April 16, 2010

What is the difference between Functional Requirement and Non – Functional Requirement?

The Functional Requirement specifies how the system or application SHOULD DO where in Non – Functional Requirement it specifies how the system or application SHOULD BE.

Some Functional Requirements are,
Authentication
Business Rules
Historical Data
Legal and Regulatory Requirements
External Interfaces

Some Non Functional Requirements are,
Performance
Reliability
Security
Recovery
Data Integrity
Usability

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2 Comments:

Blogger Leif Ashley said...

I began thinking about this in terms of agile and XP. Functional testing is testing the core areas of the application to see if a user function will work as expected. It is not input/output testing. That is unit level testing where junit and other unit testing frameworks play.

Non-functional testing in terms of agile really do not exist, and I would also say they shouldn't exist anywhere else. All the functional categories listed are dependent on the function of the system. So are they really non-functional in nature?

If you're trying to break down the validation of testing, I guess you could do it this way, but I'm not sure the end user (business owner) cares.

8:14 PM  
Blogger lakshmi said...

its nice and useful

9:46 PM  

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