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EVE Central Marketstat API returning outdated data
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Certainlynot Analt
Doomheim
#1 - 2013-06-10 23:11:16 UTC
I have a Google Docs spreadsheet that pulls pricing information from EVE Central. Recently, it's started returning stale prices for certain typeids and not others. This is despite EVE Central's actual website displaying up-to-date pricing information.

A sample call:

=IMPORTXML("http://api.eve-central.com/api/marketstat?usesystem=30002659&typeid=1&typeid=2&typeid=3&typeid=4&typeid=5&typeid=6", "/evec_api/marketstat/type[@id='"&B3&"']/buy/max")

I'm at my wit's end. It only happens for certain classes of goods, for some reason - e.g. t1 variants will be outdated while the separate sheet that handles t2 stuff will be pulling up-to-date prices.

Any ideas?
Certainlynot Analt
Doomheim
#2 - 2013-06-10 23:16:32 UTC
The problem appears to be caching-related. I just saw (doing direct api calls in a browser, not through Google Docs):

usesystem=bob&typeid=fred: outdated (repeatedly)
typeid=fred&usesystem=bob: up-to-date (once)
typeid=fred&usesystem=bob: outdated (repeatedly)
Certainlynot Analt
Doomheim
#3 - 2013-06-11 00:02:40 UTC
It is not a local caching issue. Outdated data is returned by multiple browsers, including ones I've not used recently.

Does EVE Central attempt to punish people submitting multiple marketstat calls by giving them bad data?
Certainlynot Analt
Doomheim
#4 - 2013-06-11 01:20:09 UTC
The problem persists if I run the HTTP request through a proxy. It doesn't appear to be some kind of deliberate, IP-specific mechanic, e.g. to punish hammering the server with requests.
Certainlynot Analt
Doomheim
#5 - 2013-06-11 01:32:33 UTC  |  Edited by: Certainlynot Analt
Verified.

http://api.eve-central.com/api/marketstat?typeid=34&usesystem=30002659

... returns a valid XML reply that has e.g. 4.96 as the maximum buy order, whereas the current maximum buy is 5.26 and the eve central site accurately has 5.26 as the highest current buy order. Several other people checked on different computers in their own browers and got identical, outdated information.

Dropping this for now, as I really don't think it's on my end. If I can help debug it, let me know.
iskflakes
#6 - 2013-06-11 10:56:51 UTC
The data seems fine to me. Looking at the website shows the highest buy order in Dodixie is 5.05 ISK, with 5.35 being the highest anywhere in EVE. Looking at the data on http://api.eve-central.com/api/marketstat?typeid=34&usesystem=30002659 it shows the maximum buy order in Dodixie is 5.05 ISK, as expected. Where is the problem?

-
Certainlynot Analt
Doomheim
#7 - 2013-06-11 21:49:06 UTC
Oh bah humbug. I was using the wrong system ID. I'd worked in a non-Jita system prior to moving to Jita and forgot to update usesystem=X in that one spreadsheet.

Compounding the problem was the fact that the particular item I was using as my test case wasn't moving very rapidly in the non-Jita system, so I was seeing persistent max buys and confusing it with some kind of caching problem.

Welp. Thanks for the help.