The Incremental Process Model is a software development approach in which the system is developed and delivered in small, manageable parts called increments. Each increment adds new functionality to the existing system until the complete product is built.
Incremental Process Model
Software is not delivered all at once. Instead, development is divided into multiple increments, and each increment goes through requirements, design, development, testing, and implementation phases. Every new release improves the previous version.
- Step-by-Step Development: The system is built gradually in small parts.
- Early Working Software: A usable version is delivered early.
- Customer Feedback: Feedback after each increment improves future releases.
- Flexible to Changes: New features can be added in later increments.
- Structured yet Iterative: Combines planning of Waterfall with flexibility of iteration.
Phases of Incremental Model
1. Requirement Analysis
Requirements for the current increment are gathered and clearly defined.
2. Design & Development
The system design is prepared, and new features are developed.
3. Testing
Each increment is tested to ensure new and existing features work correctly.
4. Implementation
The tested increment is delivered and integrated with previous versions.
These steps repeat until the final system is completed.
Types of Incremental Model
The Incremental Model has two main types, each offers different approaches to how software is developed in parts.
Staged Delivery Model
Develops software in a sequence of planned stages, where each stage delivers a functional part of the system. Each release brings the product closer to completion, allowing it to evolve gradually. Working versions are delivered at regular intervals, making progress visible and manageable throughout the development process. The diagram below shows this model :
Parallel Development Model
Divides the system into multiple modules that are developed simultaneously at the same time by different teams. By working on separate components in parallel, the development process becomes faster and more efficient. This approach reduces overall project time and allows teams to focus on specific functionalities concurrently. Given below is the diagram showing the model:
Use Cases of Incremental Process Model
- When the requirements are well-defined and clear
Because increments can be planned and developed step-by-step with minimal requirement changes. - If the project has a long development timeline
Incremental delivery helps manage complexity over time by breaking the project into smaller, manageable parts. - If the customer needs a quick product release
You can deliver the most critical features early in the first increment, allowing the customer to start using the software sooner. - When you want to develop the most important features first
This allows early feedback on key functionalities and better prioritization for subsequent increments.
Note: The Model is not ideal when the software development team is not highly skilled or experienced because managing increments and integrating them well requires a competent team.
Advantages
- Early Software Delivery, improves customer satisfaction
- Easy to Manage Changes between increments
- Better Risk Management through early testing
- Cost Control by spreading budget over stages
- Simpler Debugging due to modular development
- High Software Quality through continuous testing
Disadvantages
- Requires Skilled Team and proper planning
- Cost May Increase due to repeated testing and integration
- Design Issues if future requirements are unclear
- Integration Challenges between increments
- Repeated Bug Fixing across multiple increments