ORDI and wsmo4j Damyan Ognyanov Ontotext Lab, Sirma AI

7 Apr, 2005

ORDI and wsmo4jDamyan Ognyanov

Ontotext Lab, Sirma AI

ORDI and wsmo4j, OM Tools Fair, Grenoble

#2/24

7 Apr, 2005

wsmo4j Introduction

wsmo4j is an open-source project with two parts:• WSMO API – application programming interfaces for

WSMO, which allow for basic manipulation of WSMO descriptions, e.g. creation, exploration, storage, retrieval, parsing, and serialization;

• wsmo4j – a reference implementation of the WSMO API, including a WSML parser and a file-system-based datastore.

• wsmo4j development is led by Ontotext• Delivered as D6.4 within DIP• Based on v.1.0, 20/09/2004, of WSMO


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7 Apr, 2005

wsmo4j Conceptual Grounds

• wsmo4j is fully based on WSMO• ORDI is based on D2.2 of DIP (commented later)

• The presentation first covers wsmo4j as it is • Then comments on the ORDI current status and

design


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7 Apr, 2005

Functionality: wsmo4j packages

• Common: the most general primitives, e.g.: identifiers, literals, variables, and non-functional properties.

• IO: input and output related interfaces. Sub-packages:– Parser: parsing from or serialization to a particular

syntax;– Datastore: basic store and load interfaces;– Locator: resolving physical locators to logical identifiers.

• Ontology: contains ontology-specific interfaces (ontologies, concepts, etc.) Represents the bridge to the OM tools developed within the OMWG. – The package namespace is org.omwg.ontology.*, in

contrast to the other packages of the WSMO API, whose names start with org.wsmo.*.

• Goal, Service, Mediator: WS modelling related interfaces.


#5/24

7 Apr, 2005

wsmo4j Architecture

WSMO StudioSWS Integrated Development

Environment


Environment

Ontology Management Suite


WSMO APIInterface Definitions


WSMO4JReference Implementation


Common & IO

Ontology

Goal Service

Mediator

In-memory Structures

File Datastore

WSML Parser

ORDIOntology Representation

& Data Integration

Reasoner Wrappers

Import/Export Parsers

Repository Wrappers

Data Integration

Versioning

Mapping

Editing and Browsing


#6/24

7 Apr, 2005

Overall Interoperability


Environment


Environment







ORDIOntology Representation

& Data Integration

Repository(Sesame/

YARS)

Reasoner(KAON2)

Other Data-sources


#7/24

7 Apr, 2005

wsmo4j basics

• Naming Conventions: – set*() and get*() for accessing and modifying properties

of a class, which are not collections;– list*(), find*(), add*() and remove*() for accessing a

collection.

• Common Interfaces located in the org.wsmo.common:– Entity – top-level interface;– Identifiable – represents entities that have an identifier;– Identifier – four types: URI references, literals,

anonymous identifiers, variable names;– the interfaces related to non-functional properties,

NFPHolder.


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7 Apr, 2005

Wsmo4j: Helper Interfaces

• Factories:– WSMOFactory interface presents the Factory pattern

responsible for creating instances of all WSMO entities;– create*() methods accept an Identifier parameter for

the entity identifier (in most cases is a URIRef).– The WSMOFactory is created by the Factory class

(which is sort of a meta-factory). Multiple different implementations of the WSMOFactory interface may be created, if desired.

• Containers• Exceptions• Mediatable


#9/24

7 Apr, 2005

wsmo4j: Ontology creation sample (I)

//1. initialise the factory with the wsmo4j provider

HashMap factoryParams = new HashMap();

factoryParams.put(Factory.FACTORY_PROVIDER_CLASS,

"com.ontotext.wsmo4j.common.WSMOFactoryImpl");

//2.get a reference to the WSMO Factory

WSMOFactory wsmoFactory = Factory.getWSMOFactory(factoryParams);

try {

//3. create an ontology

Ontology anOntology = wsmoFactory.createOntology(

wsmoFactory.createURIRef(“…"));

// 3.1 setup a namespace

anOntology.addNamespace("my", “…");

