Mapping the IntesaGIS model to the EuroRoads model Alberto Belussi Università di Verona Giuseppe Pelagatti, Mauro Negri Politecnico di Milano ESDI Workshop on Conceptual Schema Languages and Tools ISPRA Octobre 2005 Translation exercise and discussion points about CSL

2 Outline of the presentation The role of GeoUML in Italy Translation between the IntesaGIS model and the EuroRoadS model CSL and Interoperability Conclusion

3 What is GeoUML? GeoUML is a conceptual schema language based on UML and the ISO standards (19109 “Rules for application schema” and “Spatial schema”) which was defined in the context of the Italian IntesaGIS project. It was used for the content specification of the core national spatial database of the Italian SDI. Interoperability was not the main target of the IntesaGIS project.

4 What is GeoUML? The main contribution of GeoUML is: the introduction of graphic constructs to represent a reference set of spatial integrity constrains (topological and structural constrains) in an application schema.

5 GeoUML and Interoperability There are currently some pilot projects in regional agencies (Lombardy and others) that aim to apply the IntesaGIS specification, focusing in particular on interoperability.

6 Translation exercise: models manipulation In the next pilot projects, we plan to develop some prototype tools for supporting the design of application schema in GeoUML and interoperability. We need specific tools since we want to represent graphically spatial integrity constrains. These tools are based on a repository for GeoUML application schemas (models). GeoUML repository GeoUML models Different representations Tools in JAVA

7 Translation exercise: translating models to XMI On of the Java tools will produce the XMI representation of a GeoUML model. In the XMI representation integrity constraints become OCL expressions, thus allowing the maximal compatibility with XMI tools without loosing information. GeoUML repository GeoUML models with spatial integrity constrains GeoUML models in XMI with OCL constraints XMI generation

8 Translation exercise: data translation approach In order to map one model M1 onto another model M2, provided that they share a common meta- model, it is necessary: to define a semantic mapping between the concepts of M1 and the concepts of M2 and a syntactic mapping between the data structures of M1 and the data structures of M2 Defining the GML representation of a model is very useful for both model and data translation, since tools based on XSL can be used to define a syntactic mapping, so that a XSLT parser can be used for data translation.

9 Problems of the proposed data translation approach Model M1 in GeoUML Data structures Integrity constraints Common Model in UML Data structures xsd files based on GML M1a xsd M1b xsd M1x xsd …… M1a xml M1b xml M1x xml …… xml file containing data XSLT transf. XMI M1 XMI CM Semantic mapping XSL mapping Syntactic mapping CMa xsd CMb xsd CMx xsd …… CMa xml CMb xml CMx xml ……

10 Translation exercise: Common model EuroRoads

11 Translation exercise: IntesaGIS model

12 Generation of xsd file GML-based from the IntesaGIS model We developed a prototype of a tool for generating the XML schema (GML based) given a GeoUML model stored in the repository (OGC r4, ISO 19136) GeoUML repository GeoUML models file xsd XMLschema GML-based Tool in Java

13 Generation of xsd file GML-based from the IntesaGIS model

14 Generation of xsd file GML-based from the IntesaGIS model

15 Syntactic mapping using XSLT... MainRoad FirstClass SecondClass ThirdClass FourthClass...

16 Data translation from IntesaGIS to EuroRoad We could not perform data translation on real data since at the moment we have no available data conforming the IntesaGIS model.

17 Problems arised during translation exercise XMI representation of the EuroRoad model is focused on data structures, semantics specification is avalable only in additional documents  no integreted support for semantic mapping (what is a main road?) traslation of geometry from one type of GML to another one (for example, translation from Compositecurve to Curve) might require computational geometry algorithms. This is not directly supported by XSLT.

18 Conceptual Schema Language issues In our opinion, a CSL should: 1. be UML-based and include a set of standard geometric types 2. support specification of spatial data properties (integrity constraints) and not only data structures. 3. guide the generation of GML schema for the representation of data in XML in order to facilitate XSL trasformations. 4. support different levels of interoperability

19 CSL: support integrity constraints specification CSL Geometric type Spatial integrity constraints UMLspecific typesspecific OCL expressions UML + Simple Feature Access common types specific OCL expressions on common types UML + Spatial Schema common types + complexes specific OCL expressions on common types + structural constraints UML + Spatial Schema + OCL templates common types + complexes common OCL templates (topological and structural constraints)

20 CSL: guiding the generation of GML schema CSL XML schema GML-based derivation UMLspecific encoding rules UML + encoding rules for Simple Feature Access common elements for geometric types (only primitives in XML files) UML + encoding rules for Spatial Schema common elements for geometric types (also complexes in XML files) UML + encoding rules for a profile of the Spatial Schema (with or without complexes, with or without 3D) common elements for geometric types and less options in geometric elements UML + a profile of the Spatial Schema and complete encoding rules (ISO 19136) common encoding rules

21 CSL: support different levels of interoperability Pure data exchange (lower interoperability level) Distributed data access Distributed data update (higher interoperability level) A CSL should be able to specify common application schemas for all interoperability levels.

22 Conclusion A Conceptual Schema Language for supporting interoperability has to contain: A set of standard geometric types: a profile of the Spatial Schema (a core Spatial Schema). A set of encoding rules for model translation in GML. A Conceptual Schema Language should also support the specification of data propeties (e.g. spatial integrity constrains).