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Engineering a Replay Application Based on RDF and OWL

Engineering a Replay Application Based on RDF and OWL. Chris Greenhalgh , Andy French, Jan Humble, Paul Tennent School of Computer Science, University of Nottingham email: {cmg, apf, jch, pxt}@cs.nott.ac.uk. Content. Introduction to DRS Persistence and state in DRS

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Engineering a Replay Application Based on RDF and OWL

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  1. Engineering a Replay Application Based on RDF and OWL Chris Greenhalgh, Andy French, Jan Humble, Paul Tennent School of Computer Science, University of Nottinghamemail: {cmg, apf, jch, pxt}@cs.nott.ac.uk

  2. Content • Introduction to DRS • Persistence and state in DRS • Using RDF and OWL within DRS • Performance strategies and issues • Conclusions and Future Work

  3. Introduction to DRS

  4. Persistence and State in DRS DRS GUI Media & log files JENA RDF Models File-backed HSQL DBs Index Project(s) RDBMS

  5. Persistence and State in DRS Operational (meta)data, Annotations, Other metadata Video, Audio, Images, Documents Highly structured log file events Media & log files JENA RDF Models File-backed HSQL DBs Index Project(s)

  6. OWL Ontologies • digitalrecord.owl • core digital record, • E.g. Media (files), Projects, “Analyses”, People, Annotations, Times, Timelines, Activities • replaytool2.owl • DRS configuration and security, • guiconfiguration.owl • new GUI configuration options, and • logfileworkbench.owl • for working with system log files and databases • E.g. databases, representations of time, table column types

  7. Implementation: Ontology wrapper classes • Wrappergen tool • Reads ontology • Generates Java: • Interface hierarchy (multiple inheritance) • JENA & JavaBean implementation hierarchies (single inheritance) • Type-safe Java programming • Limited query support • Still use SPARQL • Open Source (DRS CVS)

  8. Performance strategies (1) • Horses for courses – RDF, files and databases • For (meta)data, media and processed log-file data/events • Divide and conquer – top-level division into “projects” • Separate JENA models for each • Deliberately limited inference • In (separate) ontology model only • RDFS entailments only • Requires explicit expansion of queries, e.g. instances of a class (including instances of subclasses)

  9. API Monitor model In-memory model Save/exit Statements added/removed JDBC Persistent model RDB Performance strategies (2) • Model cacheing • JENA Monitor model tracks changes • Incremental changes flushed by explicit user action (save/close) • Possible building block for undo/redo

  10. Performance issues • Choice of RDBMS with JENA • MySQL • Requires installation and configuration • 25ms/statement insert with duplicate checking • 0.75ms/statement insert without duplicate checking • HSQLDB • Runs embedded and file-backed – no installation • 0.22ms/statement insert with duplicate checking, 2170 statements • 1.22ms/statement insert with duplicate checking, 13000 statements • 0.33ms/statement insert without duplicate checking, 15000 statements

  11. Conclusions and Future Work • Effective combination of RDF, files and databases • Various performance strategies • Not yet validated with very large projects… • Reasonable software development support • Wrapper classes, JENA API, SPARQL queries • Beginnings of ontology-driven interface elements • Big usability challenges • Work-group server support – in progress • CVS-like RDF check-out/check-in approach for intermittently networked collaboration • Open Source release, ongoing development/support

  12. Acknowledgements • This work was supported by the ESRC through the grant “Understanding New Forms of Digital Record for E-Social Science” (the DReSS node of the NCeSS) and by the EPSRC through grant EP/C010078/1, “Semantic Media - Pervasive Annotation for e-Research” and the EQUATOR IRC, grant GR/N15986/01. • With thanks to our collaborators in those projects. • With thanks to the Thrill project.

  13. Release 1: http://thedrs.sourceforge.net Announcingthe Digital Replay SystemRelease 1 Supports the coordinated replay, annotation and analysis of combinations of video, audio, transcripts, images and system log files. Multiple Videos Transcript Log data Timeline Free and Open Source – http://thedrs.sourceforge.net Requires Windows or Mac OSX, Java 1.5+ and Apple QuickTime. DReSS

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