Editor's Note: This holistic SearchTelecom.com series, Service delivery platforms: Changing the networking paradigm,...
telecom-industry consultant Tom Nolle looks at how SDPs fit into next-generation network architecture and the business advantages they provide for carriers.
Advanced service creation requires speed and agility. And a single difference between the current networking marketplace and the markets of the past is in the relationship between services and network infrastructure. This difference is the primary justification for a new model of service creation and the increased reliance on service delivery platforms (SDPs).
With advanced service creation, network resources and developers' applications can be composed into a service model from "prefabricated" components.
To remain competitive, network operators must foster a new model of layered networks, one that divides networks into a transport/connection layer, a service control layer, and an applications and features layer.
In the past, networks were built around a service concept, and demand was typically developed by deploying capabilities, then socializing their use. This is also known as the "build it and they will come" approach. Because network services were deployed at their own speed, not in response to market stimulus, the service delivery paradigms of the time fit well with the long capital cycles of service providers.
Today, network services are deployed quickly to exploit specific forms of market behavior. Social networking is a good example of this. If you can't enter a market quickly when the opportunity arises, there is little chance of carving out a survivable niche. While the notion of service features hosted on networks is inherently more flexible than the notion of service-specific networks, even hosted features don't go far enough toward providing flexibility, agility and service velocity. Although hosting decouples services from network equipment, it can still leave silos of incompatible, non-optimized service implementations.
Advanced service creation requires a different vision of layered networks, one that divides them into a transport/connection layer, a service control layer, and an applications/features layer.
Figure 1: The new vision of advanced service creation
This structure was first introduced in the PSTN model of Advanced Intelligent Networks (AIN) and has been expanded by work on the IP Multimedia Subsystem (IMS) and Next-Generation Network (NGN) by the 3rd Generation Partnership Project (3GPP), European Telecommunications Standards Institute (ETSI) and the International Telecommunication Union (ITU). Because SDPs must support both existing and evolving services, these models, including AIN, IMS and NGN, must be explicitly supported by SDPs, as well as the emerging Internet-driven models -- often called Web 2.0.
Advanced service creation must support four key elements
One of the key requirements for advanced service creation is support for the four fundamental elements of communications services as a standard set of tools so these elements are not implemented multiple times and in incompatible ways. This reduces the overall service deployment time through standardization and also makes it easy to create services that share information about users across service boundaries. The fundamental elements are:
- Identity: A reliable way of knowing who a user is and linking the logical concept of a user to an entity that can be authenticated to play a specific role (pick up a message) or receive a bill.
- Presence: The status of a user across all of the services that user can exercise. This is a critical element in deciding how to optimize service behavior to user practices. For example, should a given incoming call be routed to voicemail without ringing, or should a given email result in an IM alert to the user's cell phone?
- Location: The place where a given user can be found at a given time. This is a critical element for services that help users find things that are geographically nearby, but particularly for services that involve finding the user, including emergency 911.
- Demographics: Behavioral and characteristic data about users provides a clue to their commercial behavior. For any services that relate to buying, selling or advertising, demographic information is critical.
Middleware connects service-creation hardware/software
While a service delivery platform should provide all four elements in some way, other essential tools bind together the advanced service features and applications into services. In the SDP model of agile service creation, application and transport/connection resources are linked to the SDP via middlewarethat can consist of both software application program interfaces (APIs) and hardware protocols. The SDP provides the tools to support building applications and features, then connects these components into functioning services. Similarly, the SDP provides tools to exercise the standard interfaces being developed between transport/connection resources and services. An example of this is the Resource Access Control Facility (RACF) defined in ITU NGN.
In advanced service creation, a service-control framework, normally based on some form of service signaling, allows the user to commit network resources (or in voice terms, for example, to make a call) and activate special service features (again using a voice example, invoke call forwarding). Signaling "events" (hitting a key combination) result in the activation of a software-hosted feature through a standard interface. In the call-forwarding example, this might be the CAP/CAMEL protocol.
With advanced service creation, SDPs would be able to expose their applications/features via middleware in response to a wide variety of signal stimuli, not just a combination of phone keys. Similarly, both applications/features and service signaling could invoke transport/connection functions in a way that is both technology- and vendor-independent. This flexibility means that the network's connection resources and developers' applications and features can be composed into a service model at the service control layer to create a service from "prefabricated" components.
Fitting applications into service control logic
Put into this context, applications like IPTV and IMS are examples of structured service control logic, a model that is completely consistent with the way the ITU's NGN works interprets these applications. Because the IMS model supports the same basic calling services as PSTN/AIN and provides a way to quickly expand the carrier voice service features, it demonstrates the value of advanced service creation with legacy services.
The so-called "Web 2.0 applications" can also be created in a service control model. Service-oriented architecture (SOA) principles can be based on a variety of technical models, including Web services and the Internet model of Representational State Transfer (REST) that frames service and application components as URLs. Clicking on a URL can generate a signaling event just like pressing a telephone key. In fact, both types of events can activate the same features and behaviors in an advanced SDP implementation. This demonstrates that service-control applications can coexist in parallel (something the ITU standards also affirm) and that tools to create service-layer structures quickly can then be used to build services quickly as well.
About the author: Tom Nolle is president of CIMI Corporation, a strategic consulting firm specializing in telecommunications and data communications since 1982. He is a member of the IEEE, ACM, TMF and IPsphere Forum, and the publisher of Netwatcher, a journal in advanced telecommunications strategy issues. Check out his SearchTelecom.com networking blog, Uncommon Wisdom.