dean allemang semantic web basics

TopQuadrant in collaboration with Jim Hendler presents: “Getting Ready for the Semantic Web with

TopBraid Suite”

TopQuadrant Semantic Web Technology Training Series

Module I-2:Overview of Semantic Technologies and the

Semantic Web

What is Semantic Technology?What is it good for?

© Copyright 2007-2009 TopQuadrant Inc. Slide 2

The Semantic Wave is NOT one thing … there are differing major streams within it

The Semantic WebW3C Standards for sharing information on a world-wide scaleIntranets vs. Internet

Semantic TechnologyEnhanced knowledge access and searchSemantic InteroperabilityInformation syndication… and so forth


Philosophy of Semantics

What is Semantics = “meaning of meaning”Logical Positivism (with a vengeance!) = “Everything is described by values of properties”Shirky: “Semantic Web is about tautologies. (…and tautologies aren’t interesting)”Intelligent Agents = AI on the web (it’s gotta be smart!)


Semantic Web: Make web content machine-readable!

“The Semantic Web is a vision: the idea of having data on the Web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications.[W3C 2001] ”

“The Semantic Web is an extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work incooperation.” [Tim Berners-Lee et al 2001]


What could the Web do?

Web page interaction –uses people as its medium!


What could the Web do? (cont.)

Can this sort of interactionbecome part of the Web itself?


How could the Web do it?

Built-in by the Webmaster

Agree upon an “interlingua”


What about XML? Doesn’t it support semantics?

HTML gave us formatting tags

XML gave us custom tagsYou get to pick your tags/attributesTags can have “meaning” specific to your application

Many dialects have blossomed

XML and XML Schema became W3C standards

Standard dialects are being developed by many industry groups – XBRL.org, FpML.org, TaxML.org, …

Every large organization has their own XML Schemas


Gartner: All Tied Up with XML: 1999

Unprecedented growth of standard development


Gartner: All Tied Up with XML: 2001

From 2001 through 2004 enterprises spent $3 billion on modeling activities with no return on investment from $ 2 billion of it.


A new Web of terminology

What’s the Interlingua for the Interlingua?

Use the same technology for mapping web pages to terminologyto map terminology to one another


What about people? Don’t they make the world go round?

computers and people…better cooperation

OntologyOntology

Annotated Web Page

Annotated Web Page

Annotated Web Page

Agent

OntologyInternet

Human

Source:, Phil Windridge WSWS (2004)


The Web: The World’s Largest Information System!

How did it get so big? What is special about The Web?


How the Web was Won – The Network Effect

The “Network Effect” –The more participants,the more value in joining

At first, there were few web pagesLittle value in joining in.

But then there were more –more value in joining in

A crowd is better yet!Lots of value in joining in


Features of The Web

Anyone can say Anything about Any topic (AAA)All names are global (so that anyone can refer to them!)

Two people might have different names for the same thing . . . (non-unique naming)

. . . Or the same name for different things!

You never know everything on the web (“Open World”)

This isn’t what we want the web to be, it is how the web is (and how it supports the network effect!)


AAA Slogan -

Anyone

can say Anything

about Any topic


Non-unique naming

“Java”

public String getContextPath() {try {Method getContextPathMethod = delegate.getClass().getMethod("getContextPath", null); //$NON-NLS-1$return (String) getContextPathMethod.invoke(delegate, null);} catch (Exception e) {// ignore}return null;}

“Java”?

Programming language?Hot Beverage?

“Coffee”?


Open World Assumption

There’s always something else over the horizon . . .


Web of Ontologies

The more there are, the easier and more valuable it is to create a new one

Network Effect for Ontologies:

From Tim Berners-Lee, ISWC 2003


Semantic Solutions -Expectations we have encountered

A solution is "Semantic" if it:

X understands the meaning of natural language

X interprets perceptual input and forms usable representations

X computes new statistical analyses of data

X recognizes complex patterns in huge amounts of data

X produces high-quality graphics of complex systems

X replaces an intelligent human in a high-impact task

X has a model of uncertainty in data

X can come to correct conclusions despite faulty input.

Companies provide (some of) these, buttypically as “add-ons” or 3rd party solutionsNot as part of core Semantic offerings


W3C standards for semantic models

W3C Semantic stack is built on XMLXML-based Ontology languages are being developed to support semantic interoperability.

