploy a working software product. This product will then undergo various stages of improvement.

4. Testing

The Quality Assurance(QA) team examines the product's performance and verifies if any bug is present in the product

5. Deployment

The team issues a working product for the user's work environment.

6. Feedback

After releasing the software product, the last step is feedback. The team receives feedback about the software product and works on the feedback received.

Agile Methodologies

Some popular agile methods include Rational Unified Process, Crystal Clear, Scrum, eXtreme Programming, Feature Driven Development, Lean Software Development, Adaptive Software Development, and Dynamic Systems Development Method. These methods are now collectively known as the Agile Methodologies after the agile manifesto was published in 2001.

Rational Unified Process (RUP)

Rational Unified Process is an agile methodology that splits the project life cycle into four phases. During each phase, the core development disciplines take place: business modeling, requirements, analysis and design, implementation, testing, and deployment. Each phase in RUP has an objective that must be completed before the project can progress to the next phase.

Crystal Clear

Crystal Clear is for projects with a small team. It props a few principles to get a project from a bad zone to a safer zone. It puts more iteration on the people rather than the process and works best when working on non-critical projects. There are three concepts of this methodology:-

1. Chartering: Multi activities are involved in this phase, like forming a development team, developing plans, performing feasibility analysis, etc.

2. Cyclic delivery: This consists of two more cycles:

  • The team updates the release plan.
  • The integrated product is delivered to the users.

3. Wrap up: This phase performs deployment and post-deployment according to the user environment.

Scrum

Scrum is a lightweight, agile framework focusing on time-boxed iterations called sprints. It focuses mainly on managing tasks in team-based development conditions. Three roles are present here, and their responsibilities are as follows:

  • Scrum Master: They are the facilitators of the scrum. They help facilitate scrum to the team by ensuring the scrum framework is followed. They are committed to the scrum practices but are also flexible and open to opportunities for the team to improve their workflow.
  • Product owner: They create the product backlog, prioritize the delay, and distribute functionality on each repetition.
  • Scrum Team: The scrum team manages its work and organizes the work to complete the sprint.

eXtreme Programming(XP)

eXtreme Programming allows small to medium-sized teams to produce high-quality software products and adapt to evolving and changing requirements. This methodology is used when customers are constantly changing demands or requirements or unsure about the software's performance.

eXtreme Programming emphasizes the technical aspects of software development. It is precise about how engineers work as following good engineering practices allows the teams to deliver high-quality code sustainably.

Feature Driven Development(FDD)

Feature Driven Development is customer-centric, incremental, and iterative, intending to deliver tangible software results efficiently. This methodology focuses on "Designing and Building" features. It describes the small steps of the work that should be obtained separately per function.

FDD allows teams to update the project regularly and identify errors faster. Clients can also be provided with information and substantial results at any time. FDD is preferred among development teams because it helps reduce confusion and rework.

Lean Software Development

The lean software development method follows the principle of "just in time production." It indicates the increasing speed of software development and reducing costs. The seven established lean principles come with tactics, practices, and processes that help build more efficient software products. Those principles are as follows:-

  • Eliminating the waste
  • Fast Delivery
  • Amplify Learning
  • Builds Quality
  • Respect Teamwork
  • Delay the commitment
  • Optimizing the whole system

Adaptive Software Development(ASD)

Adaptive Software Development is a direct outgrowth of Rapid Application Development (RAD). It enables teams to quickly and effectively adapt to changing requirements by evolving their products with lightweight planning and continuous learning. It encourages teams to develop according to a three-phase process: speculate, collaborate, and learn.

Dynamic Systems Development Method(DSDM) 

DSDM is a rapid application development strategy that gives an agile project distribution structure. In this methodology, the users must be actively connected, and teams must be given the right to make decisions. The techniques used in DSDM are Time Boxing, Prototyping, and MoSCoW Rules.

