Towards a diamond SOA operational model

The triangular operational model with the three roles of service-registry, -provider, and -consumer has been the traditional operational model in Service-oriented Architectures (SOA). The central component in this model, the service registry, plays a passive role. This passive role is due to the lack of adequate information resources. For example, service descriptions provided by service providers are in general not rich enough for service discovery and selection. More elaborate service descriptions are vital in several aspects in Service-oriented Computing (SOC), such as service quality assessment, service discovery and selection, etc. To increase the usability of web services with poor descriptions, we propose a novel approach to extend the traditional SOA operational model by introducing a Diamond model with a new role: the Service Invocation Proxy (SIP). The main goal of this role is to enable service brokers (registries) to play an active role, e.g., to enrich service descriptions with metadata about invocation statistics, service quality measures, and service usage contexts. A SIP plays its role during service invocation where it mediates between consumers and providers at runtime. We have implemented a proof-of-concept of this approach and show the details in the paper.