“Semantic Web is stimulating a whole new class of applications at individual, enterprise and web scales”– Eric Miller, W3C, Semantic Technologies for eGOV’2003

www.w3.org/www.w3.org/2001/sw

http://www.w3.org/

http://www.w3.org/

http://www.w3.org/2001/sw

http://www.w3.org/2001/sw


W3C standards evolution

“Layer cake” has been modified a few times…

Significant changes:•Addition of a query language (SPARQL)•RDF not dependent on XML•OWL just one of many possible logic formalisms

Not shown: emergence of n3 serialization (built for triples, unlike XML)


TopBraid Suite”



Semantic Web

Mapping the Semantic Terrain:Standards and Languages from

the W3C


The Tree of Knowledge Technologies

AI Knowledge Representation

Semantic Technology Languages

Content Management Languages

Process Knowledge Languages

Software Modeling Languages


Semantic Web Standards Stack


How Semantic Languages Work

Bring information togetherDraw inferences

OWLRDF

RDFS


What is RDF? Distribution of data

ID Model No. Division Product Line Manufacture

location SKUInStock

1 ZX-3 Manufacturing support Paper machine Sacramento FB3524 23

2 ZX-3P Manufacturing support Paper machine Sacramento KD5243 4

3 ZX-3S Manufacturing support Paper machine Sacramento IL4028 34

4 B-1430 Control Engineering Feedback Line Elizabeth KS4520 23

5 B-1430X Control Engineering Feedback Line Elizabeth CL5934 14

6 B-1431 Control Engineering Active Sensor Seoul KK3945 0

7 DBB-12 Accessories Monitor Hong Kong ND5520 100

8 SP-1234 Safety Safety Valve Cleveland HI4554 4

9 SPX-1234 Safety Safety Valve Cleveland OP5333 14


Distribute by rows?1 ZX-3 Manufacturing

supportPaper machine Sacramento FB3524 23

4 B-1430

Control Engineering

Feedback Line

Elizabeth

KS4520 23

7 DBB-12 Accessories Monitor Hong Kong

ND5520 100

Needs common schema - which column is which?


Distribute by columns?

Division

Manufacturing support



Control Engineering

Control Engineering

Control Engineering

Accessories

Safety

Safety

In Stock

23

4

34

23

14

0

100

4

14

Model No.

ZX-3

ZX-3P

ZX-3S

B-1430

B-1430X

B-1431

DBB-12

SP-1234

SPX-1234

Needs to reference entities – which thing are

we talking about?


Distribute by cells!?

Division

7 Accessories

Needs to reference both schema and entities

Most flexible – can distribute data in any way at all!

Division7 Accessorie

sProduct Line4 Feedback Line

Model1 ZX-3


Distribute by cells!?

URI’s

PredicateDivision

7 Accessories

Subject

Object

•Store, •Index, and •Federate these triples

Triple Store


Representing Data in Graphs

Graph = nodes linked by labeled edges


What is RDF?

RDF (Resource Description Framework) is an infrastructure for:

Encoding,Exchange and Distributing metadata

A “Resource“ is anything that you want to describe

RDF Triple:

Subject

Predicate

Object

RDF Triple:

Subject

Predicate

Object


Why is RDF useful?

After all, can’t we express semantics in XML?

XML allows application-specific tagsSemantic exchange can happen, as long as two parties agree on the use of these tags

XML Represents a tree structure – no indication about what is a description, what denotes an object, what values relate to what objects, etc.

RDF provides a way to integrate structured information from multiple sources


What is RDFS?

RDFS is the schema language for RDFType inferences can be made, based on schema


Why is RDFS useful?

RDFS allows us to talk about classes of instances

It provides inferences, e.g.,

Best Western is a Hotel

(and hence, anything we know about Hotelsapplies to Best Western)

RDFS is in RDF (it’s its own schema language!)


How does it work?

RDF

RDF – the Ultimate Mash-up Language !!

RDF

RDFRDF


A little RDF(S) goes a long way

gov: EPA

gov: department

gov: agency

gov: body

A model of government agencies and departments. Such models are called Ontologies.

brm: Business Area brm: Line Of Business

brm: subfunction

brm:Resource Mgmt

brm: s2citizens brm:Energy

eGOV: capabilityeGOV: Standard

eGOV:Service SpeceGOV: Remote Reporting

eGOV: web service

eGovOS: project

gov: FERCgov: DoE


Ontologies are the means to separate “what is common” from “what is different”

Semantic map: Connecting silo domains

From Tim Berners-Lee, ISWC 2003


OWL (formerly DAML+OIL)

What is OWL?

The “Web Ontology Language”W3C Standard

EU (various)DARPA

DAML

DAML+OIL

OIL

OWL

RDF

W3C

Became a Recommendation in February 2004


OWL can specify rich relationships: equivalence, inverse, unique, …


What is OWL good for?

