[Freegis-list] WMS WFS PostGIS architecture question.

[Arnulf Christl]

Peter Fischer wrote:
> Hello,
> 
> I have a question concerning the architecture of WMS/WFS and PostGIS:
> Is PostGIS just for WFS or could it be used also to store the card
> material for a WMS? - How typically a WMS stores its card material?
> Also in sort of a database? - Is it standardized? Or is the card
> material just stored in a directory/file structure without database
> functionality?

Peter,
we use PostgreSQL/PostGIS as datastore for the software GeoServer (Java) as WFS to access geometries (vectors). This is good to query for street address, name gazetteer, zoning data, floor map and if configured as transactional service it is also good for updating (editing) geometries via web. To visualize (render) maps we use the software MapServer (C++) that accesses the very same PostgreSQL/PostGIS database. 

That way we can use the best tools for the corresponding job that are on the market to produce optimized results. MapServer is fast, stable and has a powerful cartography but lacks WFS transactionality. GeoServer knows how to use transactions on a WFS and can write back but is less powerful on cartography. Late binding of both is done with the application framework Mapbender (PHP and SQL which incidentally can also be stored in a PG/PostGIS box, opening up even more possibilities). 

> Furthermore, I found the following PDF:
> 
> http://lists.refractions.net/pipermail/postgis-users/attachments/20020424/20dcffd7/OGC-OSS.pdf
> 
> On page 2 the WFS on the bottom acesses Rasters and Images. But I
> thought, WFS is just for vector data (features), stored in e.g.
> ESRI shapes or PostGIS, like the other two datasources. But is it
> really true like in this diagram that a WFS also can access raster
> images? - I thought this is normally done by WMS/WCS?

My personal take is to leave rasters outside databases, we have several high performing libraries and compressions algorithms so that there is no need to stuff all into a database. Raster output in most cases will either come from a WMS (nice but dumb) or WCS (there aint many but those few are real smart). 

Hope this helps,
Arnulf. 

> Please could anyone help to clear my confusion?
> 
> Best regards,
> 
> Peter.
> 
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