Bionic Buffalo Tech Note #116: Supporting Pegasus/ISA Services in MHP and OCAP Environments
“Bhutan” is Bionic Buffalo's project name for its OCAP product, and “Palestine” is its project name
for its MHP product. As OCAP is built on MHP, the Palestine software is included in the Bhutan
Establishing Interactive Sessions
Before any other network interaction takes place, the set-top-box (STB) must establish a session with
the network. MHP specifies (Chapter 6, Transport Protocols) the use of a subset of the network-
independent protocols defined in ETSI ETS 300 802, which in turn are derived from the DSM-CC
User-Network (U-N) protocols specified in ISO/IEC 13818-6.
The Pegasus Session Setup Protocol (SSP) is also a subset and specialization of the same U-N
protocols. Therefore, session establishment in Pegasus networks is an easy variation of the same
process in MHP/OCAP networks.
Session establishment per se is not associated with any defined API, although launching some
applications or services might indirectly trigger a new session. (Multiple simultaneous sessions are
supported.) MHP/OCAP applications need not be aware of this process, and may at this phase remain
oblivious to their use on a Pegasus/ISA network. (Note that although DAVIC 1.4.1, Part 9, Annex N,
defines a User-Network API, that API is incomplete and not of much use.)
If the STB's initial session uses SSP, then the only special requirement for the STB middleware is to be
configured to establish the initial session accordingly. For secondary sessions, the Palestine software
can be configured to recognize certain network addresses and URLs as pertaining to Pegasus/ISA
networks, so the use of SSP will be automatic. This is accomplished by calling routines (modifiable by
the STB implementor) which decide if a given address or URL is expecting a Pegasus protocol.
Bionic Buffalo recommends, however, that any Pegasus sessions be secondary, initiated from primary
MHP/OCAP sessions. This provides more flexibility and functionality to the end-user, and is likely to
cost nothing at all since deployment of MHP/OCAP STBs is likely in most cases to be accompanied by
some form of new (additional) server to provide enhanced services in conjunction with the
Minor additional configuration of the STB is necessary to provide some application-specific data to the
server. Another callback mechanism (similar to the one used to identify Pegasus network addresses
and URLs) is used so the implementor can provide the necessary data to the Palestine middleware.
In the MHP/OCAP model, services are programs provided through the network. Video-on-demand
(VOD) is considered a service. The
is the abstract view
of a service. MHP (and, therefore, OCAP) extends the
definition of services to
include various DAVIC services, which, in turn, include some DSM-CC services.
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