[Tilecache] WMS-T support
Guillaume Sueur
no-reply at neogeo-online.net
Tue Jun 2 14:45:42 EDT 2009
This is actually very interesting, thanks to both of you for these clear
answers.
I have a 5 minutes data set (every 5 minutes, a postgresql database is
updated with forecasts for next 5, 10, 15, 20, 30, 40, 60 minutes)
related to roads.
I haven't decided yet to cache these images or not. MapServer
generation is fast enough to assume it can go live, and the use is
rather internal to the organisation. But I may give WMS-T a shot as it
sounds promising.
Best regards,
Guillaume
Brian Walawender a écrit :
> Guillaume,
>
> We are using the tilecache to serve radar data ( http://radar.srh.noaa.gov/
> ). Typically a radar image is updated every five minutes. We have about
> 130 radars across the US with each radar offering about 10 different
> products (layers). On a busy day, we our static image pages will get nearly
> 100 million hits. Typically those hits will be focused on the radars that
> have storms. For the most part an individual radar layer cache would be in
> use for about an hour, so even though we are constantly rolling through the
> cache directories, I think we are taking a tremendous load off our WMS
> server with the tilecache.
>
> The WMS-T is much more attractive than our current method which is very I/O
> intensive because we are rotating the base images and (attempting) to rotate
> the cache directories as a new image arrives.
>
> bw
>
> -----Original Message-----
> From: tilecache-bounces at openlayers.org
> [mailto:tilecache-bounces at openlayers.org] On Behalf Of Christopher Schmidt
> Sent: Tuesday, June 02, 2009 6:33 AM
> To: Guillaume Sueur
> Cc: tilecache at openlayers.org
> Subject: Re: [Tilecache] WMS-T support
>
> 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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