---
title: "22-performance-and-security"
aliases: 
tags: 
- info201
- lecture
---

# Performance requirements
- e.g., credit card system
	- functional reqs
		- sales authorised only for valid cards
		- generate monthly statements
		- performance requirements
			- cards are validated quickly
			- statements are accurate and generated on time
		- quickly, accurate, and on time need to be operationalised, measured, and tested.

Why are they important
- vital quality factor
- infosystems are wide and varied
- wide range of performance characteristics

- impact of changing requirements, e.g., adding a new module
- need to consider (often conflicting) organisational priorities
- critical to unambiguously document and agree

Things to consider
- can interact and conflict with each other
	- accuracy vs speed
	- speed vs space
	- often a trade-off or compromise
- selectig best developent techniques for taget system
	- algorithms
	- data structures
	- languages and frameworkds
	- constraints of target platform