This paper presents an architecture to facilitate efficient evaluation and selection of 3rd party web services for service providers. Most service provider architectures have primarily focused on providing web service front ends to legacy systems, aggregating and delivering services via workflows. These architectures primarily considered static business contracts between the service provider and its (web-service enabled) business partners. This approach makes these architectures inflexible to variations in business requirement, partners' performance and customer requirements. Our architecture provides a flexible means for service providers to optimize business performance. Based on the historical performance, extant context, and optimising business rules, the appropriate service is selected and invoked to serve a customer request. We have developed a prototype system ODSS-in-ENDS, that demonstrates this capability.