// 3.2 attach some NFPs

anOntology.addNFPValue(NFP.DC_TITLE, "International TTO …");


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7 Apr, 2005

wsmo4j: Ontology creation sample (II)

// 3.3 adds some references to mediators and imported ontologies anOntology.addImportedOntology(wsmoFactory.createURIRef(

"http://www.wsmo.org/ontologies/dateTime"));

anOntology.addNamespace("dt", "http://www.wsmo.../dateTime#");

anOntology.addUsedMediator(wsmoFactory.createURIRef(

"http://www.wsmo.org/owlPersonMediator.wsml"));

//4. add concepts and instances to the ontology

//4.1 define xsd:string to use it as attribute range

Concept XSD_STRING = Factory.getWSMOFactory().createConcept(null,

Factory.getWSMOFactory().

createURIRef("http://www.w3.org/2001/XMLSchema#string"));

//4.2 create the Location concept

URIRef uriL = anOntology.createURIRef("loc", "location");

Concept cLocation = wsmoFactory.createConcept(anOntology, uriL);


#11/24

7 Apr, 2005

wsmo4j: Ontology creation sample (III)

// create the Station concept, with Location as super-concept Concept cStation = wsmoFactory.createConcept(anOntology,

anOntology.createURIRef("my", "station"));

cStation.addSuperConcept(cLocation);

cStation.addNFPValue(NFP.DC_DESCRIPTION, "Train station");

//4.3 add the Code and LocatedIn attributes to Station

Attribute attrCode = cStation.createAttribute(anOntology.createURIRef("code"));

attrCode.setRange(XSD_STRING, false);

attrCode.addNFPValue(NFP.DC_DESCRIPTION, "Code of the station");

Attribute attrLocatedIn = cStation.createAttribute(anOntology.createURIRef("locatedIn"));

attrLocatedIn.setRange(cLocation, true);

…


#12/24

7 Apr, 2005

Performance and Scalability of wsmo4j

• Haven’t been seriously evaluated

• wsmo4j is designed as an client-side/in-process library• the scalability is considered a server side issue to be

handled by ORDI


#13/24

7 Apr, 2005

Current Status and References for wsmo4j

• http://wsmo4J.sourceforge.org– Two sub-projects: WSMO API and WSMO4J– JavaDoc, samples– Maven portal (incl. XRef)

• DIP D6.4 “WSMO API” – mostly the Programmer’s Guide• The latest release is v0.3, 1st of Feb, 2005

– Based on v.1.0, 20/09/2004, of WSMO

• wsmo4j is the reference implementation which includes:– The API and implementation of the representation classes

(what we call in ORDI WSMO-In-Memory)– File-based Datastore– WSML Parser (with serialization)


#14/24

7 Apr, 2005

ORDI Introduction

• Ontology Representation and Data Integration (ORDI)– conceptual framework, presented in D2.2 of DIP.

• Objectives:– Ontology language neutrality;– Integration of databases and other structured data-

sources;– Ontology and data modularization;– Support for heterogeneous reasoners and data-sources

• WSML Core taken as a formal model– Defined as a minimal but sufficient formal framework– Provides a bridge between multiple representation

paradigms (OO, Frames, RDF)


#15/24

7 Apr, 2005

ORDI Implementation Grounds

• The ORDI implementation, is based on WSMO API. • This dependency was introduced in order to make

sure that, “by design”, the web-service related tools (WSMO Studio) and the OMS are interoperable.

• ORDI is not only an OM infrastructure, it supports the management of all the WSMO elements (including WS-related ones)– This means that, for instance, a WS registry, based on

ORDI can easily make queries which consider conditions on both WS (e.g. capabilities) and ontology elements.


#16/24

7 Apr, 2005

ORDI Current Status

• Design and Prototyping• Implementation of repository wrapper (for Sesame)• Mapping of WSML to OWL/RDF• Target to have a first version by June 2005. It does not

cover:– DB integration– Modularization (datasets)

• The rest of the presentation discusses the design of ORDI


#17/24

7 Apr, 2005

Related Syntaxes

• A WSML document in either:– WSML XML syntax or – WSML human readable syntax,

• OWL in RDF: the standard RDF XML syntax. RDF syntaxes different than XML (e.g. NTriples and N3) will also be supported (through the existing RDF parsers).– RDFS subset which is a proper sub-language of OWL DLP

is considered.

