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From an ArcGIS Server (9.3.x or 10.x) instance, can anyone confirm if REST HTTP response headers are modified when the data within a layer is updated?

For example, if I query a layer at time x and get a 200 OK response and E-Tag y and I query the same dataset at a later date, I'll generally receive a 304 Not Modified response with the same E-Tag. However I'd expect the E-Tag to change and to receive a 200 OK status if the layer data changed, is this the case?

If this is not the case, is there a way to test if data has changed since a particular date without actually pulling the data down.

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If this is not the case, is there a way to test if data has changed since a particular date without actually pulling the data down.

Whether or not this is the case, if you're just speaking HTTP methods, then you should be able to use a HEAD request.

An HTTP HEAD request is the same as an HTTP GET request with the exception that the response does not include the data.

You could use cURL (https://curl.haxx.se/) to generate such a request like:

curl 
  --request HEAD "http://your.service/ows?service=WXS&request=...&"
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  • Hi! Thanks for your answer. I'm specifically interested in ArcGIS server REST APIs. Yes, one would hope that they'd follow HTTP conventions, but I haven't been able to confirm if they do expire ETags (or provide some other way) to identify if a change has happened.
    – Hamish
    Commented Nov 3, 2016 at 23:33
  • Some things to consider then, can anyone confirm if REST HTTP response headers are modified when the data within a layer is updated There's no such thing as a REST HTTP response header, only an HTTP response header. ETags are often disabled, so probably shouldn't be relied upon as a means of determining changes.
    – nmtoken
    Commented Nov 4, 2016 at 8:54

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