OWL provides a flexible way to talk about sets of resources,

e.g., “All planets around the sun”, “The wives of Henry VIII”, “People who have visited Japan”, “Incidents of SIDS in which the mother is related to someone with epilepsy”

A powerful way to relate information “people who have flown to Japan have been to Japan”, “a person with epilepsy has a neurological disorder”, “planets are astronomical bodies”

Provides a robust way to re-use informationEven if I didn’t expect someone to be interested in the planets around the sun when I built my database, you can define this set and draw conclusions about it (e.g., “there are 9 of them”)


SPARQL

SPARQL Protocol and RDF Query Language

Query Language (like SQL is for databases, XQuery is for XML, etc.)

Extracts information from a graph using pattern matching

“Four-star lodging in New York”


Find data in a graph


TopBraid Suite”



Semantic Web

Comparing Semantic with

Conventional Technologies


Semantic Technology, RDBMs and Object Models

In this session we will compare Semantic Technology with

Relational Database and Object Oriented Technology

We will use as an example a simple application for managing and tracking medical equipment

application will be asked to find an address compare semantic and relational database approaches

We will then identify key differences and similarities between semantic and object models


Semantic and OO Technologies

Comparing Semantic Technology (ST)

and

Object Oriented (OO) Technology


Differing Intents of Semantic and Object Models

Object ModelA specification of how a set of entities can encapsulate data and invoke behaviors on one anotherThe intent of the model is to provide realizable software where object behaviors become fragments of code

Semantic Model (Ontology)A specification of what is known in a region of interestIntent is to maintain consistency between what is known about a domain in general (expertise) and what is observed about a situation (data)


Specification (OO) vs. Knowledge Discovery (ST)

OO: In an Object Model class membership and hierarchy are specified

Classes are defined and express ‘constraints’ on the instances (individuals) that belong to classes

ST: An Ontology model can serve either as a specification of class membership or as a means of knowledge discovery

Sets of properties associated with individuals (instances) may allow them to be viewed as members of several classes at the same timeClass membership is dynamic and depends on the value of the propertiesIn OWL, classes are computed based on assertions about the individuals that might belong to one or more classes


(ST) In OWL, Classes are inferred or computed

OWL classes are interpreted as sets that contain individuals

A class is not a kind of template as in OO technologyIn OWL, classes are built up of descriptions that specify the conditions that must be satisfied by an individual to be a member of the class

Subclasses are subsets of their parent classes.

Superclass-subclass relationships can be computed automatically by a reasoner


OO Systems Define Acceptable Expectations for Instances of Classes and Subclasses

Information Given

What can you do?

PW1729.list_tests(..)

This call must be valid.(and is done like it is for all Medical Equipment, unless stated otherwise)

method list_tests

extends Medical Equipment

Instance ClassPW1729 X-Ray Machine

Medical Equipment Class

X-Ray Machine Class

Instances

Relationships in the model determine what can be done, and what it means to do it.


Properties (ST) vs. Attributes and Relations (OO)

OWL Properties represent relations between two individuals (Not classes)

OWL Property types:

Object Properties link an individual to an individual

Datatype Properties link an individual to simple values• integers, floats, strings, booleans, and so forth• an XML Schema Datatype primitive value or an RDF literal

Those with OO experience/expertise must overcome the typical pre-conception that properties belong to the class!


Properties are first-class constructsThis allows relationships between Properties

hasParent

hasMother hasFather

This is not a class diagram!

In contrast to most OO paradigms, where properties are “owned” or “contained in” Classes

… and for other modelers to reuse properties

dc:creator

my:author

“wherever I use the property ‘author’, tell the world that they can read ‘dc:creator’”

This allows relationships between Properties


In OWL, Properties may have Sub Properties

It is possible to form hierarchies of properties (these are not Class hierarchies)

The rdfs:subPropertyOf construct allows relationships to be abstracted up the sub-property tree.


Properties may have Additional Characteristics

OWL allows the meaning of properties to be enriched through the use of property descriptions:

Sub-property: Relation between properties, that the pairs related byone property are included in the other.

Domain and Range: Descriptions of a property that determines class membership of individuals related by that property.

Inverse: Description of a property that exchanges the Subject and Object in their respective relationship in another property that it is an inverse-of.

Transitive: Chains of relationships collapse into a single relationship.

Symmetric: Description of a property that makes it a self-inverse property

Functional and Inverse Functional

…


What does it mean to be a subclass in OWL?

In OWL, subclass means necessary implication

If A is a subclass of B, then ALL instances of A are instances of B, without exception.