• WSMO-RDF: a WSMO/L document serialized according to:– WSMO RDF Schema: an ORDI-specific RDFS/OWL

ontology (meta-schema) derived from the WSML mapping to OWL (D16.1v0.2). It will be similar to the RDFS schema for OWL and dependent on it.


#18/24

7 Apr, 2005

Representations

We distinguish two internal representations of the ontology data:

• WSMO-In-memory: WSMO-API compliant model (e.g. WSMO4J). This representation is not specific for ORDI;

• WSMO-Triples: representation of WSMO elements as RDF triples according to the WSMO RDF Schema. This is an internal representation allowing us to store WSMO (and other data aligned to its model) into a RDF triple repository for efficient query and management. The WSMO- RDF syntax is a serialization of this representation


#19/24

7 Apr, 2005

Design Issues (I)

• Architecture: Java Middleware which allows remote access to Datastores

– The client-side ORDI is an extension of WSMO4J;– The communication between the client and the server over

RMI – The communication style: explicit requests from the client.

Nothing like lazy loading, silent updates and storage.

ORDIServer

ORDIServer

Java Application

ORDI Client

Non-Java Application

WS Access Point

ORDI Client

RMI

SOAP

(in-process)


#20/24

7 Apr, 2005

Design Issues (II)

• Transactions. Transactions are considered, but not covered currently. This design presumes that it will be possible to group (in the standard DB fashion) multiple modification requests to the server within a single transaction. The commit/rollback behavior requires a careful definition.

• Logical Expressions (LE). – WSML-LE are handled by wsmo4j as literals. – Specific interfaces will be provided for plug-in of WSML-

LE parsers, serializers, validators, interpreters, etc. – These interfaces still have to be clarified and defined

within wsmo4j. – The WSML-LE plug-ins will be dependent on wsmo4j (to

get access to the WSMO element definitions).


#21/24

7 Apr, 2005

Tasks (I)

• WSMO-In-Memory serialization to WSML • WSML parsing to WSMO-In-Memory

– Both are already available within WSMO4J for the HR syntax.

• OWL as RDF conversion to WSMO-Triples. To be handled by the OWL2WSMOConverter. This implementation uses an auxiliary triple repository to collect, group and transform the sets of triples that form the definition of each WSMO element.

• WSMO-Triples to WSMO-RDF serialization. Serialization of WSMO documents or separate elements into WSMO-RDF format. Export of WSMO into RDF or OWL independent from the WSMO RDF Schema is not considered.


#22/24

7 Apr, 2005

Tasks (II)

• WSMO-In-Memory to WSMO-Triples. A straightforward generation of WSMO-Triples.

• WSMO-Triples to WSMO-In-Memory. Instantiation of WSMO-In-Memory representation of WSMO elements based on their WSMO-Triple representations.

• Managing WSMO-Triples. A set of several subtasks:– Store WSMO-Triples. Store into the repository a WSMO-

Triples definition of a WSMO element.– Extract WSMO-Triples for an element, given a logical ID. – Compare WSMO-Triple definitions. The simple variant

of this task will only be able to check whether two WSMO-Triple representations of one and the same WSMO element are equivalent. Meant to allow ORDI to know whether there is a real difference introduced to the definition of the element.


#23/24

7 Apr, 2005

ORDI Representations and Modules

WSMO4JWSMO4J

WSMO Tripliser

WSMO Tripliser

MainRepository

Triple Manager

Triple Manager

OWL2WSMO

OWL2WSMO

WSML-HR

WSMO-Triples

WSMO-In-Memory

WSMO-RDF

OWL-RDF


#24/24

7 Apr, 2005

Wsmo4j and ORDI

http://wsmo4j.sourceforge.nethttp://www.omwg.org

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ORDI and wsmo4j Damyan Ognyanov Ontotext Lab, Sirma AI

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