The DSDM project contains the following seven stages:

  1. Pre-project
  2. Feasibility Study
  3. Business Study
  4. Functional Model Iteration
  5. Design and build Iteration
  6. Implementation
  7. Post-project

Characteristics of the Agile Process

The Agile process, known for its flexibility and efficiency in software development, is characterized by several key features:

  • Iterative and Incremental Development: Agile focuses on breaking down the project into small, manageable increments or iterations, each delivering functionality.
  • Customer Collaboration: Agile emphasizes close collaboration throughout development, ensuring the product meets their needs and expectations.
  • Adaptability and Flexibility: Agile methodologies allow for rapid adaptation to changes in requirements, technology, or market conditions.
  • Continuous Feedback and Improvement: Regular reviews and retrospectives are integral to Agile, facilitating constant feedback and improvement of both the product and the process.
  • Focus on Individuals and Interactions: Agile prioritizes individuals and interactions over processes and tools, valuing effective team collaboration and communication.
  • Working Software as Primary Measure of Progress: Delivering functional software in each iteration is a key focus, with progress measured in usable features.
  • Sustainable Development Pace: Agile promotes a sustainable development pace, ensuring the team maintains consistent speed and quality over time.
  • Cross-Functional Teams: Agile teams are often cross-functional, encompassing a range of skills and expertise necessary to deliver the product.
  • Self-Organization and Empowerment: Teams in Agile are self-organizing and empowered to make decisions, leading to increased accountability and innovation.
  • Simplicity and Efficiency: Agile stresses the importance of clarity and efficiency in development, focusing on what is necessary to deliver value.

Agile Vs Traditional SDLC Models

Agile and Traditional models are two very different approaches to software development with distinct advantages and disadvantages. Both models have different applications and follow different methodologies. Let's first understand what traditional SDLC models are.  

Traditional SDLC models are best suited for projects with well-defined requirements and consist of several phases, such as planning, design, implementation, testing, and maintenance. Each stage must be completed before starting the next one. For example - the waterfall model. Let us compare the two models to understand their differences better.

Traditional SDLC Model

Agile Model

The traditional SDLC model is a linear and sequential approach to software development.

The agile model is an iterative and flexible approach to software development. 

It doesn't provide a clear plan to incorporate changing requirements, which can lead to delays.  

It focuses on the working software, feedback, and adapting to new requirements.  

It focuses on a structured plan, not the final product's delivery.    

The Agile model aims to deliver the product quickly.  

It focuses on documentation, which helps track the progress and decisions made throughout the project.

The Agile model lacks documentation. 

It includes regular meetings, also known as sprint meetings, to track the development team's progress.

It is best suited for projects that require a structured approach and have well-defined requirements.

It is best suited for projects that require rapid development and have changing requirements based on user feedback.  

The actual cost of the project can be more than the expected cost.      

The actual and expected costs of the project are the same, as there is no scope for delay in the delivery of the final product. 

When To Use the Agile Model?

The Agile model is best suited for scenarios where flexibility, customer collaboration, and rapid response to change are crucial. It's particularly effective in the following situations:

 

  • Dynamic Requirements: When project requirements are expected to change frequently due to evolving market trends, customer needs, or technological advancements.
  • Customer Involvement: Projects that benefit from continuous customer feedback and involvement, ensuring the final product aligns closely with client expectations.
  • Complex Projects: Agile allows for gradual discovery and adaptation in complex projects where not all requirements are known upfront.
  • Rapid Delivery: When the priority is to deliver a working product quickly and make iterative improvements over time.
  • Innovation and Experimentation: Agile is ideal for projects requiring innovation and experimentation, as it accommodates evolving solutions.
  • Collaborative Work Environments: Projects that thrive on team collaboration and communication benefit from Agile's emphasis on team dynamics.
  • Software Development: Particularly in software development, where Agile can effectively handle the frequent updates and changes in technology.
  • Risk Management: Agile helps in early identification and mitigation of risks, as regular reviews and iterations expose potential issues early on.
  • Small to Medium-Sized Teams: Agile works well with small to medium-sized teams that can manage self-organization and rapid decision-making.

Advantages

The agile method has the following advantages:-

  • It reduces the overall development time of the project.
  • Produce well-written compact programs with fewer errors.
  • Customer representatives get the idea of an updated software product after every iteration. So, it is easy for them to change any requirement if necessary.
  • Efficient design fulfilling the business requirement is produced.
  • It is a realistic approach to software development.
  • It promotes cross-training and teamwork.
  • Functionalities can be developed rapidly and demonstrated.
  • Suitable for fixed as well as changing requirements
  • It is capable of delivering early partial working products.
  • It provides flexibility to the developers.

