1. * RDF from the Java Perspective

2. 2 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Three-Step Recipe Create RDF metadata in Java. Serialize my RDF to RDF/XML. Interface with the information service? Library support:  Jena (com.hp.hpl.jena.rdf.model)  HttpClient (org.apache.commons.httpclient)

3. 3 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Data Stream Management Collection of metadata  Statistics  Content-Provider  Optimization Use of information service  Metadata storage  Query interface

4. 4 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Data Sources in Data Stream Management: Content-Providers Publish multiple data streams Content-Provider metadata:  ID  Stream metadata  ID  Structural information (DTD)  Frequency

5. 5 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Queries on Metadata Which streams are in general available at content providers? Which streams are availabe at content provider notekemper15.informatik.tu- muenchen.de? Which content providers serve the stream with identifier stream-1? What is the DTD of stream-1 at notekemper15?

6. 6 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl The RDF Model ContentProvider@notekemper15 id stream-1 stream-2 TUM stream stream-2 stream-1 3 11 id frequency dtd

7. 7 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Creating the RDF Model in Java Create Model-Instance Resources  notekemper15 (ContentProvider)  stream-1 (Stream) Properties  dtd, frequency (of streams) Creating Triples (Subject, Predicate, Object)  (notekemper15, stream, stream-1)  (stream-1, dtd, )

8. 8 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Creating the RDF-XML RDFWriter serializes RDF-Model <rdf:RDF xmlns:j.0="http://www.gac-grid.org/namespaces/streaming/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" > TUM stream-2 <!ELEMENT stream (row)*> 3 stream-1 <!ELEMENT strom (row)*> 11

9. 9 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Connecting the Information Service Create new HttpClient Create PutMethod to access Information Service„http://mintaka.aip.de:24000/context/streamin g“ Set content of PutMethod to generated RDF/XML Execute the PutMethod with the HttpClient

10. 10 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl Submit Query to Information Service “Return all Content-Providers and their available streams including stream-ids and Document Type Definitions“ PREFIX stream: PREFIX rdf: SELECT ?cp ?stream ?id ?dtd WHERE { ?cp stream:stream ?stream. ?stream stream:id ?id. ?stream stream:dtd ?dtd. }

11. 11 AstroGrid-D Workshop, Garching 2006-11-14 Tobias Scholl RDF Workshop Thank You for Your Attention! Further Questions?