Incremental model in software engineering is a one which combines the elements of waterfall model which are then applied in an iterative manner. It basically delivers a series of releases called increments which provide progressively more functionality for the client as each increment is delivered.
In the incremental model of software engineering, waterfall model is repeatedly applied in each increment. The incremental model applies linear sequences in a required pattern as calendar time passes. Each linear sequence produces an increment in the work.
Diagram Of Incremental Model
As from the diagram, you can see that there are 5 phases(tasks) which are carried out in each increment. If you want to see what activity is carried out in each phase, then check out this post: Phases of waterfall model as the phases are same.
The first increment is often a core product where the necessary requirements are addressed, and the extra features are added in the next increments. The core product is used and evaluated by the client. Once the core product is assessed by the customer, there is plan development for the next increment. Thus in every increment, the needs of the customer are kept in mind, and more features and functions are added, and the core product is updated. This process continues till the complete product is produced.
The increments earlier to the main increment are called as “stripped down” versions of the final product. These increases form a base for customer evaluation. On this basis, the client can suggest new requirements if required.
If there are less number of employees to work on the project Incremental development model is very useful to complete the project before the deadline. In a project, early increments can be done with less number of people. In case if the core product is well-defined and understood more employees could be added if needed in the future increments.
One of the benefits of the Incremental process model is that it can be planned to manage technical risks.
Let’s now see the advantages and disadvantages of the incremental model.
Advantages Of Incremental Model
- Initial product delivery is faster.
- Lower initial delivery cost.
- Core product is developed first i.e main functionality is added in the first increment.
- After each iteration, regression testing should be conducted. During this testing, faulty elements of the software can be quickly identified because few changes are made within any single iteration.
- It is generally easier to test and debug than other methods of software development because relatively smaller changes are made during each iteration. This allows for more targeted and rigorous testing of each element within the overall product.
- With each release a new feature is added to the product.
- Customer can respond to feature and review the product.
- Risk of changing requirement is reduced
- Work load is less.
Disadvantages Of Incremental Model
- Requires good analysis.
- Resulting cost may exceed the cost of the organization.
- Each phase of an iteration is rigid and do not overlap each other.
- As additional functionality is added to the product, problems may arise related to system architecture which were not evident in earlier prototypes.
Example of Incremental Model :
As you can see in the above example, the core product is a cricket game where only two important players and one umpire is present in the match. In the next increment fielders are also added in the game, and thus the increases go on with new features being added with every increment.
Incremental Model PPT
This is how the incremental model works. If you have any more doubts or questions, please ask them in comments.
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