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Open Source Software for Geodata Harmonisation

http://community.esdi-humboldt.eu

The process of geodata harmonisation should create the possibility to combine data from heterogeneous sources into integrated, consistent and unambiguous information products, in a way that is of no concern to the end-user.

Users shall be enabled to formulate their demand for geospatial data, involving requirements on the format, spatial reference system, data schema or language of the data. Based on a formalised description of the demand, information shall be provided to the user that is directly usable, i.e. that meets the requirements. The aim of this open source project is to provide the software for achieving or at least supporting this vision. The software can be divided into the following main categories: Data Harmonisation Toolkit, Framework for Service Integration, and Processing Components / Transformation Services.

1. Data Harmonisation Toolkit
The data harmonisation toolkit consists of a set of tools with graphical user interfaces that enable users to perform different tasks such as conceptual schema modelling and mapping.

  • The GeoModel Editor is an easy-to-use editor for application experts, aiming at collecting all required information on the geodata. It provides a formal representation of the information on the geodata in order to feed it into a harmonisation process. It uses a “spatial UML”, which uses similar concepts as UML but is strictly restricted to geodata modelling, taking into account all requirements and recommendations of the INSPIRE data specification guidelines.
  • The Alignment Editor is a tool with a rich graphical user interface for defining mappings between concepts in conceptual schemas (e.g. application schemas created with the GeoModel Editor), as well as for defining transformations between attributes of these schemas. The Alignment Editor has several properties which make it stand out from other data transformation definition tools. Among these are the following aspects:
    • Definition of mappings that are independent from concrete data sources;
    • Continuous quality assurance of created mappings;
    • A task-based user interface that makes a complex mapping process manageable and deterministic;
    • Geographic data can be used to interactively visualize and test defined mappings;
    • Documentation of the limitations that a mapping has, e.g. by providing descriptions of known mismatches.

2. Framework for Service Integration
The Framework for Service Integration consists of software components that enable users to publish geodata and to consume geodata via OGC-conformant interfaces, harmonised and transformed to their requirements. It consists of the following services:

  • The Context Service (CS), a service for managing product descriptions for transformation results, users and organisations;
  • The Mediator Service (MS), a harmonisation workflow execution engine that offers transformation, download and view service interfaces for seamless integration with existing environments;
  • The Workflow Design and Construction Service (WDCS), a component for analysing harmonisation needs and for constructing workflows;
  • The Information Grounding Service (IGS), is a catalogue. It provides cascading catalogue functionalities by periodically harvesting external catalogues.
  • The Model Repository (MR), a conceptual schema and mappings repository.

3. Processing Components / Transformation Services
The framework is able to handle processing services that are encapsulated within web services that conform to the OGC Web Processing Service standard or processing services that are directly implemented on the platform on which the Mediator Service is deployed. There are several harmonisation processing components already implemented (or about to be implemented) as part of the open source framework:

  • The Coordinate Transformation Service is a WPS implementation of a service that allows transforming coordinates between various geographic reference systems
  • The Conceptual Schema Transformer is a Web Processing Service (WPS 1.0.0) that is able of applying a schema transformation to a source WFS dataset (Application Schema A) in order to provide a target dataset (Application Schema B). A schema mapping between schema A and schema B has to be defined in order to accomplish the transformation.
  • The Multiple Representation Merger is a Web Processing Service (WPS 1.0.0) that is capable of fusing Features of data sets with a spatial overlap, such as along a common border, where water bodies are part of both data sets.
  • The Edge Matching Service (EMS) is a WPS (1.0.0) implementation of a service that aligns edges and points of vector geometries so that they will be gapless.
  • The Language Transforming Processor enables the language transformation of data sets (attribute name and attribute value transformations). It employs the Language Transformer for translation. The Language Transformer transforms single terms from one language to another. It uses an internal database that holds translations and that can be populated via the interface of the language transformer. Further, it employs the General Multilingual Environmental Thesaurus for retrieving transformations.

The first release of the Open Source Software for Geodata Harmonisation was published in April 2009. The development is continued in the EU-project HUMBOLDT. This open source release is the first major step towards the creation of an Open Source Community for Geodata Harmonisation Software and the HUMBOLDT consortium invites developers to test the design and expandability of the framework. Suggestions and contributions are highly welcome.

The Open Source Software is published under GNU Lesser General Public License version 3 (LGPL v3).

For more details on the Open Source Software for geodata harmonisation, please visit the community website:

http://community.esdi-humboldt.eu/

For more details on the HUMBOLDT project, please visit the project's website:

http://www.esdi-humboldt.eu/home.html

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Last updated 2809 days ago by Eva Klien