The World Wide Web has evolved from being a pure
information repository to a more functional and service oriented
platform using technologies such as Web Services. Web service
has been widely employed in e-business, e-government,
automotive systems, multimedia services, process control,
finance, and a lot of other domains. Quality-of-Service (QoS) is
usually employed for describing the non-functional
characteristics of Web services and employed as an important
differentiating point of different Web services. With the
prevalence of Web services on the Internet, a thorough
awareness of the Web service QoS is becoming more and more
important. In this article, an overall description of Web Services
QoS requirements is presented.