Hi Kevin
Thanks for your reply. That helped me a lot. I’m using Geoserver with the 
direct integration of GWC, so I’m more interested about that at the moment.

What do you mean ”if the request does align (to the grid)…”? The request 
coordinate system is set to be the same as the cached layer’s coordinates 
system?

How does the Geoserver choose which set of the preseeded tiles it is using at 
different zoom levels? Is there any tolerance or does it has to be the exact 
scale from the gridset when it returns the tile, otherwise it cache it?

Ville Jussila

Lähettäjä: Kevin Smith [mailto:[email protected]]
Lähetetty: 14. lokakuuta 2015 2:36
Vastaanottaja: [email protected]
Aihe: Re: [Geoserver-users] Geowebcache - manual

The GeoServer GWC docs are here: 
http://docs.geoserver.org/stable/en/user/geowebcache/index.html

The published zoom levels are the zoom levels at which GWC will attempt to 
serve tiles.  The cached zoom levels are the levels at which it will cache the 
tiles it serves.

The integrated mode works like this:

A request comes in to the GeoServer WMS.

GeoServer checks if the request has the "tiled" parameter set.  If not it 
handles the request normally.

If tiled is set, GWC will attempt to handle the request as if the request had 
been made directly to GWC.  If the request doesn't align to the grid it will 
fail.  If the request does align, it will check the cache, and return the tile 
if it exists, otherwise it will request the image from GeoServer directly and 
cache it.

If GWC fails to handle the request, GeoServer then tries to handle it directly 
(without any caching)  This handles anything that wasn't aligned to a tile grid 
that GWC knows about.

When using WMS-C, the zoom level and scale is computed from the request. The 
request includes the extent of the image and the size of it.  GeoWebCache can 
use this to figure out a matching Grid/Zoomlevel if there is a matching one, 
GeoServer can use it to figure out a scale for the purposes of scale dependant 
styling.

--
  Kevin Michael Smith
  [email protected]<mailto:[email protected]>


On Wed, Oct 7, 2015, at 10:25 PM, Jussila Ville wrote:

Dear list,

I have some questions about Geowebcache. I’m running with Geoserver 2.7.0 and 
Geowebcache 1.7.0 and I’m using direct integration with Geoserver WMS.



First. Is there any webpage or manual about the Edit  Layer’s fourth tab, Tile 
caching, where is some info about Tile caching and what does these parameters 
do? Example what is Published zoom level parameters for?



Second. How does Geoserver use tiles and how does it choose which set of tiles 
it is using? Does it use the Scale level which is used at gridset or where? I 
would like to tile my map at one certain zoom level, example 1:25000 and use 
those tiles also at level 1:30000, 1:5000 etc. At bigger scale levels I want to 
use original datasource. Is this possible?



Many thanks



Ville Jussila
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