CURRENT RELEASE

The current release of the IDM Tools comprises 3 tools, as shown by the figure below:

1. the Model Browser, which provides a way of exploring the Conceptual Schema in a hypertext style that is different and complementary to reading UML diagrams;  this is useful not only for non UML experts, but also for experts who need to retrieve rapidly all information related to a given class.
2. the SQL Mapper, which allows to select a set of Feature Types from the Conceptual Model and generates an SQL Script for creating a PostGis Database – called INSPIRE DATABASE –  representing the selected Feature Types
3. the WFS Configurator, which produces a Configuration File enabling a Deegree WFS to access the Data contained in the INSPIRE DATABASE

Notice that for using the IDM Tools it is not necessary to install Enterprise Architect – these tools provide therefore free access to the Inspire Data Model.

MOTIVATIONS

The architecture of the IDM Tools is characterized by 2 main aspects:

• the support to the frontend service is provided by an SQL database system
• the structure of the database is produced by the UML models (not from the XSDs of the service)

This architecture is motivated by considerations regarding the performance of the services and the stability of the data models. We believe that a WFS service must be supported by a full-fledged spatial DBMS in order to obtain acceptable performance, especially in presence of one or more of the following requirements:

• the WFS service has to service queries (possibly many queries in parallel), not only predefined datasets
• the amount of data to access is large
• the data should be updated through a transactional WFS

Regarding the stability of the Data Models, we believe that the UML model will be more stable than the XSDs which have been derived from it, since

• the legally approved INSPIRE Data Specifications contain the UML model, not the XSDs
• the GML XSDs published by INSPIRE constitute only one possible encoding; other encodings may emerge in the future

A major investment which the INSPIRE Data producers will have to face in the next years will be the definition of the (semantic) transformation from their Production Data Models to the INSPIRE Data Model. Since the structure of the INSPIRE Database is derived from the UML model, using the UML Model and the INSPIRE database as the target of these transformations will safeguard these investments from changes in the encodings. In fact, in this architecture different encodings can be produced without affecting the (semantic) transformations.

PRELOADED DATA MODEL

The IDM Tools are distributed with a preloaded INSPIRE UML Data Model; in the current release this preloaded Data Model has been derived from the official Inspire 2010-04-26_r937.eap distribution. The derived model in .eap format can be downloaded from this site. The few transformations which have been applied to the INSPIRE Themes are due to the correction of some errors or to some requirements for GML encoding. The ISO package has been simplified and renamed as “selected ISO TC211”. A detailed description of these modifications is presented in the Preloaded Data Model panel of the tool.

 FUTURE DEVELOPMENTS

If the approach adopted by the IDM Tools will encounter the interest of stakeholders, we plan to develop it further in several directions:

• Validation of the INSPIRE Data Model: the procedures which have been applied for preloading the UML model can be transformed in a distributable tool for UML Schema Validation.
• Support for the transformation of data from existing datasets to the INSPIRE Database; the integration of existing tools into this architecture will be investigated (some work in this direction, considering as source database the Italian “National Core” – the Italian standard for GeoTopographic Databases – , is underway in cooperation with CISIS  (a consortium of Italian Regions).

WFS demo 

As a demonstration of the functionalities of IDMT a DBS has been defined and the generated Script files have been used to create an INSPIRE DB and to install a WFS service at the following address:

http: wfs.spatialdbgroup .polimi. it/deegree-webservices-3.3.9/services

The DBS definition is included in the IDMT_937 download. It has the following parameters:

• Name: DBSdemo
• CRS : 3003
• Dimension: 3D
• lmplementation Model: SQL for GML
• Selected Feature Types: Network, TransportNetwork, RoadLink, RoadNode, RoadLinkSequence, RoadWidth and VerticalPosition

The INSPIRE Database has been loaded with production data containing about 80,000 RoadLinks and 30,000 RoadNodes.

In order to use the service it is necessary to write the necessary queries and submit them with a Browser. Some example queries have been proposed as demonstrations in the following links (if a link starts but does not return a result, copy link in your browser and execute – we have tested Edge and Firefox):

• Selection of all Road Links (gml v.2.1.2)

http://wfs.spatialdbgroup.polimi.it/deegree-webservices-3.3.9/services?SERVICE=WFS&VERSION=1.1.0&REQUEST=GetFeature&OUTPUTFORMAT=text%2Fxml%3B+subtype%3Dgml%2F2.1.2&TRAVERSEXLINKDEPTH=0&TypeName=RoadLink

• Selection of all Road Nodes (gml v.3.2.1):

http://wfs.spatialdbgroup.polimi.it/deegree-webservices-3.3.9/services?SERVICE=WFS&VERSION=1.1.0&REQUEST=GetFeature&OUTPUTFORMAT=text%2Fxml%3B+subtype%3Dgml%2F3.2.1&TRAVERSEXLINKDEPTH=0&TypeName=RoadNode

• Selection of the Road Nodes in a BBOX (gml 2.1.2)

http://wfs.spatialdbgroup.polimi.it/deegree-webservices-3.3.9/services?SERVICE=WFS&VERSION=1.1.0&REQUEST=GetFeature&OUTPUTFORMAT=text%2Fxml%3B+subtype%3Dgml%2F2.1.2&TRAVERSEXLINKDEPTH=0&BBOX=1686000,5026000,1705000,5035000&TypeName=RoadNode

Unfortunately, as far as we know current GIS clients are not able to deal with the complex INSPIRE GML encoding. However we have verified for example QGIS is able to read and display the RoadLinks and RoadNodes obtained from the above queries, although it loses all information of the associations between features.

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