#5 Possibility to subtype the type Query at plug-in level

[Irene Celino]

(copy&paste from http://wiki.larkc.eu/LarkcProject/WP5/FeatureRequests, contact Daniele Dell'Aglio for further explanations)
# Description: (Daniele's descrption and suggestions to solve it)
* I will use the alpha Urban LarKC Event Workflow to explain the problem: the first two plug-ins of this workflow are a Query Transformer and an Identifier. The first converts the ?SparqlQuery in a ?CityQuery, a subclass of Query containing information about the city involved in the input query, while the second receives as input the ?CityQuery object and use it to retrieve the events. In the new code structure we found two problems:
o the class in the LarKC model schema: the class Query and its subclass are described in an RDF model used by the platform. ?CityQuery was not described in the model... Luka and Alexey solved (temporary) the problem extending the RDF model in the platform, but it can't be a general solution for the future.
o the location of ?CityQuery class: the Transformer and the Identifier are in two separate projects, so where the ?CityQuery class should be located? If I put it in both the projects (its source code), it won't be recognized to be the same class. I tried to import it as a library and it seems to work (if I remember well); then, talking with Luka and Alexey we put it in the platform project (the deadline for the ISWC tutorial was near and we took the quickest solution).
* Summarizing this point, we'd like to have a way in order to define new kinds of Query (and more generally LarKC types passed by a plug-in to another one), defining:
o a smart way to extend the RDF model of LarKC types, eventually not the direct extension of the RDF model of the platform, otherwise if the number of subclass (defined by each plug-in developer) grows this model will be unnecessarily big. It will be great if LarKC platform can load only some "model extensions" with the definitions of the types used by the workflows involved in the execution;
o some indication regarding how to interact with the extended class: is the use of library containing the custom types the right way to do it?