[Sidrops] XML in RRDP (Was: mft/ee validity time window alignment issue)

[Job Snijders <[e-mail]>]

On Fri, Jul 09, 2021 at 01:31:01PM +0200, Julian Reschke wrote:
> Am 09.07.2021 um 12:59 schrieb Job Snijders:
> > ... > If we are looking to decrease traffic, I'd first remove XML from RRDP as
> > that appears a 50% bloat compared to using DER as container :-)
> > ...
> 
> 1) Even with Content-Coding gzip?

Supporting gzip encoding is not a requirement for RPKI RPs. But indeed,
it helps reduce transfer size:

    https://rrdp.ripe.net/c85a5e87-ad1a-4b5a-b73f-8325877826fd/3059/snapshot.xml
    gzip encoded transfer: 67.9M
    non-gzip transfer: 141M

However, if we jokingly entertain 'tar' as a container format instead of
XML, the raw DER data can be gzip compressed to 57.5M! ~ 20% reduction :-)

My beef with the XML in RRDP is more than just the size: the requirement
to have to link a full blown XML parser library into an RP
implementation, while each RP already has a DER decoder, is bloat of
some sorts. XML in RRDP is merely used as a very expensive field
separator.

I know the original RRDP author was not specifically attached to XML,
and perhaps it was useful in the proof-of-concept phase. In the next
version of RRDP I'd recommend to get rid of the XML dependency.

> 2) How many RRDP requests are currently 304s, or could be 304s if
> clients and servers would take advantage of it?

Probably the majority. As far as I know most RPs implemented support for
'If-Modified-Since'.

A quick'n'dirty inspection of my publication webserver access log
searching for '304' requests shows that the most RPs support this
functionality:

    Apache-HttpClient/4.3.6 (java 1.5)   <-- unsure which RP this is
    OpenBSD rpki-client
    Routinator/0.8.0 - 0.10.0-dev
    fort/1.4.0 - 1.5.0

OctoRPKI & RIPE NCC's Validator don't appear to have If-Modified-Since
support.

Kind regards,

Job