This is a document precipitated because I don't understand the inter-feature relationship under the TC/211 model, which is what the coverage schema in 19123 is based on. In essence, it explores how to model features with software to provide uniform access to attributes, associations, and behaviors, regardless of whether the feature type was constructed dynamically or is implemented directly in Java code. Along the way, the ComplexFeatures model is evaluated with respect to a specific set of requirements developed from the TC/211 meta model.
This document ping pongs back and forth between concepts in the ISO 19109 specification and how one might implement these concepts. My goal is to have a system where coverages are a type of feature, and can therefore be treated like any other feature. As expressed in the document, a simple formulation of this problem is: I need a model which implements meta layer concepts with classes and objects. The coverage effort pretty much requires an out-of-the-box solution because deadlines wait for no man. Therefore, you may regard this document as a pie in the sky target for long term implementation. However, there are two immediate alternatives for the coverage effort: direct implementation of the coverage interfaces in Java, or use of the eclipse modeling framework to support runtime modeling of the coverage framework (and back this model with Java classes). I have not yet thought of a way to implement coverages using the ComplexFeatures model due to some issues expressed in the 19109 primer. Of the two tractable solutions, (EMF and direct implementation), EMF is only attractive if the feature model types buy into it as well. Let me make this clear: uniformly using EMF is the only way I can see which accomplishes a coverage and feature unification. Let me also make clear that this does not mean dumping ComplexFeatures. EMF would replace those parts of ComplexFeatures which model features, leaving intact those parts which implement the fancy Xpath Xquery stuff which I don't know too much about. EMF is just full of promise at this point. I have not fully investigated it to ensure that it won't buckle under when I try to use it for coverages. However, the laundry list of requirements from TC/211 matches very nicely with the laundry list of features from EMF. If it does not live up to it's promise, then coverages will have to be implemented directly as Java implementations of the GeoAPI interfaces in pending and there will be _nothing_ to tie features and coverages together. Please yell at me if I'm missing a solution. I do realize I'm jumping into an area (features) where I have not invested as much thought as others. On the other hand, I don't have much more time for planning. Gotta start doing. I'd like to put this on the agenda for Monday's IRC and I'll try to be there for it. I added the ISO 19109 primer to the hotbox on the 19123 progress page. http://docs.codehaus.org/display/GEOTOOLS/ISO+19123+progress+and+future+plan Bryce ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