If something is an A, then this implies that it is also a B

OWL allows the use of class expressions in place of named classes

restrictions describe an unnamed set that could contain some individualsthese are anonymous, computed classes

Properties are used to define and describe ClassesProperties are used to create restrictions. Restrictions are used to restrict the individuals that belong to a class. When you define a restriction, it is the property that give rise to the class


Class Expressions and (Multiple) Inheritance

Semantic Web Classes are (logically) sets, so you can do set logic on them:

Parent

Person

Female Male

Mother ∩

“A ‘Mother’ is a ‘Female’ who is also a ‘Parent’”


(ST) Run-time vs. (OO) Design time semantics

In semantic systems, ontologies are run-timemodels

There is no separation between the model and its technical implementation

The model (ontology) is the OWL code

Semantic web technology Model-driven applications

vs.OO technology Model-developed applications


OO Development – Progressive Design and Transformation of Classes into Code

Requirements

Concepts

VOPOS or CRC CRC(ST) No behavior is described anywhere –only inferencing

Design ObjectsAnalysis Objects

Class CodeUse Cases

Method CodeScenarios

ExpectedBehavior

Object Responsibilities(public interface)

Object Services(signatures)

Method Code

Natural LanguageContract ValidationObject DiscoveryHuman Effort

RefactoringAdd SignaturesAdapt to ConstraintsPick Mechanisms

Write code that fulfillsthe defined signatures, Adding private/helper Methods as needed


Summary Table: Understanding the “Lingo”

OO Term Object Technology Semantic Technology ST Term

Class A “Factory for instances”Definition of behavior (methods, values). Defines all the attributes and associations.

Definition of a set of individuals. Uses open world approach – defines some, but not necessarily all possible properties of its members.

Class

Instance Member of one direct class, responds to all methods defined in the class

Member of one or more classes, as determined by the instance property values and class definition

Individual or Instance

Attribute Data encapsulated with an instance. Defined only for the members of the class

Data describing an individual (or instance). Defined globally.

DatatypeProperty

Association Reference pointer from one object instance to another. Defined only for the members of the class

Reference from one RDF resource to another. Defined globally.

ObjectProperty

Inheritance Methods and properties inherit down

Domains and ranges inherits up. OWL constraints inherit down.

Inference


Semantic Web – OO Gotchas!

In the Semantic Web, you infer the class of an object.

The class of an object can change:over timewith what you know/believewith whom you trust

Properties are first-class objects (independent of classes!)Properties form hierarchies as well as classes

No behavior is described anywhere – only inferencing

Multiple set membership is commonplaceNo OO inheritance


OWL / RDFS Preview (for Comparison)

owl:inverseOf ‘child inverseOf parent’Elizabeth has child Charles,

therefore Charles has parent Elizabeth

owl:transitivePropertyElizabeth has descendant Charles, Charles has descendant Andrew, therefore Elizabeth has descendant Andrew

rdfs:subPropertyOf ‘child subPropertyOf descendant’

Elizabeth has child Charles,therefore has descendant Charles


Semantic vs Relational

Comparing Semantic Technology

and

Relational Database Technology


Data in a spreadsheet

Person Company

Melli Annamalai Oracle

Xavier Lopez Oracle

Dean Allemang TopQuadrant

Mike Uschold Boeing

Ora Lassila Nokia


Same data in a relational database

ID Name

1 Melli Annamalai

2 Xavier Lopez

3 Dean Allemang

4 Mike Uschold

5 Ora Lassila

ID Name

1 Oracle

2 TopQuadrant

3 Boeing

4 Nokia

1 12 13 24 35 4

Give each entity a number (a ‘key’) so you have an unambiguous

way to talk about it.

Give each entity a number (a ‘key’) so you have an unambiguous

way to talk about it.

Express relationships by

associating these numbers together in another table.

Express relationships by

associating these numbers together in another table.

Company Table

Person Table

Works For


Same data in a relational database

Works For Company TablePerson Table

ID Name

1 Melli Annamalai

2 Xavier Lopez

3 Dean Allemang

4 Mike Uschold

5 Ora Lassila

ID Name1 Oracle2 TopQuadrant3 Boeing4 Nokia

1 12 13 24 35 4

CountryBased in

ID Name1 USA

2 Finland

1 12 13 14 2


Suppose (as a simplification) that we know that people live in the country where their employer is based.

Query: List all the people and the countries where they live

SELECT p.name, s.name

FROM employment.person p,

employment.company c,

employment.country s,

employment.basedIn bi,

employment.worksFor wf

WHERE

wf.person = p.id AND

wf.company = c.id AND

bi.company = c.id AND

bi.country = s.id ;

Person p works for company c


It is the ‘person’ field of the worksFor table that

corresponds to the person

It is the ‘company’ field of the worksFor table that

corresponds to the company


Same data in a graphMelli Annimalai

Xavier Lopez

Ora Lassila

TopQuadrant

Boeing

Nokia

label

Oracle

USA

Dean Allemang

Finland

Mike Uschold

worksFor (person, company)basedIn (company, country)


Suppose (as a simplification) that we know that people live in the country where their employer is based.

