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SemanticSTEP Viewer

SemanticSTEP Viewer - listing top named graphs Click to enlarge

SemanticSTEP Viewer (SSV) is the user interface (frontend) to access SRDB and work with ontologies. It is a sample implementation of how to access SRDB for semantic data. SSV allows adding, searching and viewing SemanticSTEP ontologies (named graphs).

Sample viewer

A sample SemanticSTEP Viewer installation is running on top of our sample SRDB installation. The SSV can be accessed at http://srdb.s-ten.net/SSV.

Technology

SSV is a web browser application collected into a Java servlet on some web server. This frontend uses HTML, XML Stylesheet Transformations (XSLT) and JavaScript to provide the user interface. The server side of SSV serves as a file provider and performs minimal processing (applies the SSV template).

SSV relies on SRDB for data retrieval. The application is able to handle SemanticSTEP named graph ontologies.

SemanticSTEP Viewer architecture

SemanticSTEP Viewer architecture

Features

SemanticSTEP Viewer - named graph overview Click to enlarge

To examine a sample SSV installation, visit http://srdb.s-ten.net/SSV. SSV can be deployed to other web servers where a SRDB installation is running.

SSV can be used to view the data stored in the SRDB. Currently it provides such features:

  • Upload named graphs to the SRDB;
  • List all named graphs. A quick link to list all named graphs that are available in the SRDB. A detailed information is available for each named graph by clicking on named graph URL. Note: this quick link is implemented as a predefined SPARQL query to list all named graphs;
  • List top named graphs. A quick link to list top graphs only. Graphs, which are included by other named graph ontologies are excluded from this list. This allows seeing graphs that are entry points into the SRDB data. Note: this quick link is implemented as a predefined SPARQL query to list top named graphs;
  • Search for a simple string. A simple text search functionality for SRDB data. The string can be entered as a regular expression and the maximum number of results can be indicated;
  • Query data using SPARQL. A SPARQL query can be created to find data in the SRDB. The results would be presented similarly to the named graphs list;
  • Create advanced SPARQL queries. Create a SPARQL query and select the output format from a list of Text, RDF, XML or JSON;
  • Show detailed information for a specific named graph.

Presenting named graph information

SemanticSTEP Viewer - aspect view Click to enlarge

Named graph is presented in several views that are defined in XML Stylesheets. Those stylesheets provide a way to view overview, aspects and other information derived from the graph. The named graph overview page can be opened either by following a list from named graph list or by using the Show data functionality.

When a component link in overview page is opened, a new page displays further details about the selected product.

Known issues

Currently SSV allows accessing data from a SRDB, which is hosted on the same domain as the SSV. For example, if SRDB is running at http://srdb.s-ten.net, then SSV also must be installed at http://srdb.s-ten.net. This issue is caused by the security requirements of the web browsers. There are ways to configure a web browser to ignore this limitation by configuring them for the specific SSV installation or using signed JavaScript packages. However, this solution is specific to a web browser and may be an obstacle for an easy use of SSV.

XSLT transformations used for graph ontology visualization create a lot of constraints for SSV features and performance. Further development should focus more on using JavaScript than XSLT to overcome these weaknesses.

As SSV uses the webserver minimally, this adds flexibility on deploying it. However, to get rid of security and performance issues, more server side processing could also be added to the SSV.