I would like to have semantic markup attached to resources. For example, an xml element could be used to define the units associated with the coverage value or the attributes of a feature. Web applications that consume such a resource could then use this information to make unit conversions automatically, for example to switch from Fahrenheit to Celsius, etc. Or units conversion could be implemented in a Geoserver extension, in the same way that one can now request a reprojection.
There are many more examples of useful semantic markup that would allow information that currently languishes in metadata, or in the user's expert knowledge, to be used by web applications. Examples: statistical type (categorical, ordinal, etc), uncertainty, "physical" concept associated with each attribute, temporal information. There are potential interactions with other Geoserver extensions- for example, knowing the statistical type of an attribute would allow filtering of the interpolation methods used in reprojection or resampling to allow only methods that are statistically valid.
In thinkGeo[1], we currently handle this need with an external xml file that links the resources we plan to use with concepts in ontologies that define the semantic information. And we are working on a fudge to insert a string into the Geoserver keywords that could then be parsed back into xml. But it would make a lot more sense (maybe) to have this incorporated into the ResourceInfo interface so it would be available internally in Geoserver as well as accessible through the Rest interface.
However, in proposing this I am concerned that such a change might snowball into a huge modification, which would be more than I would be willing to tackle. So before I spend too much time exploring this, I would like to know how massive an undertaking this might be. Your comments are appreciated. - Tara
[1] http://wiki.osgeo.org/wiki/ThinkGeo
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Tara Athan