Hi, Andrea,
I saw the "CAPABILITIES_CACHE_CONTROL_ENABLED" flag, and that's what I've
been using.
I agree with what you're saying, I expect the etag (which is, I believe,
the same token used in the conditional request) would need to be extended
with non-directly-catalog related information (or have a "don't cache"
value). I think it is currently "<catalog load time>-<update sequence>". I
will chat with Quinn.
Thanks for your response,
Dave
On Tue, Apr 4, 2017 at 2:45 AM, Andrea Aime <[email protected]>
wrote:
> Hi Dave,
> the callback in question extends the official OGC conditional capabilties
> request (based on the
> update sequence number) to non compliant clients that can do HTTP
> conditional requests instead.
> So the answer would be, "if something changes, you'd have to increment the
> update sequence,
> since your caps document changed".
>
> However, I understand and agree this is indeed a problem, the capabilities
> document can change
> due to dimensions, but also due to security, without anything touching the
> GeoServer configuration (which
> would bump the update sequence).
>
> As a quick fix, there is already a CAPABILITIES_CACHE_CONTROL_ENABLED
> envvar/sysvar/servlet context variable
> that can be set to false to disable the callback.
>
> As a longer term fix, the callback should probably be modified to identify
> elements making the caps
> dynamic. Like, for example, scan the layers available to the current user
> and create a digest out of them
> (fixes security) and if during the scan any has dimensions, uh, probably
> disable the conditional request fully.
>
> On the background, there is still the issue of proper OGC clients making
> update sequence based conditional
> request, those will still fail to notice something has changed... this
> mapserver ticket has enough information
> about it without you needing to read the OWS specifications:
> https://trac.osgeo.org/mapserver/ticket/2384
>
> Hum... from what I read, the "etag" computed above could also be used for
> conditional negotiation at the OGC
> level.
>
> Cheers
> Andrea
>
>
> On Fri, Mar 31, 2017 at 8:06 PM, Dave Blasby <[email protected]>
> wrote:
>
>> Hi,
>>
>> I noticed that the GetCap document was not up-to-date. When I dug into
>> it, I found that CapabilitiesCacheHeadersCallback was returning a 304
>> (i.e. no changes).
>>
>> However, this is a timeseries dataset (ie. Time Dimension tab on Layer
>> Publish).
>>
>> (i.e. a GeoGIG or PostGIS dataset with a time column)
>>
>> The issue is that the dataset is changing. A new Time value is inserted
>> into the dataset - the getcap (set to LIST) should show this new value.
>> However, the document is cached because the catalog hasn't detected any
>> changes.
>>
>> We talked about this earlier ("Time dimension on Vector Layer is SLOW")
>> and decided that caching this information is inappropriate (and I agree)
>> for this reason.
>>
>> What should be done about this?
>>
>> Thanks,
>> Dave
>>
>>
>>
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>
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