Expertise and RDF Services from Semweb
Semantic Databases – RDF Stores
Semantic data are stored nowadays in RDF stores – semantic databases – and are queried by humans or by programs by means of query languages like SPARQL to get logical connections among several semantic graphs or even among different semantic databases, giving a method to access data and meaning across several data sources.
Semweb supports you during the phases of selecting and integrating your RDF store. Take a look at some of the best RDF stores through their SPARQL endpoints: Bigdata™ (SSL), Stardog (SSL), GraphDB™ (SSL), MarkLogic™, Virtuoso™.
Tutorial: follow the loupe (on top left besides this text in a maximized browser.)
Let yourself go (Notes)
- Choose your semantic database system
- Formulate your SPARQL query in its query field
- Execute the query
- Browse the results
- Use the provided examples
- Select one tab in the gray tab bar below to change / show the SPARQL endpoint panel of one semantic database system (e.g. GraphDB or Bigdata)
- Identify the query field. Each system has a slightly different way to describe it:
- on Bigdata im Unter-Tab "QUERY": take here the biggest input field
- on Stardog: "_Query"
- on GraphDB: "Query"
- on MarkLogic: "Query1" - Please consider setting here the following parameters:
+ Content Source must be on "RDFsamples"
+ Query Type must be on "SPARQL"
- on Virtuoso: "Query Text"
- Press a run/execute button in that panel to execute the SPARQL query:
- on Bigdata im Unter-Tab "QUERY": "Execute"
- on Stardog: "Execute"
- on GraphDB: "Execute"
- on Marklogic: "Run"
- on Virtuoso "Run Query"
- The RDF results are displayed as list of triples. Some systems (Mainly GraphDB) allow you to browse among the results.
- In case you want to use the prepared SPARQL queries - please click on "Examples ...", then copy&paste the query to the query field in the endpoint panel