Hi,
Not GeoRSS feeds but the following SQL creates truncate commands for GWC in json format for all the mapsheeet numbers which are listed as updated in 2014. List of updated mapsheets is in table “aerials” and the geometries of the mapsheets are in table “a.mapsheet”.
Adjust the SQL for PostGIS and your tables, make a trigger and it should be possible to make your database into an active party which creates truncate requests immediately after the data has been changed.
select
’
curl -x cache.mmm.fi:800 -v -k -u admin:geoserver -XPOST -H “Content-type: application/json” -d "{‘‘seedRequest’’:{‘‘name’’:‘‘GWC_layer’’,‘‘bounds’’:{‘‘coords’’:{ ‘‘double’’:[‘’’
MbrMinX(one.geometry)||‘’‘,’‘’||
MbrMinY(one.geometry)||‘’‘,’‘’||
MbrMaxX(one.geometry)||‘’‘,’‘’||
MbrMaxY(one.geometry)||‘’‘’||
‘]}},’‘srs’‘:{’‘number’‘:2393},’‘zoomStart’‘:8,’‘zoomStop’‘:13,’‘format’‘:’‘image/png’‘,’‘type’‘:’‘truncate’‘,’‘threadCount’':4}}}" “http://host.com:8080/geoserver/gwc/rest/seed/GWC_layer.json”
’
from a.mapsheet as “one”
join “aerials” as “two” on (“one”.“mapsheeet_id” = “two”.“mapsheet_id”)
where “two”.“updated”=2014
-Jukka Rahkonen-
···
Jody Garnett wrote:
Part of the integration of GWC clears areas of the cache based on WFS-T transactions. You can produce a similar effect in a standalone GWC by giving it a georss feed.
Anyone up for turning your PostGIS changes into a GeoRSS feed 
Jody Garnett
On Thu, Aug 21, 2014 at 6:25 AM, Nachtigall, Jens (init) <Jens.Nachtigall@…5799…> wrote:
Hi,
I have a typical setup like:
PostGIS => GS => GWC => Browser.
Can I have preseeded tiles at GeoWebCache that are invalidated (i.e. get expired) on the fly based on caching headers?
That is, is the following possible?:
-
Browser re-requests a certain tile including If-Modified-Since header
-
GWC has a preseeded tile but needs to know if the tile is still valid. So GWC passes the request (still with If-Modified-Since) on to GS
-
GS looks up PostGIS to decide if tile is still valid or not. That is, if the data for the requested area has changed. Depending on that finding…
-
GS answers “304 Not Modified” or gives GWC the freshly generated tile
-
GWC updates its cache and passes answer along (either “304 Not Modified” or new tile)
I’ve read about Caching with Last-Modified or E-Tag headers at http://geowebcache.org/docs/current/services/responseheaders.html#last-modified-and-if-modified-since
However, this only handles the communication between browser and GWC. How about the “backend communication” between GS and GWC?
Best,
Jens
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