Evolutionary Model in Software Engineering
The Evolutionary Model in software engineering focuses on delivering a partially developed system to users early, rather than waiting until the complete product is ready. This approach starts with a core module and improves the product through iterative and incremental enhancements, guided by continuous feedback.
Instead of developing a large system all at once, the project is broken into smaller, manageable chunks. These smaller modules are prioritized, developed, and delivered one at a time—allowing users to work with early versions while improvements continue in the background.
This makes the evolutionary model especially effective for large-scale projects, where feedback can be gathered throughout the process, and customers can benefit from base features well before the final release.
What is the Evolutionary Model?
Also known as the successive versions or incremental model, the evolutionary model combines aspects of iterative development and incremental delivery in the Software Development Life Cycle (SDLC).
The key idea is to:
- Develop a basic skeleton of the software.
- Add new features in successive versions based on feedback.
- Refine capabilities over time until the product is complete.
Key Characteristics
- Often built using an iterative waterfall approach.
- Includes three main types: Iterative Model, Incremental Model, and Spiral Model.
- Requires initial planning and basic architecture before development.
- Each release includes new functionalities and improvements to existing features.
- Allows changing requirements mid-development.
- Encourages ongoing customer feedback and adaptation.
Types of Evolutionary Models
1. Prototyping Model
A prototype is an early version of the software created to clarify requirements and test ideas.
Phases:
- Communication – Developer and client discuss objectives.
- Quick Design – Focus on visible aspects (UI, inputs/outputs).
- Modeling – The concept is shaped into a basic working model.
- Prototype Construction – A working demo is developed.
- Deployment & Feedback – The prototype is refined until the client is satisfied.
- No need for fully detailed requirements upfront.
- Encourages active user involvement.
- Detects errors and missing functions early.
Disadvantages:
- High client involvement can slow progress.
- Frequent changes disrupt workflow.
- May require rebuilding if the prototype confuses users.
2. Spiral Model
A risk-driven approach combining waterfall and prototyping.
- Development progresses in loops (spirals), with each loop including planning, risk analysis, engineering, and evaluation.
- Suitable for large, high-risk projects.
Advantages:
- Reduces risk through early identification.
- Strong documentation and control.
- Can shorten production time for complex projects.
Disadvantages:
- Costly to implement.
- Not suitable for small projects.
3. Concurrent Development Model
In this model, multiple activities happen in parallel.
- A module can move between states like under development → awaiting changes → completed.
- Useful when changes are frequent and different teams handle different parts.
Advantages:
- Works for all project sizes.
- Provides instant feedback after testing.
- Gives a real-time view of project status.
Disadvantages:
- Requires excellent communication.
- Teams must track multiple activity states.
Comparisons with Other Models
Evolutionary vs Incremental Model
Evolutionary vs Iterative Model
Evolutionary vs Classical Waterfall Model
Evolutionary vs Spiral Model
Advantages of the Evolutionary Model
- Users can test partially developed software early.
- Core modules are tested early, reducing errors in the final product.
- Suitable for large projects with unique features.
- Allows changes based on customer feedback.
- Resources can be allocated gradually.
Disadvantages of the Evolutionary Model
- Difficult to divide into acceptable functional units.
- Final delivery may be delayed.
- High risk of scope creep due to changing requirements.
- Requires constant communication and feedback loops.