Query: List all the people and the countries where they live

SELECT ?pname ?sname

WHERE

{ ?p :worksFor ?c.

?c :basedIn ?s.

?p rdfs:label ?pname .

?s rdfs?label ?sname .}



It is the ‘person’ field of the worksFor table that

corresponds to the person

The ?p that :worksFor something is a Person

(in the schema)


RDFS and OWL are about Rich Relationships in Data

Information Given

X-Ray Machine located in Room A2003Room A2003 located in ATA Building

Relationship Model

X-Ray Machine located in ATA Building

Information Inferred

QuestionWhere is the X-Ray Machine located?

AnswerIn ATA Building

Where are the relationships?

“located in” is a transitiveProperty

Relationships are explicit in the model and directly available to applications!


OWL has many Build-in Functions for modeling Relationships

Information Given

X-Ray Machine stored in Room A2003Room A2003 located in ATA Building

“located in” is a transitiveProperty“stored in” is a subPropertyOf “located in”

X-Ray Machine located in Room 2003X-Ray Machine located in ATA Building




Still works!Also inverse, functional, local contextual constraints, …

Relationship Model


Getting the same result with a relational database

ID Equipment NameIDQ X-Ray Machine

Room Building A2003 ATA Building

Room_ID EQ_IDA2003 IDQ

Equipment Table

Building Table

Room_Equipment Table



Develop a QuerySELECT Building

FROM Equipment Table, Building Table, Room_Equipment Table

WHERE Equipment Name = “X-Ray Machine” and ID = EQ_ID and Room = Room_ID

Relationships are in documents and in collective memories -not available to applications!

Where are the relationships?

Data Definition Statements? Applications do not use them, they are not descriptive and their scope is a single database

Data Dictionary? Data Registry? They are for human, not computer use


Change happens…

X-Ray Machine located in Room A2003Room A2003 part of Dr Smith’s OfficeDr. Smith’s Office located in ATA Building

“located in” is a transitiveProperty“part of” is a subPropertyOf “located in”

Room A2003 located inDr. Smith’s Office

Room A2003 located in ATA Building

X-Ray Machine located in ATA Building




Relationship Model

Room A2003 located in ATA Building

new

Information Given


Accommodating change with RDB requires database changes AND new queries

Equipment Table


Room Building A2003 ATA Building

Room_ID EQ_ID A2003 IDQ

Equipment Table

Building Table



Business Name ID Building Dr Smith MDS ATA Building

Room ID Equipment IDA2003 IDQ

Room_ID Bus_IDA2003 MDS

Building Table


Room_Business Table


Accommodating change with RDB requires database changes AND new queries

Equipment Table

Using the same query:


SELECT Building

FROM Equipment Table, Building Table, Room_Equipment Table

WHERE Equipment Name = “X-Ray Machine” and ID = EQ_ID and Room = Room_IDAnswer

?


Business Name ID Building Dr Smith MDS ATA Building

Room ID Equipment IDA2003 IDQ

Room_ID Bus_IDA2003 MDS

Building Table


Room_Business Table


Comparing two approaches

RDB Semantic Model (Ontology)

Ability to Answer

Questions

Database must be designedto answer the questionsSpecific, typically complex,

queries must be developed

Ontology must be designed to answer the questionsQueries can be generic and

very simple

Ability to Accommoda

te Change

Inflexible:Database structure must be modified so it can continue to answer the questionsQueries must be re-writtenData must be ported

Flexible:Ontology can be easily extended

so it can continue to answer new questions

No data porting required

Processing Speed

Can be very fast with proper tuning – mature technology:

Known optimization approaches

Certain queries, such as multi table joins and self joins are known to cause problems

Not as fast, but improving, tuning does not affect flexibility:

Adding more processing power and distributed computation helps

Performs better than RDBMS for certain query types


Key differences in the representation of relationships

RDB Semantic Model (Ontology)

Cardinality of relationships

Relationships are either 1:1, many:1 or many:manyMany:many relationships must be

broken into many:1 relationships by creating join tables

By default all relationships are many:manyFunctional properties and

cardinality restrictions are used to specify 1:1, many:1 as well as other cardinalities

It is possible to specify, for example, 1:4 or min 2, etc.

