[Featureserver] featureserver and dynamic layers?

[Josh Livni]

Hi Bud,

Some answers inline:

> First a question on OpenLayers:  when loading a layer, does it always
> add a BBOX to the query sent to featureserver?  And does Openlayers
> automatically take care of re-querying featureserver during panning and
> zooming?
>   
Yes and Yes, as far as I know (this assumes for example you are using 
something like OpenLayers.Layer.WFS)

> So that leaves that the URL must specify what data one wants.  I
> suppose a simple (single table, no joins) generic case is quite
> straight forward to express in GET parameters.  Does that sound right?
>   
Not sure what you're asking, but yeah - as described in the 
featureserver docs, for PostGIS your config for a featureserver layer 
refers to a table or view in postgis.  So for joins you can create a 
view and reference that. 
> What I don't see very clearly is how querying relates to backends.  I'm
> very centered on PostGIS.  Is this something to do for postgis only or
> is this something to do for a group of backends that are "queryable"?
> (And which are those?)
>   
Different backends might support different querying (and other) 
capabilities.  I think it would be nice if, when adding some new feature 
to a datasource, it was considered what other datasources could use the 
same thing, and then make it more general.  But I don't think adding 
something good to just one datasource would be frowned on (as has been 
done to the postgis datasource in the past).

One thing that might help is if you can describe some specifics about 
the type of querying you need.  For example, I am planning to add 
something to the PostGIS datastore that will allow you to explicity 
state what kind of operator to use for matching in the queryable 
layers.   So then you could do something like 
&queryable=cost&cost__lessthan=15 ... this would translate to some SQL 
such as 'WHERE cost < 15'.   I would add support for just a few 
operators, but I think this could be powerful for a variety of cases 
(and would let me remove some ugly hacks I've added to some local fs 
projects).  So anyway, is this the type of thing you are thinking you 
are looking for when you say complex queries?  Or something else?

Cheers,

  -Josh