I want to be able to draw a bounding polygon and have my MapServer WMS layer return every feature within that bounding box. I have it working for a single point, but I would like for the query to return every single feature within a polygon. Is that possible with WMS GetFeatureInfo? I am using OpenLayers in Java with GWT. There is a bridge between Java and the OpenLayers JS.
You cannot get information for features within a bbox using a WMS getFeatureInfo. Please have a look at the WMS reference for getFeatureInfo.
You will see that according to the standards, you can only pass in points, not a bbox.
Instead, you could use a getFeature Operation on the WFS service.
The BBOX parameter allows you to search for features that are contained (or partially contained) inside a box of user-defined coordinates. The format of the BBOX parameter is bbox=a1,b1,a2,b2
wherea1, b1, a2, and b2 represent the coordinate values.
An example request involving returning features based on bounding box would be in the following format:
http://example.com/geoserver/wfs? service=wfs& version=2.0.0& request=GetFeature& typeName=namespace:featuretype& srsName=CRS bbox=a1,b1,a2,b2
(Please note, that I have linked to the geoserver site, instead of the actual OGC standards, as the Geoserver website is far more readable than the OGC standards.)