design choice: multi-threaded / asynchronous wxpython client?

[David]

>  Date is the time of the server response and not last data update. Data
>  is definitely time of server response to my request and bears no
>  relation to when the live XML data was updated. I know this for a fact
>  because right now there is no active race meeting and any data still
>  available is static and many hours old. I would not feel confident
>  rejecting incoming data as duplicate based only on same content length
>  criterion. Am I missing something here?

It looks like the data is dynamically generated on the server, so the
web server doesn't know if/when the data changed. You will usually see
this for static content (images, html files, etc). You could go by the
Cache-Control line and only fetch data every 30 seconds, but it's
possible for you to miss some updates this way.

Another thing you could try (if necessary, this is a bit of an
overkill) - download the first part of the XML (GET request with a
range header), and check the timestamp you mentinoed. If that changed
then re-request the doc (a download resume is risky, the XML might
change between your 2 requests).

David.