Most research focuses on the open standards of Web services and semantic Web but pays less attention to semantics based enterprise modeling, and automated service discovery and service composition are difficult. This paper applies architecture driven modeling approach to constructing semantic enterprise model. Business pattern is the main modeling block that is represented as business components and relationships among them. Business component is attached with semantic information, and component relationships are semantically defined, a primary benefit is that they facilitate automated service discovering, composing, and testing. Business patterns are used to guide service composition by which business goal is mapped into Web services, when business goal is changed, the affected scope of the modifications can be determined by means of component relationships.

This letter discusses the performance of a link carrying calls of preemptive priorities. General /spl kappa/-dimensional steady-state balance equations are deduced and the computational complexity of two solution methods are compared through an example of three priorities. The performance of the link is studied through two conventional metrics for blocking probabilities and preempting probabilities. The "peaking" phenomenon of the preempting line discussed can be used in the design of switches and networks. The coincidence of the preempting probability line with the blocking probability line, displayed in the discussion of numerical results, suggests that better metrics for preemptive performance must be found.