The incremental development model is a prescriptive model which delivers the working component at each increment of the project. Incremental model is implemented when the client needs an immediate release of the project.
In this section, we will discuss the characteristics of the incremental model in brief, along with its phases. We will also consider the scenario when the incremental model can be used. Further, we will discuss the types, advantages and disadvantages of an incremental model.
Content: Incremental Development Model
- What is Incremental Model?
- Phases of Incremental Model
- When to Use Incremental Model?
- Types of Incremental Model
- Advantages & Disadvantages
- Key Takeaways
What is Incremental Development Model?
Incremental model is a process model used by developers to develop software. The incremental model produces a working product (in parts) at each increment. Receiving early delivery of the operational product (in parts) boosts the morale of customer that his requirements are being satisfied. And soon the complete working system will be delivered to him.
The incremental model suggests that the delivered early increments should possess the functionality of customer’s interest and let the rest of the software to be delivered in a period. Let us understand the incremental model with the help of a scenario.
Consider, we have to deliver a word processor to the customer and customers want the delivery of his product by a date that seems to be impossible. So, in the first release, the delivered increment possess file management, document production, editing like functionalities.
In the next release or increment, the delivered functionality would include sophisticated editing tools, advanced file creation capabilities. The further increment would produce features like spell check, grammar checking, mailing, and so on.
So in this way, the incremental model delivers the project in parts. The initial increment is the stripped-down version of the complete system. This stripped-down version helps the customer to evaluate the released increment and suggest modifications which can be implemented in later increments.
The final product has more chances of being accurate and reassures all the requirements of the customer. The incremental model incorporates both linear and parallel process flow as you can observe in the image above.
Phases of Incremental Model
Any iteration of the increment model can use prototyping model for the process flow. Well, the general phases that all the increments have to process are as follow:
1. Requirement Analysis
During this phase, the developers communicate with the customer and note down all the requirements of the customer.
Analyzing the requirements specified by the customer outline of the product is designed using UML diagrams which helps in the implementation of the product.
Programs are coded in small units to implement the operational product. These small units are integrated to achieve the operation product.
When to Use Incremental Development Model?
The incremental model should be used when the deadline fixed for the completion of the project seems to be impossible. There can be many reasons for this scenario like it may be the case that there is a lack of staff for completing the project. So, the company can plan early increments with fewer team members.
It would also be the case that the delivery date of the new hardware required to implement the system is uncertain. So, the developer team can plan early iterations in such a way that the use of the latest hardware can be ignored.
Types of Incremental Model
In this section, we will discuss four approaches to implement the incremental model.
1. Top Down
In the top-down approach, the topmost component of the software is implemented first. Like, the topmost component of any software is the user interface of that software and it is also the visible part of the software.
The user interface can be demonstrated to the client as it imitates the final product. The top-down approach works in-breath first fashion.
In the bottom-up approach, the lowest component of the software is implemented first. The lowest component is the component on which everything is dependent. These components can be classes that can be shared or reused to form a common library for an application.
Here, the customer cannot view the working model in early increments which is the drawback of the bottom-up approach.
3. Middle Out
In the middle out approach, a central component is chosen to implement first. Here, the system start gets developing from the centre. The middle-out method is used for significant software. The components are divided among the developers and are developed concurrently and independently. At last, all the component are merged to form the final software.
4. Use Case-based
In this approach initially, developers analyze the functions that will be required to carry out the task. Then each function is implemented and demonstrated to the client, and depending on the feedback, the function is modified.
This is repeated until the user is satisfied with the function. Then the next function is chosen; it is implemented and demonstrated to the user. In this way, the entire system is implemented. The use case approach works in a depth-first fashion. Here, the client is served immediately with visible products.
Advantages & Disadvantages
Advantages of Incremental Model
- As the components are incorporated one by one, the user has the chance to change the requirements.
- There is early delivery of visible products.
- The client has the satisfaction that the entire product will be delivered soon.
- The client can decide which module should be implemented next.
- Early increments are delivered faster.
Disadvantages of Incremental Model
- The incremental model needs proper planning else; it would delay the delivery of the product.
- Changing requirements of users may arise the cost of the product.
- The incremental model delivers a working component at each increment.
- The first product of the incremental model is generally the core product, and the supplementary features of the product are delivered in further increments.
- The incremental model should be used when the delivery of the entire working product at the committed date seems to be impossible.
- As the supplementary features are delivered in further increments, there is an opportunity for customers to change their requirements.
- The incremental model has four types that include a top-down approach, bottom-up approach, middle-out approach and use case approach.
- The incremental model provides operational and visible product at the early increments.
- As components of the whole product are incorporated one by one, bug detection becomes easier.
So, this is all about the incremental model, it delivers the core component of the entire product in its initial increment, and the supplementary features are delivered in further increments.