I am calling in some WMS layers using openlayers. One of the layers is a raster. I have it working fine. But how does this fit into the spatial database model? I thought a WMS is a protocol for handling vector data. How raster data stored? Are they within PostGIS? Does Geoserver handle raster data? Thanks so much!
WMS is a protocol for displaying picture of maps. WFS is a protocol for sending vector data to a client while WCS is a protocol for sending rasters to a client. The key difference is what ends up with the client, if the client needs to work with the data then you want to use a WFS or WCS but for most web mapping projects a WMS is a fine way of sending a picture of your map to them, it doesn't matter if the underlying data is a raster or a vector.
GeoServer handles raster data by reading the data from a file in the data directory. Exactly where and how it is read from depends on the data store you are using.