Disadvantages

The agile method has the following disadvantages:-

  • Lack of formal documents creates confusion, and critical decisions taken during various phases can be misinterpreted at any time by various team members.
  • Maintenance of the developed project can become complicated when the project is completed and the developers are assigned to another project due to a lack of proper documentation.
  • Difficult to handle complex dependencies.
  • Risk of sustainability, extensibility, and maintainability.
  • Strict delivery management dictates the scope, functionality to be delivered, and adjustments to meet the deadlines.
  • They create the product backlog, prioritize the delay, and distribute functionality on each repetition


Also check out - Phases of Compiler

How to Implement an Agile SDLC Model?

The agile development approach is a continuous process of improvement. It is essential to be open to change and adapt to these changes as the requirement arises. To meet the needs of the client, we require the right team and the correct methodologies. Let's look at how we can implement an agile SDLC model by following these given steps -

Implementing the Agile Model
  • Assembling the teamThe team should include professionals who will meaningfully contribute to the project. It must be a small team that is strong enough to handle the challenges that come with the project.  
  • Setting project goals and objectivesDirectly working with the client to understand the project's requirements and setting goals and objectives is essential to start the project. This also includes considering user feedback to analyze the features of the software.  
  • Planning and prioritizing backlogPrioritize the user requirements based on their complexity and relevance. This information will be useful while creating the plans for the project.
  • Conducting regular sprintsPlan regular meetings, also known as sprint meetings. During each sprint, the team will work on the user requirements and deliver the final software while incorporating other changes. This shall be completed within the deadlines.    
  • Following the agile methodologiesWe can use Agile methodologies, such as SCRUM and Lean, to manage the development process of the software, make a framework for planning, and implement changes to the project. 
  • Tracking progressMonitor the progress and identify the areas of improvement. Use this data to adapt the project plan according to the user's requirements. 
  • CommunicationEmphasize constant communication between the development team and the client. Plan regular meetings wherein the team reflects on the software's progress and considers the client's needs if they come up with new requirements and features based on user feedback
  • TestingTesting the software after each phase is essential to ensure the delivery of high-quality software within the given time.
  • Continuous ImprovementMake space for continuous improvement by reviewing feedback and exploring new tools and techniques throughout the project. 

FAQs

1. When should we use the agile model?

Ans:- The agile model can be used in the following scenarios:-

  • When there is a need to make frequent changes.
  • When the project size isn't very large.
  • When there is a team of highly qualified and experienced professionals.

2. What is the difference between the agile model and the traditional SDLC models?

Ans:- The agile model is based on adaptive software development methods. On the other hand, the traditional SDLC models like the waterfall model are based on a predictive approach. These predictive teams usually work with detailed planning and clearly forecast the tasks and features to be delivered during the product life cycle.

3. What type of approach does the agile model use?

Ans:- The agile model uses an adaptive approach, i.e., it has no detailed planning, and future tasks depend on what features need to be developed. There is feature-driven development, and the team dynamically adapts to the changing product requirements. The product is tested very frequently through the various release iterations, minimizing the risk of any significant failures in the future.

The agile model became popular over time because of its flexibility and adaptability.

4. Why did the agile model come into existence?

Ans:- In earlier days, the iterative Waterfall model was used to complete a project. But nowadays, developers face various problems while using it to develop the software. The main difficulties included customer change requests during project development and the high cost and time required to incorporate these changes. To overcome these drawbacks of the Waterfall model, in the mid-1990s, the Agile Software Development model was proposed. 

5. What is a time box in the agile model?

Ans:- The time to complete an iteration is known as a time box. A time box is the maximum time needed to deliver an iteration to customers. The development team can reduce the provided functionality during a time box to deliver it on time. 

Key Takeaways

In this article, we have extensively discussed the agile model, its principles, working,  advantages, disadvantages, phases, agile methodologies, etc. 

Recommended Reading:

We hope that this blog has helped you enhance your knowledge regarding the agile model and if you would like to learn more, check out our articles on Software Engineering. Do upvote our blog to help other ninjas grow. Happy Coding!

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