[Tilecache] WMS-T support

[Christopher Schmidt]

On Tue, Jun 02, 2009 at 11:21:10AM +0200, Guillaume Sueur wrote:
> Hi,
> 
> I'm only thinking loud here, because the subject interests my own 
> projects. Do you think that a Tilecache approach is the best for dealing 
> with time data ? Doesn't this aim to build many cache dirs which will be
> rarely used and maybe never again ?

The Disk cache is not the only cache that TileCache has. memcached would
be an ideal candidate for this type of data, allowing you to set up a
host/number of hosts with memcached, and depend on memcache's LRU
behavior to clean up your cache for you.   

> More widely, when the parametric set of the request can have many 
> different values, is it wise to build a cache for each requested ? IMHO 
> a standard proxy (squid or whatever) could be more appropriate and 
> easier to maintain on a disk size or time basis. Am I wrong ?

Only if you're assuming that the cache isn't already cleaning up based
on LRU rules, which isn't neccesarily true.

> Best regards,
> 
> Guillaume
> 
> 
> Jim Groffen a écrit :
> > Hello,
> > 
> > I've finished the work on the WMTS implementation in
> > TileCache, but I need to:
> > 
> > - update it to the main trunk version
> > - improve the docs and maybe add more doctests
> > - incorporate any feedback to get it contributed
> > 
> > The work was done for OWS-6 and is a RESTful implementation,
> > I haven't implemented the KVP interface.
> > 
> > A major difference is The way you define the coverage of
> > your tiles, this needs some nice documentation to make it
> > as easy as possible.
> > 
> > There are only a couple of concerns I can see with my
> > solution and its impact on TileCache. One of which is how
> > I had to extend the config file reading. It's backwards
> > compatible, but adds complication. In short the normal
> > behavior of TileCache is to treat all sections as a layer
> > definition except for an options section. My change added
> > an option to the options section that allows you to list
> > config sections that are to be treated as TileMatrixSets
> > and not layers. This has no impact on existing config
> > files but the changes are in Server.py and not small. I
> > tried to have as few changes impact files besides the
> > wmts.py layer and service files as possible.
> > 
> > I'll hopefully have a patch prepared some-time next week,
> > so I can get some feedback.
> > 
> > Regards,
> > 
> > Jim Groffen.
> > 
> > -----Original Message-----
> > From: tilecache-bounces at openlayers.org [mailto:tilecache-bounces at openlayers.org] On Behalf Of Christopher Schmidt
> > Sent: Tuesday, 2 June 2009 6:51 AM
> > To: Brian Walawender
> > Cc: tilecache at openlayers.org
> > Subject: Re: [Tilecache] WMS-T support
> > 
> > On Mon, Jun 01, 2009 at 03:38:48PM -0500, Brian Walawender wrote:
> >> Hello,
> >>
> >> Can I make WMS-T requests to tilecache?   My WMS requests look like:
> >>
> >> radar =  new OpenLayers.Layer.WMS( "TWX",
> >>         "http://
> >> 216.38.80.111/cgi-bin/mapserv?map=/usr/local/mapserver_config/TWX_time.map",
> >>         {
> >>                layers: 'TWX_N0R',
> >>                transparent: true,
> >>                time: '2009-06-01T15:55',
> >>                format: 'image/png'
> >>         }, {
> >>                singleTile: true,
> >>                isBaseLayer: false,
> >>                opacity: 0.9
> >>         }
> >> );
> >>
> >> My tilecache requests would look like:
> >>
> >> tc_url = ['http://radarcache.srh.noaa.gov/tilecache/tilecache.py'];
> >>
> >> radar = new OpenLayers.Layer.WMS( "State Borders", tc_url,
> >>         {
> >>                layers: 'TWX_N0R',
> >>                transparent: true,
> >>                format: 'image/png'
> >>        }, {
> >>                singleTile: false,
> >>                isBaseLayer: false,
> >>                opacity: 1.0
> >>        }
> >> );
> >>
> >> Is time a recognized param for tilecache?
> > 
> > No.
> > 
> > I feel like fredj wrote a patch that would allow you to create different
> > cache directories based on a specific parameter in the URL. However, I
> > don't remember ever integrating it, so there's a good chance that it got
> > lost in mailing list traffic. I would say that this would be the place
> > to look -- either in the code or in the mailing list for such a thing.
> > (Perhaps fredj can find it more easily, if he's listening.)
> > 
> > 
> > Regards,
> > --
> > Christopher Schmidt
> > MetaCarta
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-- 
Christopher Schmidt
MetaCarta