The Semantic Web

Schedule for this evening• Review of the survey

– Summary. Discussion if wanted• Some other ways to move content from

place to place– FTP– OAI – PMH

• Then, the Semantic Web– An introduction to things to come

Survey• Summary on Word document• Responses and any comments

Other ways to move materials in the Internet

• FTP – File Transfer Protocol– One of the oldest of the Internet protocols– Originally, command line interface– Now, many GUI versions

• Host must run a server version that listens on port 20 (default)

• Client requests a session, user logs in, issues a sequence of commands including get and put.

Brief demonstration

Open Archives Intiative• Generally oriented toward sharing

information about resources in collections accessible on the Internet

• There is a protocol for sharing – Based on XML so we will look at that first

Semantic Web• Semantics refers to meaning.• The semantic web aims to have enough

information about a resource available that a program can use resources as if the program could understand what the resources are.– Of course, the program does not really

“understand” in the human sense.– However, if it has enough information, it can

follow rules and behave in ways that are consistent with understanding what it is working with.

Markup• HTML is a markup language

– not the first, by any means• Tags in HTML give clues to the reader

(browser or other program) about what to do in displaying or presenting the marked text.– emphasize, make stand out (like a title or section

head), break – Some allowance for meta tags

• HTML has been stretched beyond its original design

XML• Simplified version of SGML

– Language for defining languages (markup languages)

– HTML is now XHTML and is an XML language

– XML allows you to make up your own descriptive language

Metadata• Critical part of the description of content

and resources• What does metadata look like?• Metadata is data about data

– Information about a resource, encoded in the resource or associated with the resource.

• The language of metadata: XML– eXtensible Markup Language

XML• XML is a markup language• XML describes features• There is no standard XML• Use XML to create a resource type• Separately develop software to interact

with the data described by the XML codes.

Source: tutorial at w3school.com

XML rules• Easy rules, but very strict• First line is the version and character set

used: – <?xml version="1.0" encoding="ISO-8859-1"?>

• The rest is user defined tags• Every tag has an opening and a closing

Element naming

• XML elements must follow these naming rules:– Names can contain letters, numbers, and other

characters– Names must not start with a number or

punctuation character– Names must not start with the letters xml (or XML

or Xml ..)– Names cannot contain spaces

Elements and attributes

• Use elements to describe data• Use attributes to present information

that is not part of the data– For example, the file type or some other

information that would be useful in processing the data, but is not part of the data.

Repeating elements

• Naming an element means it appears exactly once.

• Name+ means it appears one or more times

• Name* means it appears 0 or more times.

• Name? Means it appears 0 or one time.

Parts of an XML document• Elements

– The components of an XML document– Some contain other parts, some are empty

• Ex in HTML: “br” or “table” in XML “ingredient”

• Attributes– Information about elements, not data

• Ex in HTML “src=” in XML “scale=”

• Entities– Special characters or strings with pre-assigned meaning

• Ex in HTML &nbsp for non-breaking space

• PCDATA– Parsed Character data: text that will be parsed and interpreted by the

reader. Tags and entities will be expanded and used in presentation.• CDATA

– Character data: text that will not be parsed and interpreted. It will be displayed exactly as provided.

The HTML examples are familiar; the XML examples are made up – dependent on the specific XML scheme used

Using XML - an example

Define the fields of a recipe collection:<?xml version="1.0" encoding="ISO-8859-1"?><recipe><recipe-title> </recipe-title><ingredient-list> <ingredient> <ingredient-amount> </ingredient-amount> <ingredient-name> </ingredient-name> </ingredient></ingredient-list><directions></directions></recipe> ISO 8859 is a character set.

See http://www.bbsinc.com/iso8859.html

Processing the XML data• How do we know what to do with the

information in an XML file?– Document Type Definition (DTD)

• Put in the same file as the data -- immediate reference

• Put a reference to an external description• Provides the definition of the legitimate content

for each element

Document Type Definition

• <?xml version="1.0" encoding="ISO-8859-1"?>• <!DOCTYPE recipe [• <!ELEMENT recipe (recipe-title, ingredient-list, directions)>• <!ELEMENT recipe-title (#PCDATA)>• <!ELEMENT ingredient-list (ingredient)>• <!ELEMENT ingredient (ingredient-amount, ingredient-name)*>• <!ELEMENT ingredient-amount (#PCDATA)>• <!ELEMENT ingredient-name (#PCDATA)>• <!ELEMENT directions (#PCDATA)> ]>

