ISTQB - Incremental Build Module

We have understood about the waterfall model and V model of Software development. Now we will get detail idea about the incremental model. Here in incremental model, whole requirement will be device in the small group. For example If we want to draw a picture of a man then first we will complete whole face features then we will draw Hands and legs, afterwards we will go for body shape and then in last stage we will finalized whole drawing by making some small changes of shapes and shades. This kind of same steps have been followed in incremental model.

Incremental model will have multiple development cycle and each individual development cycle will follow the Waterfall model so we can say that Multiple Waterfall Cycle is equal to incremental model as whole software development cycle have been divided in very small group of modules which can be managed easily. In incremental model, each development cycle will follow the steps like requirement gathering, Design, Development and Testing. Each module have been divided in the version system and Team will work on the first version on early basis. Each module development have been done incrementally and each upcoming model of the application will add functionality to the previous model.

This process will be performed till all the upcoming model will be completed. We also can take an example of puzzle. To make one picture in the puzzle, we will fix the pieces of the picture one by one and then we will get whole picture on floor, just the way we will get whole project afterwards as one by one model of the project have been fixed or completed incrementally. At the last model, we will combine whole product in one model and this will be delivered to the client. This is all about the Incremental model.

The main characteristics of this model is, we have to divide the system into small parts. This small part can be define as small projects. This small projects should be built with 100% success ratio, otherwise final system will not be delivered perfectly. Whichever the high priority requirements have been noted down, that must be covered first. Once the division of the system have been done this should not be changed often.

Now we will define its advantages and dis advantages.

Advantages of Incremental Model:

1. Project can be developed quickly as compare to waterfall model.
2. If any requirement will be changed then it will be flexible to fix this requirement in between of the software development life cycle.
3. This model is cost effective.
4. Testers can catch more errors and client can be involved in all software development cycle.
5. Debug procedure is easy as it will have small iteration of requirement.

Disadvantages of Incremental Model:

1. It is mandatory to design and organized each level of incremental model.
2. Each level of model will not be overlapped to each other.
3. If one problem have been occurred and resolved in one module then its effect needs to be resolved in each level of application.
4. Some issue may occur due to requirements division. The architecture of this model can be a problem of system management.

When to use Incremental Model:

1. This kind of model can be used for the project or application which does have clear requirements and requirements itself divided in different models. Product will be developed in different phases in Incremental model. For Example, A product will be divided in A1, A2, and A3…An etc. and delivered accordingly.
2. Incremental model have been used to develop a web application or a product based company where all the requirements have been discussed with internal team and as per the convenience all the implementation have been managed.
3. When product launch will be declared soon at that time this model can be used.
4. If resources with lots of skills are not available for same time, this model can be help to start the product with low skills and meanwhile resources can be hired for incremented levels.
5. The risk ratio of this model is high and goal of this model is clear.
6. When a New technology will be implemented in the product, this model will help to grow the product effectively.