RDF Model Browser

Resource Description Format (RDF) is general purpose metadata standard by W3 Consortium. It is aimed at enabling machines to understand information on the Web. RDF is the basis for even more prominent initiative Semantic Web. More information about RDF can be found here.

RDF Model Browser is a software platform for interactive visualization of RDF models. It is intended to give comprehensive experience with the model using multiple interactive views. Several views are implemented with this release.

The cornerstone is Resource-Property-Resource Tree view. It is hosted in the left pane of the application and provides easy to use hierarchical model layout. Unlike many other graph visualization tools, it represents RDF model graph as a tree. Since graphs are fundamentally different from trees some nodes of the model appear in the tree more than once. A simple layout algorithm is used for user friendly graph to tree mapping. Only resources (not literals) are mapped to the tree view. Full view of a resource including all its literals is available through Resource view.

Resource view is hosted in the right pane of the application and shows resource currently selected in a tree view. This view provides simple HTML visualization of a single resource or a property. In RDF a property is also a resource.

A filter may be applied to Resource-Property-Resource Tree view to screen out properties irrelevant to user. If user wants to focus on a single property the view becomes Resource Tree view. A good example of such a view is object oriented inheritance diagram familiar to most software developers.

Both tree views support inverted view where the tree hierarchy is composed by object rather than by subject. This allows for convenient representation of models which focus on categorization of objects. Object oriented inheritance diagram is once again a good example of a graph where inverted view is more appropriate. Combined with interactive browsing and property selection the choice of forward and inverse hierarchical visualizations gives user a powerful tool for model comprehension. A model can be viewed in a variety of ways and the user may select appropriate visualizations for different parts of the model.

A model can be loaded for visualization either from local file or from url. In both cases model can either replace the one that is already visualized or be added to it. The latter option is useful for visualization of several models together. For instance a model can be visualized together with its ontology.

This release uses in memory representation of RDF models by default. This brings severe limitations on the size of models which can be visualized. If a model is too large the generic out of memory error message will appear. Servlet container settings may be changed to allocate more memory for the application. It is possible to configure RDF Model Browser to use database backed models. See web.xml configuration file and javadoc/source code for details. Still this software is not suitable for visualization of large models.

The software is implemented as Java Servlets 2.3 web application. This allows for easy deployment and integration with other applications. It has been tested with Apache Tomcat and should be compatible with any other J2EE Servlet version 2.3 container. This release uses open source projects:

This product includes software developed by the Apache Software Foundation.

The credits are also given in the application's About screen.

Dima Skvortsov

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