What are functional and non-functional requirements?

Requirement definition:

Requirements are the capabilities and conditions that must be met by the system (in a broader sense, the project.

Requirement category:

(1) in general use, the requirements are as follows:Functionality(Behavior) andNon-functional(OthersAll actions.

　　Functional requirementsYes, there are specific requirements for content completion.

For example, such as customer logon, email sending and receiving, and posting and leaving on the Forum website.

　　Non-functional requirementsSoftware products must have features other than functional requirements to meet users' business needs, including system performance, reliability, maintainability, scalability, and adaptability to technology and business.

For example, performance requirements: The system is required to meet the requirements of 100 people at the same time, the page response time cannot exceed 6 seconds;

Reliability: The system can run continuously for 7 × 24 hours, and the annual unplanned downtime cannot exceed 8 hours. Fast deployment is required, especially when the system fails.

(2) In the Unified Process (up),Furps +"Model for classification.

• Functional: features, functions, and security;

• Availability (usability): Human Factors, help, documentation;

• Reliability: Fault frequency, recoverability, and predictability;

• Performance: response time, throughput, accuracy, validity, and resource utilization;

• Supportability: adaptability, maintainability, internationalization, and configurability.

"In" furps +"+"Refers to some auxiliary and secondary factors, such:

• Implementation: resource restrictions, languages and tools, and hardware;

• Interface; constraints imposed on external system interfaces;

• Operation: System Management for its operation settings;

• Packaging, for example, a physical packing box;

• Authorization (legal): License orOthersMethod.

The use of the "furps +" Classification Scheme (or other classification scheme) as a list of checks for the scope of requirements is effective, and some important aspects of the system can be avoided.

Some of these requirements can be collectively referred to as quality attribute, quality requirement, or "an attribute" of the system ". These requirements include availability, reliability, performance, and support.