Significance of non-functional requirements to software systems

In the previous chapter we discussed how the arrangement of Boundary Entities, Domain Entities and Control entities was insufficient wrt the Non- functional requirements of the system.

Significance of Non-functional requirements to software systems

The importance of Non- functional requirements can be understood from the fact that the market success or failure of a system is single handedly decided by how closely the system matches the non functional expectations of its users.

We also know that the Non- functional characteristics of a system are the differentiating factor between multiple products offered by different vendors within a particular product range with nearly similar features and the cost.

I can go to the extent of saying that "Functional requirements of a system are just a prerequisite but the design/architecture and the project implementation plan of the system is greatly influenced by the Non- functional requirements of the system."

We will also understand this statement in detail in the case study where we will be designing a financial portal , wherein by using the minimal functional requirements we will come out with the design of the system just on the basis of the non functional requirements of the system.

Now let's understand the Non-functional requirements in detail.

We will also discuss how Non-functional requirements can single handedly change the design/architecture and the project implementation plan.

Non Functional Requirement

What are Non-functional requirements?

Whenever I pose this question to my participants, I usually get answers like

  • Non Functional Requirements are implicit requirements.
  • Non Functional Requirements are requirements that are never given by the customers directly.
  • Non Functional Requirements are requirements that are not expected by the customer.

Out of these the first two answers may be true but the third one is definitely not true.

As the definition suggests "Every other requirement of the system which the customer expects apart from the functional requirements is called the Non- functional requirements of the system."

So saying that non functional requirements are not expected by the customer is just not true.

 
Hemant Jha
Founder - VPlanSolutions
Researcher, Trainer

www.VPlanSolutions.co.in