ontologies in data and application integration – an update

Ontologies in Data and Ontologies in Data and Application Integration – an Application Integration – an

UpdateUpdateKai Lin

Bertram Ludäscher

Knowledge-Based Information Systems Lab

Data and Knowledge Systems (DAKS)San Diego Supercomputer CenterUniversity of California San Diego

http://www.geongrid.org

http://www.sdsc.edu/

GEON PI Meeting, VTech March 21—23rd 2004 2

Outline

1. Motivation

2. Ontology Cheat Sheet

3. Ontology-enabled Prototypes and Tools

4. Data & Service Registration (Structural + Semantic)

5. Scientific Workflows


Ontology Cheat Sheet (1/2)

• What is an ontology? An ontology usually … – specifies a theoryspecifies a theory (a set of modelsmodels) by …– definingdefining and relatingrelating …– conceptsconcepts representing features of a domain of interest

• Also an overloaded (sometimes sloppy) term for:– Controlled vocabularies– Database schema (relational, XML, …)– Conceptual schema (ER, UML, … )– Thesauri (synonyms, broader term/narrower term)– Taxonomies– Informal/semi-formal representations

• “Concept spaces”, “concept maps”• Labeled graphs / semantic networks (RDF)

– Formal ontologies, e.g., in [Description] Logic (OWL)• “formalization of a specification” constrains possible interpretation of terms


A Multi-Hierarchical Rock Classification “Ontology” (GSC)

Composition

Genesis

Fabric

Texture


Ontology Cheat Sheet (2/2)

• What are ontologies used for? – Conceptual models of a domain or application,

(communication means, system design, …)– Classification of …

• concepts (taxonomy) and • data/object instances through classes

– Analysis of ontologies e.g.• Graph queries (reachability, path queries, …)• Reasoning (concept subsumption, consistency checking, …)

– Targets for semantic data registration– Conceptual indexes and views for

• searching,• browsing, • querying, and • integration of registered data

Application Example: Geologic Map Integration

domainknowledge

domainknowledge

Knowledge r

epresentatio

n

Ontologies!?

NevadaNevada

Geoscientists + Computer Scientists Igneous Geoinformaticists+/- Energy

GEON Metamorphism Equation:

+/- a few hundred million years


Geologic Map Integration in the Portal

• After registering datasets, ontologies (here: “classes”), and an application (“OMI”), the datasets can be searched and displayed in an integrated way.


Concept-Based Queries and Analysis

• After registering a source with one or more ontologies, concept-based queries and analysis can be launched

• Here: light-weight client-side processing (SVG)


Ontologies and Data Management

• Where do ontologies fit within data management architectures?

• Several answers, specifically:– An ontology is similar to a schema or conceptual model if

one exists, but is– Developed independently of a particular application– Probably given in a different language– Inherently more general– Usually not a very good schema (weak structure)


Ontologies and Data Management( watch out for Semantic Data Registration later)

Schema Schema Schema Schema

ConceptualModel

ConceptualModel

Ontology

Data

Metadata

DesignArtifact

use concepts from(explicitly or implicitly)


Creating and Sharing Concept Maps (here: Seismology concept map & Cmap

tool)

• Lock up scientists for 2+ days• Add CS/KRDB types• Create concept maps• Refine• Iterate from napkin drawings, to

concept maps, to ontologies


Graph (RDF) Queries on Ontologies

visualisation

RQL Query:Show all “products”

Query Results


Community-Based Ontology Development

• Draft of a geochemistry ontology developed by scientists

Current concept maps and emerging ontologies:1. Igneous Rocks/Plutons2. Seismology3. Geochemistry


Protégé (… not so ezOWL yet…)


Sparrow (a poor man’s OWL tool …)

Simple ASCII-based RDF and OWL entry and manipulation

Semantic Data Registration(joint work w/ Shawn Bowers)


What is Data/Ontology/… Registration?• A A mechanismmechanism by which by which data sources, data sources,

ontologies, services,ontologies, services, … …

• … … are are publishedpublished in a repository/registryin a repository/registry

• for the purpose of “smart” for the purpose of “smart” discoverydiscovery, , queryingquerying, , integrationintegration


Things to Register

• Data files (individual files)– Shapefile as a blob (+ file type)

• Collections (of files; nested; eg satellite data)