Information bearing

relationships

Additional information about the relationship is represented by the extra columns in the join table

Relationship is reified (made into a class)Additional information is

represented as properties of the class

The nature of relationships

ImplicitEmbedded in the name of the

join table or in the name of the columnTypically these names are not

designed for ease of understanding of the nature of the relationship

ExplicitCare is taken to name a relationship

in a way that its nature and intentions are well understood


Another Key Capability of Semantic Web Technology is Managing Distributed Data

Information does not have to be in a single data source

Information about equipment can be in one place

Information about buildings, addresses and doctor offices in a different place

RDF provides and infrastructure for merging and unifying data in a consistent way


Relational and Semantic Technology can work well together: it is not necessarily one or the other!

Semantic ApplicationInteraction LogicApplication Logic

Semantic Interface

ERP

WS

SI

QueryOntology Models

Enterprise Ontology Models

Mapping Mapping Mapping

Schema Translation Models

WS

Semantic Hub

SI

IL

AL

BL

SI

IL

AL

BL PLM

SI

DataWarehouse

CRM

WS

WS

WS

Mapping

LegacySystems

TopQuadrant in collaboration with Jim Hendler presents: “Getting Ready for the Semantic Web with TopBraid Suite”


Module IIa-4:Using Semantic Standards, Languages and TopBraid Tools for Modeling and Querying

Querying RDF with SPARQL


Query Languages

Familiar query languages:SQLXQuery

SPARQL is similar to these in that it allows one to specify patterns of data

SPARQL differs in syntax, e.g., no notion of “JOIN”


Extracting information from RDFRDF is a graph structureHow do I get information from it?

Where is Stratford?Who married the person who wrote King Lear??Did the person who wrote Hamlet live in a Hamlet?


Querying some sample data

ID Title Written By Year1 The Tempest Shakespeare 16112 Romeo and Juliet Shakespeare 15953 As You Like It Shakespeare 15994 Edward II Marlowe 15925 Dido, Queen of Carthage Marlowe 15866 Eastward Ho Johnson 16057 A Game at Chess Middleton 16248 Sir Thomas More Munday 1592

9 The Tragical History of Doctor Faustus Marlowe 1604

Table: Play


Same data viewed as a graph

Row1

Row 2

Row 3

Shakespeare

Johnson

Marlowe

Munday

Middleton

1611

15951599

15921586

1605

1624

1604

writtenBy

year

title

…

rdf:type

Play

The Tempest

Romeo and Juliet

As You Like It

Edward II Row 4

Dido Row 5

Eastward Ho Row 6

Game at Chess Row 7

Sir Thomas More Row 8

Dr. Faustus Row 9


Titles of plays written by Shakespeare

Row 1

Row 2

Row 9

Row 8

Row 7

Row 6

Row 5

Row 4

Shakespeare

Johnson

Marlowe

Munday

Middleton

1611

15951599

15921586

1605

1624

1604

writtenBy

year

title

The Tempest

Romeo and Juliet

As You Like It Row 3

Edward II

Dido

Eastward Ho

Game at Chess

Sir Thomas More

Dr. Faustus


Matching data with graph patterns

The Tempest Row1 Shakespeare

?x ?yThe Tempest Row 1Romeo and Juliet Row 2

?x ?yThe Tempest Row 1Romeo and Juliet Row 2As You Like It Row 3

?x ?yThe Tempest Row 1

Row 2Romeo and Juliet

As You Like It Row 3

?x ?y Shakesepeare

writtenBy

yearHow do we know that these things are plays?

What is a better heading for column “?x”?

title


A more complex graph pattern

?x ?z ?a

The Tempest Shakespeare 1611

?x ?z ?a

The Tempesttt Shakespeare 1611

As You Like It Shakespeare 1599ike Itike It

?x ?z ?a

The Tempes Shakespeare 1611

As You L Shakespeare 1599

Dido Marlowe 1586ido Marl

Row 1

Row 2

Row 9

Row 8

Row 7

Row 6

Row 5

Row 4

Shakespeare

Johnson

Marlowe

Munday

Middleton

1611

15951599

15921586

1605

1624

1604

writtenByyear

title

The Tempest

Romeo and Juliet

Row 3As You Like It

Edward II

Dido

Eastward Ho

Game at Chess

Sir Thomas More

Dr. Faustus

?x ?z ?a

The Tempes Shakespeare 1611

As You L?y ?z

?a

?x Shakespeare 1599

D owe 1586

Thomas More Munday 1592

etc.


Representing graph patterns

Graph patterns are represented just like graphs – in triples!

Variables allowed as well as resources:?x ?y :Shakespeare

?y :title ?x.?y :writtenBy :Shakespeare .