Repeat 0 or more times

<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE recipe SYSTEM “recipe.dtd”><recipe><recipe-title> Meringue cookies</recipe-title><ingredient-list> <ingredient> <ingredient-amount>3 </ingredient-amount> <ingredient-name> egg whites</ingredient-name> </ingredient> <ingredient> <ingredient-amount> 1 cup</ingredient-amount> <ingredient-name> sugar</ingredient-name> </ingredient> <ingredient> <ingredient-amount>1 teaspoon </ingredient-amount> <ingredient-name> vanilla</ingredient-name> </ingredient> <ingredient> <ingredient-amount>2 cups </ingredient-amount> <ingredient-name>mini chocolate chips </ingredient-name> </ingredient></ingredient-list><directions>Beat the egg whites until stiff. Stir in sugar, then vanilla. Gently fold in

chocolate chips. Place in warm oven at 200 degrees for an hour. Alternatively, place in an oven at 350 degrees. Turn oven off and leave overnight.

</directions> </recipe>

Not the way that I want to see a recipe in a magazine!

What could we do with a large collection of such entries?

How would we get the information entered into a collection?

External reference to DTD

Spot Check• Design an XML schema for an application

of your choice. Keep it simple.• Examples -- address book, TV program

listing, DVD collection, …

• Work in pairs and discuss your choice and your solution

Anot

her e

xam

ple

• A paper with content encoded with XML: http://tecfaseed.unige.ch/staf18/modules/ePBL/uploads/proj3/paper81.xml

• First few lines:• <?xml version="1.0" encoding="ISO-8859-1"?>• <?xml-stylesheet href="ePBLpaper11.css" type="text/css"?>• <?xml-stylesheet href="ePBLpaper11.xsl" type="text/xsl"?>• <!DOCTYPE paper SYSTEM "ePBLpaper11.dtd">• <paper id="proj3">• <info>• <title>Standards E-learning and their possible support for a rich

pedagogic approach in a 'Integrated Learning' context</title>• <authors>• <author>• <firstname>Rodolophe</firstname>• <familyname>Borer</familyname>• <homepageurl>http://tecfa.unige.ch/perso/staf/borer/</

homepageurl>• <email/>• </author>• </authors> "ePBLpaper11.dtd” shown on next slide

<?xml version="1.0" encoding="ISO-8859-1" ?><!-- _________ _____________________ --><!-- ePBL-project DTD for student project management

& specification --><!-- Copyright: (2004)

Paraskevi.Synteta@tecfa.unige.ch --><!-- http://tecfa.unige.ch/~paraskev/ --><!-- Daniel K. Schneider --><!-- http://tecfa.unige.ch/tecfa-people/schneider.html--><!-- Created: 13/11/2002 (based on EVA_pm grammar) --><!-- Updated: 07/05/2004 --><!-- VERSIONS --><!-- v1.1 Adaptations to use with Morphon xml editor

and addition of IDs--><!-- ____________________ --><!-- _ ENTITY DECLARATIONS ______ --><!ENTITY % foreign-dtd SYSTEM "ibtwsh6_ePBL.dtd">%foreign-dtd;<!ENTITY % id "id ID #IMPLIED"><!-- ______ MAIN ELEMENT _________ --><!ELEMENT project (name, authors, date, updated,

goal, state-of-the-art, research-development-questions, methodology, workpackages ) >

<!ELEMENT name (#PCDATA )><!ELEMENT date (#PCDATA )><!ELEMENT authors (#PCDATA )>

<!ELEMENT updated (#PCDATA )><!ELEMENT goal (title, description )><!ELEMENT state-of-the-art %vert.model;><!ATTLIST state-of-the-art %id;><!ELEMENT research-development-questions (question )

+>

<!ELEMENT question (title, description )><!ELEMENT methodology %vert.model;><!ATTLIST methodology %id;><!ELEMENT workpackages (workpackage )+><!ELEMENT workpackage (planning, objectives,

deliverables )><!ATTLIST workpackage %id;><!ELEMENT objectives (objective )+><!ELEMENT objective (title, description )><!ELEMENT deliverables (deliverable )+><!ELEMENT deliverable (url, title, description )><!ELEMENT url (#PCDATA )><!ELEMENT planning (from, to, progress )><!ELEMENT from (#PCDATA )><!ELEMENT to (#PCDATA )><!ELEMENT progress (#PCDATA )><!-- ________________________ --><!ELEMENT title (#PCDATA )><!ATTLIST title %id;><!ELEMENT description %vert.model;><!-- _______________________ -->

Source: http://tecfa.unige.ch/staf/staf-j/vuilleum/staf18/p6/No longer there

Resource sharing• On your projects, you had to go looking for

the materials that you need• You look at the site, see what is there,

consider how it could be used in your project.

