1. 8 Apr, 2005 OWLIM - OWL DLP support within Sesame Damyan Ognyanov Ontotext Lab, Sirma AI

2. OWLIM, OM Tools Fair, Grenoble #2/9 8 Apr, 2005 Introduction OWLIM is an OWL DLP In-Memory SAIL for Sesame 1.1. SAIL = storage and inference layer OWLIM supports partial, forward chaining based, reasoning over OWL DLP. It is open-source It includes a custom RMI factory that enables an application to get direct access to the sail-stack of a repository through RMI. OWLIM is: developed by Ontotext used in SEKT, through the KIM semantic annotation platform A “reference reasoner” for the PROTON upper-level ontology

3. OWLIM, OM Tools Fair, Grenoble #3/9 8 Apr, 2005 Conceptual Grounds Forward-chaining of entilement rules like those used in the RDFS model-theoretic semantics: && => OWL primitives are modeled as: && =>

4. OWLIM, OM Tools Fair, Grenoble #4/9 8 Apr, 2005 Functionality The functionality of Sesame: –Parsing, serialization of RDF (XML, NTriples, N3) –Storage and retrieval –Reasoning –Query Answering (RQL, RDQL, SeRQL) OWL RDF schema supported, including: SymmetricProperty, TransitiveProperty, inverseOf, equivalentClass, equivalentProperty, sameAs, FunctionalProperty, InverseFunctionalProperty

5. OWLIM, OM Tools Fair, Grenoble #5/9 8 Apr, 2005 Persistence Strategy OWLIM “reasons” in-memory, but has a comprehensive persistence and backup strategy Persistence based on N-Triple files: –Number of files can be given as “pre-loaded” –Only one of them can be updated (the “main trunk”) Special attention paid to assure that no loss of information or inconsistency can be caused by an unpredicted interruption The strategy for synchronization of the in-memory representation with the persistent files is configurable The persistence strategy has been extensively tested –It has been used in KIM for a couple of years –It is more reliable than many of the DB-based repositories

6. OWLIM, OM Tools Fair, Grenoble #6/9 8 Apr, 2005 The Architecture: SESAME HTTP HandlerSOAP Handler HTTPHTTP Client1 RMIRMI Client2 SO AP Client3 Admin ModuleQuery ModuleExport Module Storage And Inference Layers (SAIL) DB, Files, … Repository Services Modules SAILs … Remote Access

7. OWLIM, OM Tools Fair, Grenoble #7/9 8 Apr, 2005 Performance and Scalability One of our load tests: –Take KIMO (the PROTON Predecessor) ontology About 300 classes and 100 properties; –The initial KB contained 700k entity descriptions - the KIM World KB was extended with the entities and properties, extracted from the top news for the period 2002-2004. –The test was performing transactions of an addition of 1000 synthetically generated entity descriptions. Average number of statements, per transaction: 12k. Average commit time: 9 sec. –Running on 2xOpteron (1.4Mhz) with 6GB of RAM worth $2000 JDK 1.5 64-bit edition

8. OWLIM, OM Tools Fair, Grenoble #8/9 8 Apr, 2005 Performance and Scalability (II) The results: –Hosted 1.2M entity descriptions: –about 15M explicit statements; –above 30M statements after forward chaining. –1300 statements/second upload and reasoning –Linear growth of time and space required –170 bytes/statement in-memory –N3 storage up to 2.2GB, 147 bytes/statement

9. OWLIM, OM Tools Fair, Grenoble #9/9 8 Apr, 2005 Current Status and References for OWLIM http://www.openrdf.org – the home of Sesame http://www.ontotext.com/downloads/index.html#sesame-sail The distribution contains: –Sources and Binaries –System Documentation Short term plans: –Development related to ORDI – support for WSML Core –Provide full support for OWL DLP