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

DReSS

Content

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

DReSS

Introduction to DRS

DReSS

Persistence and State in DRS

RDBMS

JENA RDF ModelsMedia & log files

File-backed HSQL DBsIndex Project(s)

DRS GUI

DReSS

Persistence and State in DRS

JENA RDF ModelsMedia & log files

File-backed HSQL DBsIndex Project(s)

Highly structured log file events

Video, Audio,Images,

Documents

Operational(meta)data,

Annotations, Other metadata

DReSS

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

DReSS

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)

+getResource()+getModel()

«interface»Thing

+getHasMimeType()+setMasMimeType()+isSetHasMimeType()+unsetHasMimeType()+addHasMimeType()+removeHasMimeType()

«interface»Media

«interface»Video

MediaImpl

VideoImpl

ThingImpl

DReSS

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)

DReSS

Performance strategies (2)

Model cacheing– JENA Monitor model tracks

changes– Incremental changes flushed by

explicit user action (save/close)– Possible building block for

undo/redoRDB

Persistent model

Monitor model

In-memory model

Statements added/removed

Save/exit

JDBC

API

DReSS

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

DReSS

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

DReSS

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.

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

TimelineLog data

Transcript