1. DReSS 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

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

3. DReSS Introduction to DRS

4. DReSS Persistence and State in DRS RDBMS JENA RDF ModelsMedia & log files File-backed HSQL DBs IndexProject(s) DRS GUI

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

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

7. DReSS Implementation: Ontology wrapper classes n 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. DReSS Performance strategies (1) n Horses for courses – RDF, files and databases –For (meta)data, media and processed log-file data/events n Divide and conquer – top-level division into “projects” –Separate JENA models for each n 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. DReSS Performance strategies (2) n Model cacheing –JENA Monitor model tracks changes –Incremental changes flushed by explicit user action (save/close) –Possible building block for undo/redo RDB Persistent model Monitor model In-memory model Statements added/removed Save/exit JDBC API

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

12. DReSS Acknowledgements n 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. n With thanks to our collaborators in those projects. n With thanks to the Thrill project.

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