Performance and Systems

Performance is an important aspect of any system. This is an essential characteristic of a system which signifies its behavior under particular usage circumstances. Depending upon the system, KPI to measure performance gets change. From mileage of an automobile engine to the grade of a student is a one or other form of performance KPIs. Performance of a system seriously impacts the usability of that system. Software systems including web applications are no exceptions in this. Hence, this is considered as a major important non functional requirement of any web application.

In web systems engineering, a functional requirement describes what a system must do or specifies what system must be able to do. It can be described as a set of inputs, the behavior, and outputs. Whereas, requirements that specify about the system itself, and how well it performs its functions are often called Non-functional requirements, or 'performance requirements' or 'quality of service requirements.' Examples of such requirements include usability, availability, reliability, scalability, supportability, testability, performance, maintainability, and (if defined in a way that's verifiably measurable and unambiguous) ease-of-use.

From the bunch of Non functional aspects of a system, two important and correlated features are:

•           Performance:   Performance refers to information regarding your application’s response times, throughput, and resource utilization levels. High performing system means low response time, high throughput with minimum resource utilization.
•           Scalability:       Scalability refers to an application’s ability to handle additional workload, without adversely affecting performance, by adding resources such as processor, memory, and storage capacity. For highly scalable system Supported user load is proportional to the Resources available.