SDLC- Agile Model

Agile software development is based on an incremental, iterative approach. Instead of in-depth planning at the beginning of the project, Agile methodologies are open to changing requirements over time and encourages constant feedback from the end users. Cross-functional teams work on iterations of a product over a period of time, and this work is organized into a backlog that is prioritized based on business or customer value. The goal of each iteration is to produce a working product.

Agile model is a type of Incremental model points on adaptability process and customer satisfaction by quick delivery of product to the customer. In this model the application is divided into small incremental builds and these builds are given in iterations. Each iteration time duration is about one to three weeks. The iteration contains cross functional teams working parallel on many areas such as requirements analysis, planning, design, coding, unit testing, and UAT. A working product is displayed to the customer at the end of the iteration. Customer is actively involved because after every sprint there will be UAT (User Acceptance Testing).

Agile Model Diagrams:

Diagram 1:

 Diagram 2:

• Kickoff: It is a meeting done at beginning stage of the project.
• Scrum Master: Team lead who is responsible for product development. Scrum master explains the requirement to the team and team identifies their task
• Sprint: It is a time taken to develop certain set of requirement is called sprint.

 When to use:

• Whenever customer new changes are needed to be implemented
• Whenever customer need the project very early
• When there is complex project

 Advantages of Agile model:

• Develops the product at very high speed
• Quality of product can be delivered due to frequent customer interaction
• More clarity in requirement
• Less communication gap between team members
• Regular adaptation to changing circumstances.
• Requirement changes are allowed
• Daily support between business team and developers.

 Disadvantages:

• Very tight schedule for team members
• If two/more members are off, then it will lead to project failure
• The project can take off track if the customer is not clear about his requirement / outcome.
• It needs only experienced resources

Agile versus Waterfall Method

Agile and Waterfall model are two different methods for software development process. Though they are different in their approach, both methods are useful at times, depending on the requirement and the type of the project.

Agile Model	Waterfall Model
Agile method proposes incremental and iterative approach to software design	Development of the software flows sequentially from start point to end point.
The agile process is broken into individual models that designers work on	The design process is not broken into an individual models
The customer has early and frequent opportunities to look at the product and make decision and changes to the project	The customer can only see the product at the end of the project
Agile model is considered unstructured compared to the waterfall model	Waterfall model are more secure because they are so plan oriented
Small projects can be implemented very quickly. For large projects, it is difficult to estimate the development time.	All sorts of project can be estimated and completed.
Error can be fixed in the middle of the project.	Only at the end, the whole product is tested. If the requirement error is found or any changes have to be made, the project has to start from the beginning
Development process is iterative, and the project is executed in short (2-4) weeks iterations. Planning is very less.	The development process is phased, and the phase is much bigger than iteration. Every phase ends with the detailed description of the next phase.
Documentation attends less priority than software development	Documentation is a top priority and can even use for training staff and upgrade the software with another team
Every iteration has its own testing phase. It allows implementing regression testing every time new functions or logic are released.	Only after the development phase, the testing phase is executed because separate parts are not fully functional.
In agile testing when an iteration end, shippable features of the product is delivered to the customer. New features are usable right after shipment. It is useful when you have good contact with customers.	All features developed are delivered at once after the long implementation phase.
Testers and developers work together	Testers work separately from developers
At the end of every sprint, user acceptance is performed	User acceptance is performed at the end of the project.
It requires close communication with developers and together analyse requirements and planning	Developer does not involve in requirement and planning process. Usually, time delays between tests and coding