Evaluation of SDP Conceptual Model

By extending the IN conceptual model concepts to the SDP we have defined a concep- tual viewpoint. This viewpoint defines various abstractions that are structured in the SDP conceptual model. The abstractions contribute to the definition of the SDP framework. We evaluate the SDP conceptual model against the generic concepts extracted from the IN conceptual model. In addition, the evaluation provides answers to the questions posed in Chapter 1 Section 1.3. We also present the comparison between IN and SDP conceptual models in Table 4.1.

The SDP conceptual model identifies external IT-using enterprises that use SDP services to create or enhance applications. These applications provide services to customers. No

IN Conceptual Model SDP Conceptual Model

Plane Description Plane Description

Service customer services described by

integrating service feature de- scriptions. No implementation.

Application customer services are described and im-

plemented by an enterprise. This is ex- ternal to the telco and SDP.

Global Functional

building blocks (SIBs) define reusable service logic. Chains of SIBs implement service fea- ture descriptions and therefore customer services.

Generic Service

application implementations use

generic services via technology inde- pendent interfaces.

Service Component

service components offer an API to ac- cess service related telco network capa- bilities.

Distributed Functional

implement SIBs using dis-

tributed functional entities

that execute functions via

information flows.

Service Function

service functions offer an API to ac- cess telco infrastructure specific capa-

bilities and resources. Also, service

functions implement a communication mechanism to interact and satisfy ser- vice component request.

Physical functional entities map to phys-

ical elements that implement their functions using specific

technologies. Also, specific

protocols implement functional entity information flows.

Infrastructure connected and technology and distribu-

tion specific telco systems provide ser- vice functions with access to their spe- cific functions.

Table 4.1: Comparison of Conceptual Models

business model is defined to accompany the SDP conceptual model, since the conceptual model limits business entities to external application developers.

We use the concept of planes as a design pattern to structure a SDP architecture, that is the SDP conceptual model. The SDP conceptual model uses planes to expose additional SDP details than the proposed SDP architecture, shown in Figure 1.3. Like the IN, the SDP conceptual model planes hide technology and distribution details of their applications or services. As a result, the SDP conceptual model inherits these technology and distribution neutral properties. In the conceptual model service related planes increase the levels of

intelligence in the telco. Also, these service related planes are layered according to their

level abstraction. For example, higher service planes abstract complex intelligence of lower planes, such that simpler access to telco network capabilities is provided to external devel- opers.

The SDP conceptual model’s hierarchy of planes and abundant services increase the sepa-

rationand independence between telco infrastructure and application implementations. For

example, applications using generic services are decoupled from the telco infrastructure. Thus, the telco infrastructure is adequately abstracted by the various levels of SDP services. All SDP services further support this infrastructure independence by providing access to

their functions using implementation independent interfaces. Generic services expose their interfaces to application developers, while using less abstract service component interfaces. Service components use complex interfaces exposed by service functions to access telco infrastructure capabilities. Thus, the SDP conceptual model only exposes generic service interfaces to external IT-using enterprises, since they provide the most abstract access to telco infrastructure capabilities.

Similar to the IN, the SDP must implement its services and planes using standards. By implementing standards further independence of applications and telco infrastructure is gained. As a result, the telco conforms to these standards and ensures infrastructure can support standardised services. Also, developers benefit from standardised services and in- terfaces since they have a constant repository of reusable services for application develop- ment. Also, with standardised services and interfaces interactions between telco and exter- nal IT-using enterprises becomes standard-based. Candidate standards for generic services and their interfaces is Parlay X, while Parlay may implement service components and their interfaces. Also, the IMS [24] may implement a set of service functions, where SIP [37] implements horizontal service function communication. Additional standards may be used to implement remaining service functions and their communications. As a result, service planes may be implemented as distributed platforms that support the implementation of these standards.

Like the IN conceptual model, there are two perspectives created by the SDP conceptual model. The application, generic service and service component planes provide a service-

oriented perspective on the SDP. For instance, customers view the telco as offering ser-

vices (applications) and perceive they interact with these services directly. Also, developers view the generic service plane as a resource of generic services with interfaces to orches- trate into applications. The developer’s view is limited to the generic service plane, while the telco is able to view all planes. For example, the telco views the service component plane as a resource of service components with APIs to orchestrate into generic services. The telco also views the service function plane as a resource of service functions with APIs to orchestrate into services components. In these service-oriented views service technolo- gies, implementations and distribution is hidden by the planes and service interfaces. The service function plane and infrastructure plane provides a functional-oriented view on the SDP. In this view the telco perceives the infrastructure plane as a resource of technology and distribution specific capabilities to be abstracted and integrated into services functions. The SDP conceptual model incorporates the telco OSS/BSS, such that each plane and its services are managed within a management environment. Like the IN conceptual model,

a managed environment administers applications accessing generic services, service inter- actions, all services and telco infrastructure. Each plane contributes functionality to the management environment. For instance, a service component plane implementation may provide management functionality to administer service components. Also, services in all service planes may abstract OSS/BSS functionality that is used in this management envi- ronment. Like the IN and TMN a separate management architecture may be defined, based on the SDP conceptual model. The management architecture may reuse the SDP conceptual model’s technology neutral planes, services and interfaces. Thus, the management architec- ture may promote standard-based SCE and SME using the planes’ services and interfaces.