• Databases (has schema and can be queried)– Shapefile with schema registered

• Ontologies• Services (web + grid services)• Other/external applications


Connecting Datasets to Ontologies

Date Site Transect SP_Code Count 2000-09-08 CARP 1 CRGI 0 2000-09-08 CARP 4 LOCH 0 2000-09-08 CARP 7 MUCA 1 2000-09-22 NAPL 7 LOCH 1 2000-09-18 NAPL 1 PAPA 5 2000-09-28 BULL 1 CYOS 57


DataCollectionEventMeasurement

MeasurementContextMeasurableItem

SpeciesCountSpeciesAbundance

AbundanceCollectionEventLocation

LTERSiteSBLTERSite

{naples,…}

⊑ contains.Measurement⊑ measureOf.MeasurableItem ⊓ hasContext.MeasurementContext

⊑ hasTime.DateTime ⊓ hasLocation.Location ⊑ hasUnit.Unit ⊓ hasValue.UnitValue ⊑ MeasurableItem ⊓ hasSpecies.Species ⊓ hasUnit.RatioUnit

… ⊑ Measurement ⊓ measureOf.SpeciesCount ⊑ DataCollectionEvent ⊓ contains.SpeciesAbundance ⊑ position.Coordinate ⊑ Location ⊑ LTERSite ⊓ position.SBLTERCoordinate ⊑ SBLTERSite

How can we “register”the dataset to concepts in the Ontology?

Ontology (snippet)

Dataset


Step1: Selecting Relevant Concepts



Concepts from an Ontology

Dataset

• DataCollectionEvent• AbundanceCollectionEvent

• Measurement• Abundance

• SpeciesAbundance

• MeasurableItem• SpeciesCount

• Location• LTERSite

• SBLTERSite• naples

• Species• …

• MeasurementContext• …


Step1: Selecting Relevant Concepts



Concepts from an Ontology

Dataset







• Species• …



Step2: Generate Object ModelConcepts from an Ontology

AbundanceCollection Event

SpeciesAbundance

containsSpeciesCount

measureOf

Species

hasSpecies

RatioUnit

hasUnit

RatioValue

hasValue

DateTime SBLTERSite

hasTime hasLoc







• Species• …



Applications of Semantic Registration• Mentioned before:

– Smart data discovery, integration etc.

• New application:– Generating data transformation semi-

automatically for chaining together computational services


Problem: Service Reusability

• Unless “designed to fit,” independent services are structurally incompatible

• Generally, the source output type will not be a subtype of the target input type

SourceServiceSourceService

TargetServiceTargetService

Ps Pt

StructuralType Pt

StructuralType Pt

StructuralType Ps

StructuralType Ps

Desired Connection

Incompatible

(⋠)


Service Reusability

• A data transformation mapping () is required to connect the services … artificially creating subtype compatibility

• If such a exists, the services are “structurally feasible”



Ps Pt

StructuralType Pt

StructuralType Pt

StructuralType Ps

StructuralType Ps

Desired Connection

Incompatible

(⋠)

(Ps)(Ps) (≺)


Service Reusability

• Idea: – annotate services with semantic types (concept

expressions) primarily for discovery of services



Ps Pt

Ontologies (OWL)Ontologies (OWL)

SemanticType Ps

SemanticType Ps

SemanticType Pt

SemanticType Pt

Desired Connection

Compatible ( )⊑


Service Reusability

• Services can be semantically compatible, but structurally incompatible



Ps Pt

SemanticType Ps

SemanticType Ps

SemanticType Pt

SemanticType Pt

StructuralType Pt

StructuralType Pt

StructuralType Ps

StructuralType Ps

Desired Connection

Incompatible

Compatible

(⋠)

(⊑)

(Ps)(Ps) (≺)



The Ontology-Driven Framework (work w/ Shawn Bowers, SEEK)



Ps Pt

SemanticType Ps

SemanticType Ps

SemanticType Pt

SemanticType Pt

StructuralType Pt

StructuralType Pt

StructuralType Ps

StructuralType Ps

Desired Connection

Compatible ( )⊑

RegistrationMapping (Output)

RegistrationMapping (Input)

CorrespondenceCorrespondence

Generate (Ps)(Ps)


Transformation


Example Generated Data Transformation (in XQuery)

• Based on the structural correspondences and certain assumptions, we derive the transformation query:

<cohortTable> { for $s in /population/sample return <measurement> { for $c in $s/meas/cnt return <obs>{$c/text()}</obs> } { for $l in $s/lsp return <phase>{$l/text()}</phase> } </measurement> }</cohortTable>

Scientific Workflows(Efrat Jaeger et al.)


