[Css-csts] Alternate TD-CSTS specifcation on CWE

[John Pietras]

CSTSWG colleagues -

As you may recall, last month I posted White Book version 0.2 of the
Tracking Data CSTS specification on the CWE. In that version, the
Buffered Tracking Data Message Delivery (BTDMD) procedure was derived
from the Framework's Buffered Data Delivery (BDD) procedure operations
by modifying two operations: (a) the NOTIFY invocation was modified to
add a new notification-type value ('start of tdm') and a new extension
parameter (tdm-data-content) that contains a octet string formatted as a
CCSDS Tracking Data Message (TDM) Header; and (b) the data parameter of
the TRANSFER-DATA invocation was refined to be an octet stream formatted
as a TDM Segment. Because the TDM Header must always be sent, once and
only once, before any TDM Segments can be sent, the state table for the
BDD procedure also had to be modified to require that a non-discardable
'start of tdm' NOTIFY invocation be sent after the successful start of
the procedure but before any TDM Segment-bearing TRANSFER-DATA
invocations are sent.

 

Since posting that version, I have come to realize that there is an even
simpler approach. I have posted White Book version 0.2A (for alternate)
on the CWE at URL

http://cwe.ccsds.org/css/docs/CSS-CSTS/CWE%20Private/Future%20Services%2
0using%20Toolkit/Tracking%20Data%20CSTS/TD-CSTS_W-0.2A.doc

 

also http://tinyurl.com/TD-CSTS-W-0-2A

 

In the 0.2A version, the TDM Header is carried as an extension parameter
of the START positive return, instead of in the NOTIFY invocation. The
advantages are:

-        The START positive return is already being sent, once and only
once, prior any invocation of the TRANSFER-DATA operation. There is no
need to define a new notification-type and separate extension parameter
to be sent in a non-discardable NOTIFY invocation; and

-        Because the START positive return is already being sent, the
BDD state table does not have to be altered for the BTDMD procedure -
the BTDM procedure simply and completely adopts the BDD state table.

 

I am therefore proposing that the version 0.2A draft be the basis for
further development of the TD-CSTS specification. I welcome any comments
on this draft document or its predecessor (the version 0.2 draft).

 

The 0.2A draft contains the markup changes to allow anyone who is
interested to see what the differences are between v0.2 and 0.2A. If you
are not so concerned about those differences, you can view/print the
document in Final view mode. Please note that the version 0.2A draft
also cleans up a handful of typographical errors from the 0.2 version.

 

Best regards,

John

 

John Pietras

GST, Inc. 

7855 Walker Drive, Suite 200

Greenbelt, MD 20770

240-542-1155

 

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