• On a large scale, that does not work so well.

• It would be nice to query a site and ask what is there that might be of interest to us.

Distributed ResourcesMultiple Services

Service provider -- search, browse, compare, etc.

Data provider

Data provider

Data provider

Data provider

Data provider

One service provider gathers information about data and uses it to provide services

Open Archives Initiative (OAI)

• Web-based– Uses HTTP to communicate between sites

• Centralized server– Services provided from a site that has

already gathered the information it needs for those services from a distributed collection of sites.

OAI PMH

• Interoperability through Metadata Exchange

• The Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) is a low-barrier mechanism for repository interoperability. Data Providers are repositories that expose structured metadata via OAI-PMH. Service Providers then make OAI-PMH service requests to harvest that metadata. OAI-PMH is a set of six verbs or services that are invoked within HTTP.

http://www.openarchives.org/pmh/

OAI PMH verbs• Identify• ListMetadataformats• ListSets• Listidentifiers• Listrecords• Getrecord

Open Archives Initiative Protocol for Metadata Harvesting -- OAI-PMH

Repository

OAI

Harvester

OAI

HTTP req (OAI verb)

HTTP resp (XML)

OAI PMH defines an interface between the Harvester and any number of Repositories

Metadata Provider

Service Provider

Implemented as CGI, ASP, PHP, or other

Any system may serve as a harvester, repository, or both

OAI - PMH componentsService Providers and Data Providers

Requests and Responses

http://www.oaforum.org/tutorial/english/page3.htm#section3

Records• Metadata of a resource.• Three parts

– Header (required)• Identifier (required: 1 only)• Datestamp (required: 1 only)• setSpec elements (optional: 0, 1, or more)• Status attribute for deleted item

– Metadata (required)• XML encoded metadata with root tag, namespace• Repositories must support Dublin Core, other formats

optional– “About” statement (optional)

• Right statements• Provenance statements

Dublin Core elementssee: http://dublincore.org/documents/dces/

• Title• Creator • Subject - C• Description• Publisher• Contributor• Date • Type - C

• Format - C• Identifier• Source• Language• Relation• Coverage - C

• RightsRights Management information

Space, time, jurisdiction.

C = controlled vocabulary recommended.

Ref. to related resource

Standards RFC 3066, ISO639

Unambiguous ID

Ex: collection, dataset, event, image

YYYY-MM-DD, ex.

Entity primarily responsible for making content of the resource

Entity making the resource available

Contributor to content of the resource

What is needed to display or operate the resource.

Identifiers• Globally unique identifier• Valid URI

– Examples• oai:<archiveId>:<recordId>• oai:etd.vt.edu:etd-1234567890

– Must resolve to one item• No duplicates• No reuse of previously used identifiers

Datestamps• Date of last modification of a record

– Used only for harvesting (meta metadata?)• Mandatory for each item in the repository• Two levels of granularity possible

– YYYY-MM-DD– YYYY-MM-DDThh:mm:ssZ

• T … Z = Time zone -- must be GMT

• Allows harvesting incrementally -- get only what is new since last visit– Accessed by arguments from and until

The OAI-PMH verbs• Each requests a specific response from a

data repository

Identify• Function: Description of the archive• Example: http://www.language-archives.org/cgi-bin/olaca3.pl?verb=Identify• Parameters: none• Errors/exceptions:

– badArgument (there should not be any)• Response format:Element Example

Ordinality ‡repositoryName My Archive

1baseURL http://archive.org/oai

1protocolVersion 2.0

1earliestDatestamp 1999-01-01

1deleteRecords no, transient, persistent

1granularity YYYY-MM-DD, YYYY-MM-DDThh:mm:ssZ

1adminEmail oai-admin@archive.org

+compression deflate, compress

*description oai-identifier, eprints, friends, …

* ‡ Ordinality: 1 = mandatory, 1 only; + = mandatory, 1 only; * = optional, 0 or more

