[Css-csts] Reference Model Terminology for use in CSTS Specifications

[Takahiro Yamada]

John,

Suggested by Peter Shames, I reviewed your document entitled 
“TermsForCSTSProcSpecR1.” As you know, I'm editing a document called 
“Cross Support Service Architecture” for IOAG, which defines similar terms.

Since the purposes of these two documents are different (that is, your 
document will be used as the framework for defining SLE services, while 
mine provides a framework for characterizing any service that can be 
used for cross support), there is no need to use the same terms in these 
two documents. But it would be nice if we could use the same set of 
basic concepts for defining terms used in each document.

This note does not cover all of the terms used in these two documents, 
but I think I can show you an example of the differences that exist.

Let's start with cross support service.

(JP definition) Cross-support service: A set of capabilities that an 
object that belongs to one Space Agency provides to objects that belong 
to other Space Agencies by means of one or more ports, in support of 
spacecraft operations.

(TY definition) Cross support service: a function provided by a space 
Agency to support operations of a space mission of another space Agency.

I don't think there is a significant difference between these definitions.

So, let's go to the next step.

(JP definition) Cross support transfer service: A subclass of cross 
support service that provides a connection-oriented, access-controlled 
transfer of spaceflight mission-related data between Ground Element 
entities, realized through the invocation and performance of defined 
operations in accordance with defined procedures.

I'm not sure why so many words should be used here to define cross 
support transfer service, in which only one word (that is, transfer) is 
added to cross support service.

How should a cross support service that provides a 
non-connection-oriented transfer of mission-related data be called? This 
is not a cross support transfer service by definition.

How should a cross support service that provides a non-access-controlled 
transfer of mission-related data be called? This is not a cross support 
transfer service by definition.

How should a cross support service that provides a transfer of 
mission-related data between Space Element entities or between a Space 
Element entity and a Ground Element entity be called? This is not a 
cross support transfer service by definition.

More specifically, many projects use ftp for retrieving telemetry 
received and stored at a remote ground station. How should this service 
be called? This is a cross support service, but not a cross support 
transfer service by definition.

In my document, cross support services are categorized into the 
following service types:

- Forward delivery services,
- Return delivery services,
- Tracking services,
- Time services, and
- Voice and video services.

These categories are defined based on the basic functionality provided 
by services (that is, to deliver data, to perform radiometric 
measurement, to correlate clocks, etc.). How to access the services 
(that is, whether to use ftp or a special protocol) is an attribute (or 
sub-types) of these service types. Where the services are provided (that 
is, by a ground station, by a relay satellite, etc.) is another 
attribute (or sub-types).

Anyway, I'm interested in defining an architecture that can be used both 
as the reference framework for defining SLE services and as the 
reference framework for developing an IOAG service catalog and will be 
glad to work with you on this theme.

Best regards,
Takahiro Yamada.