?title ?play :Shakespeare

writtenBy?play :title ?title.?play :writtenBy :Shakespeare . year

title


More graph patterns

?z

?a

?x ?y

writtenBy

?y :title ?x.?y :writtenBy ?z.?y :year ?a.

year

title

?playwright

?year

?title ?y

writtenBy

?y :title ?title.?y :writtenBy ?playwright.?y :year ?year.

year

title


More graph patterns

“The names of two playwrights who wrote plays in the same year”

?play1?playwright1

Play

?year

?play1 rdf:type :Play .?play2 rdf:type :Play .?play1 :writtenBy ?playwright1 .?play2 :writtenBy ?playwright2 .?play1 :year ?year . ?play2 :year ?year .

?play2 ?playwright2

writtenBy

year

title

rdf:type

This finds all plays, so need some way to state that ?playwright1 is different than ?playwright2 (FILTER)


Building Queries from Data

“The names of two playwrights who wrote plays in the same year”

Play

Edward IIMarlowe

1592

?play1 rdf:type :Play .?play2 rdf:type :Play .?play1 :writtenBy ?playwright1 .?play2 :writtenBy ?playwright2 .?play1 :year ?year . ?play2 :year ?year .

Sir Thomas More Munday

writtenBy

year

title

rdf:typeThis is the basis of the automatic query builder in TopBraid Composer and Ensemble


A more complex graph pattern

Row 1

Row 2

Row 9

Row 8

Row 7

Row 6

Row 5

Row 4

Row 3

Shakespeare

Johnson

Marlowe

Munday

Middleton

1611

15951599

15921586

1605

1624

1604

writtenByyeartitle

Play…

Play

rdf:type

The Tempest

Romeo and Juliet

As You Like It

Edward II

Dido

Eastward Ho

Game at Chess

Sir Thomas More

Dr. Faustus

?play1?playwright1

?year

?play2 ?playwright2

?playwright1 ?playwright2Marlowe Munday


Components of a QuerySelection mode and variables

SELECT ?placeSELECT ?playwright1 ?playwright2CONSTRUCT {?playwright rdf:type :Person}

Triple patterns – like a triple, but with named variables instead of some parts

?play :title ?title .?play :playwright :Shakespeare .?play :year ?year .

SPARQL standard is written similar to N3

Filtersnumerical comparisons, calculations?year > 1600

?play1 rdf:type :Play .?play2 rdf:type :Play .?play1 :writtenBy ?playwright1 .?play2 :writtenBy ?playwright2 .?play1 :year ?year . ?play2 :year ?year .FILTER (?playwright1 !=

? l i h 2)


Query SyntaxBring it all together to form a real query:

SELECT ?place WHERE { :Stratford :isIn ?place .}

SELECT ?spouse WHERE

{ ?spouse :married ?author .?author :wrote :KingLear .}

SELECT ?place WHERE{ ?author :wrote :Hamlet .?author :livedIn ?place .?place rdf:type geo:Hamlet . }

Where is Stratford?

Who married the person who wrote King Lear?

Did the person who wrote Hamlet live in a Hamlet?

Separates graph triplesBest practice: end every triple with a '.'


Filters“Shakespearean plays written after 1600”

You can only filter on values you have matched in the WHERE clause!

First, find Shakespearean plays and the years they were written:

writtenByyeartitle

?title ?play Shakespeare

?year

SELECT ?title ?yearWHERE { ?play :title ?title .

?play :writtenBy :Shakespeare .?play :year ?year .

?title ?yearThe Tempest 1611Romeo and Juliet 1595As You Like It 1599

?title ?yearThe Tempest 1611

FILTER (?year > 1600)}


Optional Patterns

“Titles and authors of all plays”Suppose we have some plays whose author is unknown:

ID title writtenBy year101 Maid’s metamporphosis 1600102 Revenger’s Tragedy 16074 Edward II Marlowe 1592

Must match… Optional match

?play ?author?titlewrittenBy

yeartitle

SELECT ?title ?authorWHERE {?play :title ?title .

OPTIONAL {?play :writtenBy ?author .}}

?title ?author

Maid’s metamporphosis

Revenger’s Tragedy

Edward II Marlowe


Negation

“Titles of anonymous plays”

ID title writtenBy year101 Maid’s metamporphosis 1600102 Revenger’s Tragedy 1607

?play ?author?titlewrittenBy

yeartitle

SELECT ?title WHERE {?play :title ?title .

OPTIONAL {?play :writtenBy ?author .}FILTER (!bound (?author))

}

Filter out those for which the author was found using the filter function “bound”:

?titleMaid’s metamporphosisRevenger’s Tragedy

The variable ?author was not bound to a value


Searching for Literals

Previous queries matched a variable (e.g. ?title)find something with a specific literal (xsd) value

Who wrote “A Game at Chess”?SELECT ?author

WHERE { ?play :title "A Game at Chess" .?play :writtenBy ?author .