Actual response from

http://www.language-archives.org/cgi-bin/olaca3.pl?verb=Identify

Continued

<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2011-11-13T02:01:52Z</responseDate><request verb="Identify">http://www.language-archives.org/cgi-bin/olaca3.pl</request><Identify><repositoryName>OLAC Aggregator</repositoryName><baseURL>http://www.language-archives.org/cgi-bin/olaca3.pl</baseURL><protocolVersion>2.0</protocolVersion><adminEmail>haejoong@ldc.upenn.edu</adminEmail><earliestDatestamp>1900-01-01</earliestDatestamp><deletedRecord>no</deletedRecord><granularity>YYYY-MM-DD</granularity><!-- maybe later <compression>identity</compression> --><description><oai-identifier xmlns="http://www.openarchives.org/OAI/2.0/oai-identifier" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai-identifier http://www.openarchives.org/OAI/2.0/oai-identifier.xsd">

Continued

<scheme>oai</scheme><repositoryIdentifier>OLACA.language-archives.org</repositoryIdentifier><delimiter>:</delimiter><sampleIdentifier>oai:ethnologue.com:aaa</sampleIdentifier></oai-identifier></description><description><olac-archive xmlns="http://www.language-archives.org/OLAC/1.1/olac-archive" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" type="institutional" xsi:schemaLocation="http://www.language-archives.org/OLAC/1.1/olac-archive http://www.language-archives.org/OLAC/1.1/olac-archive.xsd" currentAsOf="2011-10-31"><archiveURL>http://www.language-archives.org/archive_records/</archiveURL><participant name="Steven Bird" role="Curator" email="sb@csse.unimelb.edu.au"/><participant name="Gary Simons" role="Curator" email="Gary_Simons@sil.org"/><participant name="Haejoong Lee" role="Administrator" email="haejoong@ldc.upenn.edu"/><institution>Open Language Archives Community</institution><institutionURL>http://www.language-archives.org/</institutionURL><shortLocation>Philadelphia, U.S.A.</shortLocation><location/>

<synopsis>This repository contains all records from OLAC-registered archives. It is intended to be used by services which do not want to harvest individual OLAC archives.</synopsis><access>Metadata may be used only subject to the access permissions given by the individual archives.</access></olac-archive></description></Identify></OAI-PMH>

ListMetadataFormats

• Function: retrieve available metadata formats from archive

• Example: archive.org/oai-script?verb=ListMetadataFormats&• identifier=oai:HUBerlin.de:3000218

• Parameters: identifier (optional)• Errors/exceptions:

– badArgument– idDoesNotExist– noMetadataFormats

− <OAI-PMH xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2006-10-17T01:58:06Z</responseDate><request verb="ListMetadataFormats">http://www.language-archives.org/cgi-bin/olaca3.pl</request>− <ListMetadataFormats>− <metadataFormat><metadataPrefix>olac</metadataPrefix><schema>http://www.language-archives.org/OLAC/1.0/olac.xsd</schema><metadataNamespace>http://www.language-archives.org/OLAC/1.0/</metadataNamespace></metadataFormat>− <metadataFormat><metadataPrefix>olac_display</metadataPrefix><schema>http://www.language-archives.org/OLAC/1.0/olac.xsd</schema><metadataNamespace>http://www.language-archives.org/OLAC/1.0/</metadataNamespace></metadataFormat>− <metadataFormat><metadataPrefix>oai_dc</metadataPrefix><schema>http://www.openarchives.org/OAI/2.0/oai_dc.xsd</schema><metadataNamespace>http://www.openarchives.org/OAI/2.0/oai_dc/</metadataNamespace></metadataFormat></ListMetadataFormats></OAI-PMH>Re

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ListSets• Function: retrieve set structure of a repository

• Example: archive.org/oai-script?verb=ListSets• Parameters: resumptionToken (exclusive)• Errors/exceptions:

– badArgument– badResumptionToken– noSetHierarchy

Sets are optional and are used to divide a repository into separate units that will be of interest to different harvesters.

