are used by applications and GOSA services. These middleware services may implement admin- istrative functions, such as monitoring or managing the usage of GSOA services. Hence, the middleware services are similar to service enablers. Architectures that can be generalized by the GSOA occur in various networks, including the telco, Internet, and IT-based enterprise. For example, IT-using enter- prises implement the GSOA as a Web services SOA with an Internet-based trans- port. In the telco domain, the GSOA is also implemented using the Web services SOA. This is evident in the Parlay X standard that uses Web services to expose sim- ple telco capabilities to external third parties. However, the telco also implements Service Delivery Platforms the GSOA closer to the network. For instance, a GSOA may be implemented using the Parlay standard with CORBA [17] technology. Parlay provides rich logic required to support Parlay X Web services and abstract underlying network functions. An advantage of using the GSOA is that it represents a generic design pattern used in structuring other types of architectures [4]. For example, GSOA may be used to model service platform architectures that abstract network complexities, expose functions to third parties, and deliver abundant services to various customers. Thus, the GSOA may be used to structure the SDP in a technology, implementation, and distribution neutral manner. 2.5 Service Delivery Platform Framework We show a general representation of our SDP framework in Figure 2.4. The figure expresses the layers and domains that provide the foundation of our SDP frame- work. Layers and domains represent design patterns used to structure the framework independently of technologies. Layers group hierarchies of service enablers, while domains distribute layers and their service enablers across various infrastructure Service End-user subscriber Service platform Enterprise Simple applications Simple service enablers (Intermediate applications) Intermediate service enablers (Complex applic