Doubt about functional or non-functional requirement

Question

I recently started to read a little about functional and non-functional requirements, especially the various classifications that a non-functional requirement can have. However, I still have difficulties on certain occasions to differentiate both.

To be more specific, I am raising requirements for an educational game, in which players can choose a game mode. Basically, the game mode would allow the user to play individually or in a group.

Considering this specific requirement, would it be functional or non-functional? And is there any technique or tip that easily differentiates functional requirements from non-functional?

Answer 1

Functional requirements are the development tasks that will be or need to be developed

• RF001 - Include product
• RF002 - Change product
• RF003 - Consult product
• RF004 - Delete product

Non-functional requirements understand as premises, performance requirements and limitations, example:

• RNF001 - The XML file must not exceed 500kb.

• RNF002 - Sending files must not exceed 60 seconds.

Although there should be a BUSINESS RULE that prevents reaching these borders and limits.

Answer 2

Absolutely correct! It is a feature that needs to be developed that the user is obliged to select the mode.

Let’s look at the case below:

NON-FUNCTIONAL REQUIREMENT:

RNF001 - The XML file must not exceed 500kb. This is a requirement imposed by the electronic invoice webservers.

And if the file is greater than 500k?

The Sefaz will respond to your request normally, although not accept the file and return an error. But you did not need to encode anything. At most, it will return an error message to the user stating that the file was rejected because of its size.

Optionally, you can specify a FUNCTIONAL REQUIREMENT associated with this RNF, which would be something like:

Rfxxx - The application must be able to inform the user that the XML file is near/exceeded the/upload limit. (Someone needs to encode this!)