Service Discovery and Selection

Service Discovery and Selection Functions

The Service Discovery Function (SDF) and the Service Selection Function (SSF) are functions which provide information necessary to the UE to select an IPTV service following
The Service Selection Function (SSF) provides the IPTV Terminal Function with a listing of available services that the user can browse and select namely a Broadband Content Guide (BCG).
In the near future all services will be compliant with the DVB Broadband Content Guide specifications (ETSI TS 102 539) using TV-Anytime formats (ETSI TS 102323).

For each IPTV service, the following data is provided:

• An identifier associated to the IPTV service based on DVB Content Reference Identifier (CRID): this identifier is used by service control functions and media functions to identify the requested content when processing service initiation requests. In case of a VoD service, the identifier identifies exactly one content item. In case of a broadcast service, the identifier identifies a single channel among which the user can switch and normally delivered via multicast
• Metadata information in XML formats providing information about the available content as content name, content length or playout time, a content description and various other data fields allowing a deeper categorization of the content.
  

CRID resolution server architecture

Fraunhofer FOKUS implements a CRID resolution authority fulfilling the following requirements:

• The CRID server and the exchanged XML documents are compliant with the TV-Anytime specifications (ETSI TS 102 822).
• An API to access the server is provided to perform the following tasks:

1. removal of CRIDs no longer in use, special attention will be paid that removed CRIDs will never be recreated at a later time

2. resolution of CRIDs to one or more associated URIs

3. addition of URIs to existing CRIDs

4. removal of URIs from existing CRIDs

5. replacement of URIs

6. creation of unique CRIDs from specified URIs

• URIs handled by the server are not restricted and fully support RFC 3986

Access to the Server

For ease of use the CRID server offers an internal and a public API:

• The internal API is available by binding via library to access the server locally. The API is simplified such as returning only arrays with the resolved URIs.
• The public API is available by binding via library as well as accessing a web-server that forwards queries to the CRID server library.

Although the CRID protocol for URIs is described in RFC 4078 and the corresponding resolution procedure is shown in the TV-Anytime specification part 4, the simplified TCP/IP access via the http protocol mentioned in these specifications will be offered. This is enforced by the fact that the current system will receive TV-Anytime enabled streams right soon, and that a resolution authority discovery via an enhanced DNS server is not likely. Hence the CRID resolution authority will be remotely accessible via well-known http requests.