Thread: Re: intermittent problems with station service

Started: 2024-05-29 12:52:39
Last activity: 2024-05-29 12:52:39
Topics: Web Services
John West
2024-05-29 12:52:39
Cool, thanks Tobias!
-- John


On Wed, May 29, 2024 at 12:47 PM Tobias Megies <tobias.megies<at>lmu.de> wrote:


https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465*issuecomment-2138050112__;Iw!!IKRxdwAv5BmarQ!ZzykRuyHMXnnNf_WNg2VpUZ5sHbDDQG6nc-PMssbhuFDx-mEWpN_Hg1VesVNSqhgrrkpCndDM1PEUDwJMYhfVVdfswAz$

cheers,
Tobias


On 29/05/2024 20:21, John West (via SAGE) wrote:
We might be dealing with two different issues, but perhaps we should
solve one at a time.

Well, OK, but the original issue was primarily about the XML problem. I
occasionally see the malformed gzip issue, but get the XML error
multiple times per day.

I'll look into turning off gzip in the obspy client, thanks!
-- John


On Wed, May 29, 2024 at 12:09 PM Rob Casey <rob.casey<at>earthscope.org
<rob.casey<at>earthscope.org>> wrote:



Hi John-


I have a couple of questions here: Is the gzip problem and the
malformed XML problem the same issue? Or are we dealing with two
different issues?


We might be dealing with two different issues, but perhaps we should
solve one at a time.

I'm using the obspy client, which handles the requesting in the
background. Is there a way to append headers to that client, or
would I have to rewrite my code to do that?


Not speaking from experience, but I note that the Accept-encoding
header addition is played out in obspy.clients.fdsn.client. I don't
see a way to externally configure this, so to test this, you'd need
to modify the code so that 'use_gzip' is set to false by default.
If that isn't enough, then you'd want to assert "gzip;q=0" where the
Accept-encoding header is written in that code.

Naturally, having the server on our end functioning suffiently well
with gzip turned off would be preferable. I am just not sure yet
what the side effects might be in making this change, including data
transfer performance.

-Rob



Thanks!
-- John


On Wed, May 29, 2024 at 11:45 AM Rob Casey
<rob.casey<at>earthscope.org <rob.casey<at>earthscope.org>> wrote:

Hi John and Philip-

Gillian alerted me to your posts. This has been a long
nagging problem that didn't present obvious solutions over the past
couple of years. We have had little to not staff time that we have
been able to place on this issue, either as we are deep in
infrastructure development in our new center.

That being said, one of our staffers, Dan, took a crack
at trying to find a pattern and look for a way to circumvent, if not
solve. He got to the stage where we realized that there were not a
specific set of distributed servers that were causing the problem,
it could come from any of the systems, just at indeterminate times.
Something with the fdsnws-station web service call causes it to go
to a multipart content mode that inserts byte size values and seems
to trigger gzip output. (thx. Tobias)

There is a client-based way that Dan suggested could get
around the issue, and that is to have the client request to not
receive gzipped returns. He describes it like so:



-------------------------------------------------------------------------
You can explicitly say "don't send gzip" by adding q=0
like this:

Accept-Encoding:gzip;q=0

With the following in my Python code:

headers = {"Accept-Encoding":"gzip;q=0"} # asks
server not to use gzip Transfer-Encoding
r = requests.get(url, headers=headers)

I get zero issues from station service.


-------------------------------------------------------------------------

So, you can try this out and see whether you get improved
results. In fact, it would be great to get outside evaulation of
this. To be sustainable, though, we need a server-side solution, so
Dan also suggested that there is a way to configure Tomcat to not
opt for gzip output. This is something that we should be able to
try out in beta and see if that doesn't break something else.

Regards,

-Rob




On May 29, 2024, at 10:23 AM, John West (via SAGE)
<webservices-bounce<at>lists.ds.iris.edu
<webservices-bounce<at>lists.ds.iris.edu>> wrote:

Tobias is apparently having trouble posting to the mail list.
He has opened an issue on github to track this problem:

(
https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465__;!!IKRxdwAv5BmarQ!by8qJhcaNx0UirQy7fS_eIIjHB8u0U2EWHK7pbf4dlNmM_b6xEZRmMWLnzNsh2K773S2lj2fV1OqRhKvC-GfnNNFvzDT$
<
https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465__;!!IKRxdwAv5BmarQ!by8qJhcaNx0UirQy7fS_eIIjHB8u0U2EWHK7pbf4dlNmM_b6xEZRmMWLnzNsh2K773S2lj2fV1OqRhKvC-GfnNNFvzDT$>
)

-- John


On Wed, May 29, 2024 at 10:59 AM Tobias Megies
<tobias.megies<at>lmu.de <tobias.megies<at>lmu.de>> wrote:
Hi John,

yes, that's what I meant. My best guess was that the service
discovery
was creating the issue, because it's the only time we do
multiple
requests in parallel.
But yes, I can see that something also sometimes goes wrong in
"normal"
requests after the client initialization. Seems like a server
issue to
me but not 100% sure yet.

Can you maybe mention that github ticket I made on the ML

(
https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465__;!!IKRxdwAv5BmarQ!by8qJhcaNx0UirQy7fS_eIIjHB8u0U2EWHK7pbf4dlNmM_b6xEZRmMWLnzNsh2K773S2lj2fV1OqRhKvC-GfnNNFvzDT$
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https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465__;!!IKRxdwAv5BmarQ!by8qJhcaNx0UirQy7fS_eIIjHB8u0U2EWHK7pbf4dlNmM_b6xEZRmMWLnzNsh2K773S2lj2fV1OqRhKvC-GfnNNFvzDT$>
), my mails don't go through,
my old IRIS account has my old mail sender address and I made
anew
account on EarthScope but no luck with that either.


cheers,
Tobias


On 29/05/2024 17:38, John D. West wrote:
Hi, Tobias.

I changed line 21 of my sample code to: DCclient =
Client('IRIS',
_discover_services=False)

Is that what you had in mind? It doesn't make any difference,
the code
still generates errors on random networks.

Thanks!
-- John


On Wed, May 29, 2024 at 9:29 AM Tobias Megies
<tobias.megies<at>lmu.de <tobias.megies<at>lmu.de>
<tobias.megies<at>lmu.de <tobias.megies<at>lmu.de>>>
wrote:

Hi John,

a quick fix is this:

client = Client(_discover_services=False)

This skips service discovery (parsing the server side
WADLs) and makes
it so custom parameters Earthscope has can't be used, but
it should be
fine unless you do some real fancy requests.

cheers,
Tobias

On 29/05/2024 17:26, Tobias Megies wrote:
I opened an issue on github to track the issue:



https://urldefense.com/v3/__https://github.com/obspy/obspy/issues/3465__;!!IKRxdwAv5BmarQ!YbAqxDBWoNH9JDXLefMCt-N51qul5iRqXOqZKQeXCts8UL-jBXiT5LuOqCUjiwxkfp-C3ui9CONDDvIMI3gpakDxgJgS$
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cheers,
Tobias


On 29/05/2024 04:19, John West (via SAGE) wrote:
Hi!

I'm calling the station service using the
obspy client.get_stations()
method, and getting randomly distributed badly formed
XML.

Typical error message is something like: "Start tag
expected,
'<' not
found, line 1, column 1 (<string>, line 1)"

I've also had a few errors with: "Not a gzipped file
(b'a\r')"

The attached sample Python code sometimes runs
without error, and
sometimes generates multiple errors during a run. The
errors are
NOT
in the same places, they appear for different
networks on each run.

Any ideas?

Thanks!
-- John


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18:35:28 v.9bc884e1