In this era of Cloud Computing and Service Architecture, it is expected that web services will proliferate the current market and business will expose their web service’s as B2B, C2B, E2E and C2C service componets, many web services offer the similar services, and the clients application will demand more value added services and informative services rather than those offered by single entity ,or isolated web services. Synthesis of Service Semantics with high quality is prominent and in high demand, Internet based applications share webservices and offer services as data pipelines and social computing. The client applications are experiencing cost and quality intensive competition to select service portfolio and create semantics service composition, among numerous possible plans, that satisfy their quality-of-service (QoS) requirements. Typical QoS attributes associated with a semantic fabric services are the consumption cost and time, availability of services, dynamic runtime service execution rate, service and entity reputation, and web trends of service frequency and performance payload support. This paper describes the service composition architecture and webservice composition algorithm based on combinatorial and Poisson distribution. As mathematical and implementation framework of the service algorithm maintains the high standard of service QoS composition in a business portfolio of service category and assists the business entity and client application to have better service selection and QoS of request and response.