Reverse Engineering a Scientific Workflow using the KEPLER Tool (Efrat Jaeger)


A Scientific Workflow in Kepler

Extract mineral composition for row Id.

Igneous Rock Diagrams information.

Rock Name.


Reverse-Engineered the Geological Map Integration in Kepler


DataMapper Sub-Workflow


Result launched via the BrowserUI actor


KEPLER and YOU

• Kepler …– is a community-based, cross-project,

open source collaboration– for “minute made” application

integration– using web (grid) services as basic

building blocks– has a joint CVS repository, mailing

lists, web site, …– is gaining momentum thanks to

contributors and contributions• BSD-style license allows commercial

spin-offs – a pre-packaged, shrink-wrapped

version (“Kepler-to-GO”) coming soon to a place near you…

F I N – Questions?

Additional Material


The KEPLER GUI (Vergil from Ptolemy II)

Drag and drop utilities, director and actor libraries.


Running the workflow


Distributed Workflows in KEPLER

• Web and Grid Service plug-ins– WSDL– ProxyInit, GlobusGridJob, GridFTP, DataAccessWizard– SRB– SSH, SCP

• Web Service Harvester– Imports all the operations of a specific WS (or of all the WSs in a UDDI repository) as Kepler actors

• XSLT and XQuery transformers to link non-fitting services together

• Web Service Deployment (…ongoing work…)


A Generic Web Service Actor

Given a WSDL and the name of an operation of a web service, dynamically customizes itself to implement and execute that method.

Configure - select service operation


Set Parameters and Commit

Set parameters and commit


WS Actor after Instantiation


Web Service Harvester

• Imports the web services in a repository into the actor library.• Has the capability to search for web services based on a keyword.


Composing 3rd-Party WSs

Output of previousweb service

User interaction &Transformations

Input of next web service

Providing DB Access through Kepler

• Database connection actor: – Opening a database connection and passing it to all actors

accessing this database.

• Database query actor:– A generic actor that queries a database and provides its

result.

• DBConnection type and DBConnectionToken:– A new IOPort type and a token to distinguish a database

connection from any general type.

Database Connection Actor

OpenDBConnection actor:

• Input: database connection information.• Output: A DBConnectionToken, a reference

to a database connection instance, through a DBConnection output port.

Database Query Actor

Database Query actor:

Input: A query string (SQL) and a database connection reference.

Parameters: output type – XML, Record or String. output each row separately or all at once.

Process: Execute query. Produce results according to parameters.

Querying Example


Resource Description Framework (RDF)

Simple data model that consists of– Resources (uniquely identified via URIs)– Properties – Values (resources or character strings)

Data organized into triples (subject, property, value)

SonomaRegion CaliforniaRegionlocatedIn

Subject(Resource)

Value(Resource)

Property(Resource)

locatedIn(SonomaRegion, California)


RDF Schema

Adds a set of pre-defined properties to define classes and properties

Allows instances to be connected to classes

Sub-class and sub-property (is-a) relationships

SonomaRegion CaliforniaRegionlocatedIn

Region

rdf:type rdf:type

locatedInRegion is a classlocatedIn is a propertylocatedIn connects Regions


OWL

Adds additional pre-defined properties to further constrain an ontology(See http://www.w3.org/TR/owl-guide/)

Note, RDF(S) and OWL use XMLSome graphic tools exist (e.g., Protégé)

<owl:Class rdf:ID="Vintage"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty rdf:resource="#hasVintageYear"/> <owl:cardinality>1</owl:cardinality> </owl:Restriction> </rdfs:subClassOf> </owl:Class>

A Vintage is a class that is a subclass of an unnamed class whose instances always have

one hasVintageYear property.

Note the uglified XML syntax…The good news: meant for

parsers, not humans!

ontologies in data and application integration – an update

Documents

nevadafoobargeon pi

conceptbased queries

application integration

data managementwhere

reasoning concept subsumption

data management architectures

conceptual schema er

path queries