OWL2GRA

OWL2GRA Architecture

The figure bellow represents all the processes and modules that are presented in this project showing how an abstract ontology( described in a simple ontology specification language) is transformed into an OWL XML ontology that is then transformed into an AntLR attribute grammar.

Onto2OWL

Module Onto2OWL is the first layer of this project. Onto2OWL creates a specification file in the standard notation for ontologies specification, OWL-XML, from an ontology specification written in OntoDL, a Domain Specific Language to describe in a simple, easy to use, way the ontologies. This module is composed by two important parts. The first is a parser for the input file written in a DSL that we have specially designed, called OntoDL. The second part is a java class that manipulates the information gathered by the parser and generates the OWL-XML standard file.

The OntoDL file describe the basic information about an ontology: Concepts, Hierarchies, Relations and Links. So, you will find something like this:

• Ontology{
  • Concepts{
    • {concept1}, //the only thing that is mandatory is the name of the concept
    • {concept2, Description("some description")}, //it is possible to add some description
    • {concept3,Attributes[{attribute1 string},attribute2 int]}, //and/or someattributes also can be added for more detail
    }
  • Hierarchies{
    • {test1 > test2} //test2 is a sub-class of test1
    • {test2 > test3} //test3 is a sub-class of test2
    }
  • Relations{
    • {relation1}, //the only thing that is mandatory is the name of the property
    • {relation2 ,Description("some description")} //you can also put a description on the property
    }
  • Links{
    • {concept1 relation1 concept2}, //this style is mandatory first concept is related by the relation to the second concept
    • {concept3 relation2 concept1}
    }
  }

This module was created with the objective of generating OWL files from simple ontological descriptions of the domain. It can be used separately from the other components see the API.

OWL2DSL

With OWL2DSL it is possible to generate a grammar specification and a parser for a DSL to describe elements for the domain.

The main objective of this module was to generate a grammar that represents a certain domain specified by an Ontology written in any OWL standard. This grammar has a set of rules that are responsible for the generation:

• The first rule it states that if the concept is connected hierarchically to Thing, this concept it will be added to an cycle of super productions.
  • If A is_a Thing and B is_a Thing and C is_a A The result is:
    thing : (A|B)+ ;
• The second rule describe that every production would start with an ID that specifies the name of the instance of the concept on the LHS.
  • A : A{ Instance_A_ID ... } ;
• The third rule describe the hierarchies and means a Concept that is a super-class will have each sub-class as a symbol on a RHS alternative.
  • A : A{ ... [ C ] } ;
    C : C{ Instance_C_ID }
• The fourth rule describe the relations and is the same as last one but because it depends on the cardinality of the connections defined between Concepts have some differences.
  • A : A{ ... [ C ] [ {A relation1 B}+ ] } ;

DDesc2OWL

DDesc2OWL is the last module of the OWL2Gra. The purpose of this module is to populate the initial ontology that was used to generate the grammar.

This Module is very simple; it receives three parameters, that are files, and processes them in different moments.

• Grammar
  • The first important parameter is the path of the grammar file that was generated during the last phase. This grammar will need the Java class set (also generated at the previous stage).
• Ddesc
  • The second file is the DDesc input file. This file describes all the instances that will create the individuals on the ontology.
• Ontology
  • Finally, the last file is the original ontology that was used for the creation of the grammar by the OWL2DSL Module. This file will be processed again to rebuild the ontology in order to create the populated version.