The classic and conventional waterfall model is not ideal in an environment where the project requires constant modifications in the requirements. It delivers the end result or the final product at the end of the entire software development process . As a result, there is no chance for customers to provide feedback during development and propose changes in the existing requirements or add new ones.
Wouldn’t it be more pleasing to get the software product in small chunks and in the early stages of development? This means, wouldn’t it be amazing if you receive the software product in different versions, with every version incorporating new features? This is all possible with the help of the iterative model.
Like the traditional waterfall model, this model does not require the specification of the whole requirements at the beginning of the development. Instead, it starts building the product even with minimum requirements at hand. More interestingly, it is adaptable to the changing needs of customers or end users.
So, let us gain more insights into the iterative model.
This blog post intends to make you familiar with the iterative model in SDLC , along with its features, phases, benefits, and drawbacks.
What is an Iterative Model in SDLC?
It is a flexible SDLC approach that starts the software development process with a few clear and well-defined basic requirements in hand. It does not depend on the entire specification of requirements.
Initially, it takes a set of initial software requirements, implements it, and releases the first version of the software product, which is the first iteration. In the following iteration, this model takes another set of requirements and adds it to the basic version of the software product, which results in the subsequent version. The process continues in iterations until the final product is ready for deployment.
As a result, we can say that every iteration of a process yields a new version of the software product. So, if the customers require changes in any version of the software product, this model implements those changes in its subsequent version.
In a nutshell, we can define an iterative model as an SDLC approach that starts with implementing a small set of requirements and iteratively produces the evolving versions of the software product until it is fully implemented or ready to deploy.
The primary purpose of this model is to identify design and various other practical issues in the beginning phases of development. This, in turn, assists the development team in addressing those issues within the limited budget. If design issues are found in the later development phases, the cost required to fix them would be hefty.
Here are some remarkable features of the iterative model:
- This model is cyclic in nature because, after the requirements planning phase, many other phases get repeated. After every cycle, there is some scope for the software product to improve.
- It supports changes in the requirements at any stage of development.
- It works on constantly improving the software product.
- The continuous improvements of the software product result in lower possibilities of risks.
- The software product’s functionality increases incrementally.
When to Use?
Many times, companies come across circumstances where they do not have the complete set of features and are equipped with only the initial or fundamental software requirements.
Moreover, some companies prefer not to provide the entire project requirements to the development team in one go. Instead, they release the set of requirements periodically or upon the client’s requests for new as well as modifications in existing requirements. In such scenarios, the iterative model comes in handy.
Phases of the Iterative Model
The waterfall model is not adaptable to changing customer requirements, and hence, it is pretty challenging to develop applications using this approach. However, the iterative model overcomes this issue of the waterfall model.
It is analogous to the waterfall model, but the only difference is that it is adaptable to changing requirements of customers. It boosts the efficiency of software development by allowing customers to provide feedback on software releases.
Let us now understand how the iterative model works by looking at the phases involved in it.
1. Requirements Gathering and Analysis
The first stage involves collecting software requirements from customers or end users. Next, it entails analyzing those requirements to determine whether they fit in the pre-determined budget. Besides, this phase also requires the development team to map and evaluate all the business requirements and system information (hardware and software) for their feasibility.
After collecting and analyzing requirements, the development team moves on to designing the software product. For this purpose, they refer to various diagrams, including the state transition diagram, activity diagram, class diagram, and data-flow diagram. The greater size of the project, the higher the complexity of the design for that project.
Once the software design is completed, various developers in a team analyze it and come up with their solutions or strategies. After analyzing all the solutions, the team decides upon a single yet most efficient approach to build the software product.
The core phase of software development is implementation or coding. The development team works on implementing the requirements and the design plan made in their earlier phases. They leverage the organization’s pre-determined coding standards and guides for implementing the software product.
Furthermore, this phase also involves unit testing . After the development team codes each software module, they test that module individually to check for its correctness.
The foremost goal of this phase is to produce a fully-functional version of the software product in that iteration.
The next is the testing phase, which requires the current software build to undergo testing to ensure that it meets certain sets of standards and norms and to uncover some potential errors or bugs. The software build of the current iteration has to undergo different types of software testing , such as performance testing, stress testing, usability testing, and many more.
If there are any errors, the testing team reports them to the development team. After fixing errors, the development sends back the code to the testing team to check its correctness. This process continues until the current software build is completely free from bugs.
In the final stage, the evaluation or review stage, stakeholders, the development team, and various other teams involved in the project evaluate the software build thoroughly. They validate the build to check if it is in compliance with the requirements and yields the expected outcome. They provide feedback related to different aspects of the software product and propose new features.
Additionally, this phase entails the creation of a new requirements plan that the development team needs to implement in the next iteration of the process.
Benefits and Drawbacks of the Iterative Model
Before employing any SDLC approach, it is better to have an in-depth understanding of its pros and cons. Now, we shall discuss some remarkable benefits and major drawbacks of this model.
The primary benefit of this model is that it yields a working model of a software at the very early stages of development. This, in turn, helps the project team to identify and fix design and functional issues in the early phases and saves the expenses of resolving them later.
Some other advantages of this model are as follows:
- This model supports parallel development.
- It is flexible as it lets you easily change any requirements with minimal cost.
- It provides results periodically, right from the early development phases.
- This model is adaptable to the client’s or stakeholder’s requirements.
- In every iteration, the project team identifies and fixes errors, which makes it easy to manage the iteration.
- It helps in managing potential risks involved in the project.
- It is a perfect model for large software products.
- Each iteration produces an operation build.
Though the iterative model offers a number of advantages, it does have flaws too. This model’s main drawback is that it is suitable only for large projects. The reason is that it becomes pretty tough to split small projects into smaller increments or modules.
Here are some other drawbacks of the iterative model:
- It is a resource-intensive process.
- It requires a very high degree of management.
- As the complete set of requirements is not available beforehand, there are chances for the rise of system architecture and design flaws.
- The fact that the ultimate output is unknown at the beginning might be a risk.
- The risk analysis requires highly proficient and skilled resources.
- It is challenging and complex to manage the entire process.
An iterative model is a flexible approach to producing software products whose requirements often change. Except for the requirements gathering and analysis phase, this approach involves the repetition of all other development phases. This makes it possible to incorporate new requirements or change the existing requirements without any hassle. Also, this model makes it easy to spot potential design errors in the early phases.
So, in short, this model is a perfect solution for developing large projects within a minimal budget.
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