[Tilecache] tilecache and getFeatureInfo

[Tim Schaub]

Steven M. Ottens wrote:
> Christopher Schmidt wrote:
>> On Tue, Jul 31, 2007 at 04:42:39PM +0200, Steven M. Ottens wrote:
>>   
>>> Hi all,
>>>
>>> I need both a cached WMS and the ability to do getFeatureInfo requests.
>>> Right now TileCache doesn't support getFeatureInfo and it would require
>>> a complex scheme to change the request url from tilecache.py to the
>>> mapserver.cgi url at the client side. 
>>>     
>> Why? 
>>   
> I need the ability to add layers dynamically. There are multiple 
> map-files involved so I cannot just replace tilecache.py with 
> mapserver.cgi. Although come to think of it I might be able to just use 
> tilecache.py?maps=/path/to/map.file&RestOfThe request. If Tilecache.py 
> ignores the map= bit, it should work.

I may have missed something from the start of the thread, but I can't 
imagine a setup that can't be handled by adding separate layers for 
GetFeatureInfo and GetMap requests.  If you're adding layers 
"dynamically" you can always add one for querying and one for tile requests.

>>> So I was looking into adding
>>> getFeatureInfo support to tilecache.
>>> I have a couple of questions:
>>> 1. Is it feasible at all?
>>>     
>> Anything is feasible, though it's somewhat against the design of TC, so
>> I'd be surprised by a patch I liked, I think.
>>   
> True, I've been hacking a bit but it's going to hack in deep, so that 
> might break the whole elegance of it.
>>> 2. Is it desired by other people and/or has soemone tried to write such
>>> a feature?
>>>     
>> Others have asked, and when I mentioned the idea of just changing the
>> URL at the client side, they seemed happy with that.
>>   
> Still, if you have multiple mapservers, you need to write filters for 
> each layer: if layerX then replace with mapserverY etc etc. This 
> requires an extra set of configurations and is error prone: if you 
> update a mapserver, you already need to update tilecache.cfg, but then 
> you also need to update the client.
>>   
>>> 3. I've no experience with python but from reading the code I figured
>>> that I need to do something like this:
>>>        add a function in Service.py "getFeatureInfo" this should call
>>> wms.fetch() once the WMS parameters are set.
>>>     In Client.py I should add support different request types and add an
>>> extra "Content-Type"
>>>
>>> sounds this about right? Am I forgetting something?
>>>     
>> That would probably work.  
>>
>> TileCache is a highly specialized piece of software: it serves tiles,
>> and metadata about how to request those tiles. Anything else is beyond
>> the scope of TileCache, from my point of view, though I might be able to
>> be convinced otherwise.
>>   
> Right, thanks
> 
> Steven
>> is not a WMS
>> server, and
>>   
>> Regards,
>>   
> 
> 
> 
> 
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