[MapProxy] Seeding - Conditional request based on timestamp?

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[MapProxy] Seeding - Conditional request based on timestamp?

ako_geo

I have several instances of MapProxy setup which all receive data from a central source (source servers are setup as tile servers).  The sources get updated frequently but not on a set schedule.  And the data that will get updated is at the higher levels of the cache ie: > level 15.  I am hoping to avoid running a cleanup and seed on each layer of each dataset to repopulate the cache, when there might not even be new data. 

So the question is - can the seed process be configured to query the source tiles to determine if the data has a later create/modified timestamp than the cached data on MapProxy?

Much appreciated, thanks.

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Re: [MapProxy] Seeding - Conditional request based on timestamp?

Oliver Tonnhofer-3
Hi,


> On 19.04.2016, at 15:44, andrew kovacs <[hidden email]> wrote:
>
> I have several instances of MapProxy setup which all receive data from a central source (source servers are setup as tile servers).  The sources get updated frequently but not on a set schedule.  And the data that will get updated is at the higher levels of the cache ie: > level 15.  I am hoping to avoid running a cleanup and seed on each layer of each dataset to repopulate the cache, when there might not even be new data.
>
> So the question is - can the seed process be configured to query the source tiles to determine if the data has a later create/modified timestamp than the cached data on MapProxy?


No, this is not possible. While it would be technically possible to extend MapProxy to pass the last-modification time of the cached tile to the source server (e.g. make use of HTTP cache control header), it would still need to make a request for each tile.


Normally you would create a coverage with the area of all your changes and use that coverage for (re)seeding. But this only works if you can get access to this information.



Regards,
Oliver

--
Oliver Tonnhofer  | Omniscale GmbH & Co KG  | http://omniscale.com
OpenStreetMap WMS and tile services         | http://maps.omniscale.com




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