Re: [dtn] BPv7 CDDL and CBOR tagging

[Carsten Bormann <[e-mail]>]

On Apr 3, 2019, at 21:14, Brian Sipos <[e-mail]> wrote:
> 
> 	• Indicate some likely places where CBOR tags can be used to augment encoded bundles for troubleshooting. In my mind, the reasonable tag sites are:
> 		• Tagging the whole bundle as "#6.55799(bundle) as a sentinel for content-type-scanning tools.
> 		• Tagging the "block-type-specific-data" as "encoded-cbor = #6.24(bstr)" when it is in fact CBOR.
> 

Hi Brian,

can you indicate what the purpose of the tagging would be?

Tagging the whole bundle as 55799 would identify it as a CBOR data item, but not yet really as a bundle.  If the purpose is to facilitate working with generic CBOR tools on the data items, that may be useful if there are other formats flying around in the same space the bundle is being used.  If the purpose is to identify this as a bundle, why not go for a specific tag just for bundles?  55798 is still free…  Or any number that is even more visibly tagging (such as 25200, which would be visible in a hex/ASCII dump as ‘bp’, or maybe four-byte or even an eight-byte number).  I understand these tags would be stripped off for actual transmission through a convergence layer?

The encoded-cbor tag (24) is great for identifying embedded CBOR, but what do you do for the other kinds of block-type-specific data?  Sorry, it’s been a while since I looked in detail into the bundle protocol.

(Why is the CDDL in appendix B double-spaced, by the way?)

Grüße, Carsten