}

Order matters: each graph pattern further restricts the overall match

SELECT ?authorWHERE { ?play :title "A Game at Chess"^^xsd:string .

?play :writtenBy ?author .} specify xsd type

SELECT ?authorWHERE {?play :title ?title .

FILTER (regex(?title, "a game", "i")) .}

Regular expression defined by XQUERY 1.0regex(?title, "[a-zA-Z]{2}[aeiou]s{2}$”)matches when end of string is “Chess” (as well as other string combinations)


Union

Find all plays written by Shakespeare either in 1611 or 1595

SELECT ?play ?title ?yearWHERE {

{ ?play :writtenBy :Shakespeare .?play :title ?title .?play :year "1611"^^xsd:string .

}UNION{ ?play :writtenBy :Shakespeare ;

:year ?year .FILTER(regex(?year, "1595")) .

}}

?play ?title ?year:Play1 The Tempest

:Play2 1595

The query matches two different graph patterns:1.Matches ?play and ?title with specified :year2.Matches ?play and ?year filtered by ?year?play has different binding in each of the graph patterns


Query Forms

SELECTreturns matches for specified variables

CONSTRUCTreturns a graph that includes triples constructed from specifiedvariables

ASKtrue if a match to the graph pattern is found

DESCRIBEreturns a graph (instead of selecting “columns”) – not supported by TBC


ASK

ASK returns a Boolean valuebased on whether WHERE clause finds data

Most useful in programsSPINSPARQLMotion, JSP, etc.

Result displayed in status bar

Were any plays written after 1600?


CONSTRUCT

SPARQL queries can build new sets of triples based on patternsWHERE clause exactly as beforeCONSTRUCT returns a triple pattern

Subtly powerful:Under these conditions, add these triplesBasically what reasoners do (datalog)

plays are written by playwrights

CONSTRUCT {?person rdf:type :playwright}WHERE { ?play :writtenBy ?person .

?play rdf:type :Play .}


Constructing new triples with SPARQL

Play 1 Shakespeare

Play 2

Play 9

Play 8

Play 7

Play 6

Play 5

Play 4

Play 3Johnson

Marlowe

Munday

Middleton

Playwright

Play

writtenBy

rdf:type

SELECT CONSTRUCT

?person ?personSame binding re-used from body to head

Play ?play

Playwright

TopQuadrant in collaboration with Jim Hendler presents: “Getting Ready for the Semantic Web with TopBraid Suite”


Module IIa-3:Using Semantic Standards, Languages and TopBraid Tools for Modeling and Querying

SKOS – Simple Knowledge Organization System


What is a Knowledge Organization System?

A means of organizing and communicating terminology about a domain

Controlled VocabularyTaxonomy Thesaurus

Thesaurus standardsNISO Z39.19, ISO 2788-1986(E), ISO 5964-1985(E)Provide for relationships between terms• BT, NT, RT• Preferred terms, alternate terms

Monolingual, Multilingual, hierarchical


Vocabulary Uses

Tagging, e.g.:del.icio.us, FlickrWest Key Number SystemLibrary of Congress etc.

Entity Extraction, e.g.:Calais

Allow one set of expert users (‘catalogers’) to inform another set (information customers) to communicate about the content of information items(documents, photos, web pages, etc.)

Data ModelingData dictionaries, schemasSpreadsheet columns

Supports consistency in data modeling, promoting interoperability.


Agreeing on terms

Why can’t everyone just agree to use terms the same way?

… Everyone has their own business processes and stakes.

Disagreement is legitimate!


Simple Knowledge Organization System

SKOS is the RDF standard for Knowledge Organization SystemsAllows different groups to organize terminology…… while allowing them to link to one another

“The St. Louis notion of ‘Customer’ is broader than the New York notion of ‘Customer’”

You can’t even have this discussion, if you don’t recognize that there are actually two contexts for the word

“Customer”!


Mapping terms

broader match

“Customer”“Customer”


SKOS Resources

Qname label Abbreviation(where applicable)

skos:broader “has broader term” BT

skos:narrower “has narrower term” NT

skos:related “has related term” RT

skos:broadMatch “has broader match”

skos:narrowMatch “has narrower match”

skos:prefLabel “preferred label”

skos:altLabel “alternative label”

dean allemang semantic web basics

Technology

current web

ofthe web

web definedand

interlingua copyright

mapping web pages

topic copyright

web content machinereadable

web page interaction