An Internet application can invoke several services--a stock-trading Web service, for example, could invoke a payment service, which could then invoke an authentication service. Such a scenario is called a composite Web service, and it can be specified statically or established dynamically. Dynamic composition of Web services requires service consumers to discover service providers that satisfy given functional and nonfunctional requirements including cost and QoS requirements such as performance and availability. In previous columns, I've examined how quality of service (QoS) comes into play for service providers, consumers, and parallel transactions. Here, I'll show how it fits into composite Web services.
[1]
E. Michael Maximilien,et al.
A framework and ontology for dynamic Web services selection
,
2004,
IEEE Internet Computing.
[2]
Daniel A. Menascé.
Response-time analysis of composite Web services
,
2004,
IEEE Internet Computing.
[3]
Daniel A. Menascé,et al.
QoS Issues in Web Services
,
2002,
IEEE Internet Comput..
[4]
Heiko Ludwig,et al.
Web services QoS: external SLAs and internal policies or: how do we deliver what we promise?
,
2003,
Fourth International Conference on Web Information Systems Engineering Workshops, 2003. Proceedings..