[Smwg] TGFT - a couple of points.

Barkley, Erik J (3970) erik.j.barkley at jpl.nasa.gov
Thu Dec 21 19:27:34 UTC 2017


With regard to file overwrite protection, to the best of my knowledge the WebDav LOCK method can be used to prevent file overwrites. I am certainly a long ways from being any kind of expert on WebDav, but it strikes me your question about using it somewhat parallels the approach of having gone through the XFDU definition to then develop a more restricted/to the point schema for TGFT in terms of payload. We do obviously have then the same sort of question with regard to the exchange protocol itself. My initial sense is that even though WebDav provides more than we need, it is still relatively straightforward and supported industry protocol. As such, there may be value in profiling this protocol for the somewhat simpler needs of TGFT with the understanding that we would then have the ability to offer more should application of TGFT indicate that is needed.  It does indeed sound like a good discussion topic for the telecon in January.

CSSM Colleagues,

Please allow me this opportunity to thank everyone for all of the excellent good work throughout this year and wish everyone a wonderful Holiday Season!

Best regards,

From: SMWG [mailto:smwg-bounces at mailman.ccsds.org] On Behalf Of Colin.Haddow at esa.int
Sent: Thursday, December 21, 2017 9:11 AM
To: CCSDS SMWG ML (smwg at mailman.ccsds.org) <smwg at mailman.ccsds.org>
Subject: [Smwg] TGFT - a couple of points.

Dear all,
                 I've finally had some time (necessary as I'm certainly not an http server guru and getting Apache set up is not intuitively obvious...) to play around with http and WebDav (Using Apache 2.4 on SLES 12) and can report the following;

  1.  With respect to the possible 4GByte file size limit we had some concerns about my tests on the afore mentioned platform indicate that this is not an issue. I uploaded a 5.7GBytes file successfully.

  1.  With the implementation of both the PUT and POST methods that come with WebDav in Apache 2.4 if a file with the same name as an existing file is uploaded then the existing file is overwritten. So some sort of naming convention will be required.

Now a question for all of you to consider over the Festive break (at least those of you that are not already on holiday). We had identified WebDav back in the early days of the TGFT concept, however since then things have changed and we now only need one operation, http PUT or POST (probably PUT). Both of these are in the basic http specification, i.e. WebDav is not required for them. So the question is do we really need WebDav or should we just use http/https ?, its worth noting however that as far as I can tell, and if anybody knows differently please correct me, that at least in Apache if WebDav is not used it is necessary to provide scripts to implement PUT and POST.

To be discussed at our January WebEx I guess.

Anyway a Merry Christmas and a Happy New Year to one and all.


Dr. Colin R. Haddow,
HSO-GI, European Space Agency,
European Space Operations Centre,
Robert-Bosch-Str 5,
64293 Darmstadt,

Phone; +49 6151 90 2896
Fax;      +49 6151 90 3010
E-Mail;  colin.haddow at esa.int<mailto:colin.haddow at esa.int>

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