ListIdentifiers• Function: abbieviated form of ListRecords, retrieve only

headers• Example: archive.org/oai-script?verb=ListIdentifiers&metadataPrefix=

oai_dc&from=2002-12-01

• Parameters:– from (optional)– until (optional)– metadataPrefix (required)– set (optional)– resumptionToken (exclusive)

• Errors/exceptions:– badArgument– badResumptionToken– cannotDisseminateFormat– noRecordsMatch– noSetHierarchy

ListRecords• Function: harvest records from a repository• Example: archive.org/oai-script?verb=ListRecords&

metadataPrefix=oai_dc&set=biology• Parameters:

– from (optional)– until (optional)– metadataPrefix (required) – set (optional)– resumptionToken (exclusive)

• Errors/exceptions:– badArgument– badResumptionToken– cannotDisseminateFormat– noRecordsMatch– noSetHierarchy

GetRecord• Function: retrieve an individual metadata record

from a repository• Example:archive.org/oai-script?verb=GetRecord&identifier=oai:HUBerlin.de:

3000218 &metadataPrefix=oai_dc

• Parameters:– Identifier (required)– metadataPrefix (required)

• Errors/exceptions:– badArgument– cannotDisseminateFormat– idDoesNotExist

Interoperability• The goal: communication, without human

intervention, between information sources– Books that “talk to each other”

• Live links for references• Knowledge of how to find relevant resources

when needed• Ability to query other information locations

Protocols• Precise rules for interactions between

independent processes– Format of the messages

• Both structure and content

– Specified behavior in response to specific messages

• Many ways to accomplish the same result, but both sides must have the same understanding of the rules of engagement.

Spot Check• Make up a protocol• Suppose we wanted a kind of command and

control protocol so that a master site could cause a satellite site to clear the screen that is displayed to the web.

• We want the response to be prompt• We want the satellite site to confirm receipt of

the command and to notify the master when the site screen has been cleared.

• It should be possible to accomplish this with messages between the two sites and an action at the satellite site.

The Semantic Web• Some of these slides come from Lee

Giles – Who, in turn, credits Jim Hendler, Carl

Lagoze, Jayavel Shanmugasundaram, Sara Cohen, Jonathan Mamou, Yaron Kanza, Mark Sapossnek, Yehoshua Sagiv, Frank van Harmelen

Beyond XML• Building with XML, new languages have

emerged to– Describe content, and things in general– Relationships between things– Attributes (characteristics) of things

• The semantic web requires that things be described in sufficient detail that autonomous processes can discover useful things and use them properly

Motivation for the Semantic Web

• Search engines• concepts, not keywords• semantic narrowing/widening of queries

• Shopbots• semantic interchange, not screenscraping

• E-commerce– Negotiation, catalogue mapping, personalization

• Web Services– Need semantic characterizations to find them

• Navigation• by semantic proximity, not hardwired links

• .....

Example• Try these queries with Google:

– Distance between Paris and Madrid Google returns:

– (The) Largest city of France • Google returns: France – Largest City: Paris

– (The) Largest city of Spain • Google returns: Spain – Largest City: Madrid

• Now, try these with Google:– Distance between largest city of France and largest city of Spain– Distance between “largest city of France” and “largest city of

Spain”– And worst, Distance between “the largest city of France” and

“the largest city of Spain” – No result returned by Google!• Actually now shows a link to several versions of these slides!

Distance between Madrid spain and Paris francewww.mapcrow.info/Distance_between_Madrid_SP_and_Paris_FR.htmlCOORDINATES +. TOTAL DISTANCE. Madrid, SP, -3.6833 40.4000. Paris, FR, 2.3333 48.8667. Miles: 654.57. Kilometers: 1053.40. Bearing: NE. Madrid, SPAIN ...

http://www.w3.org/DesignIssues/diagrams/sw-stack-2005.png

Semantic Web Stack

RDF and OWL• Resource Description Framework (RDF)• Web Ontology Language (OWL)

So why not just use XML?• No agreement on:

– structure• is country a:

– object?– class?– attribute?– relation? – something

else?• what does

nesting mean?– vocabulary

• is country the same as nation?

<country name=”Netherlands”> <capital name=”Amsterdam”> <areacode>020</areacode> </capital></country>

<nation> <name>Netherlands</name> <capital>Amsterdam</capital> <capital_areacode> 020 </capital_areacode></nation>

● Are the above XML documents the same?● Do they convey the same information?● Is that information machine-accessible?

“2nd aim of Semantic Web”: Data integration

– Unstructured and sensors, programs, services semi-structured sources (document collections, message traffic, web pages, ...)

– Structured data without an explicit data schema (non-local databases, data tables, charts and reports, ...)

– Non-Text collections (image, video, sound, ...) – Streams of data

Must specify the structure of data resources..

2nd aim of Semantic Web: Data integration

... so a processor can tell how the "attributes" and "values" are related

– What is required vs. optional? – How many values for a particular attribute? – What attributes are keys for other

attributes? – Which attributes are necessarily related to

other attributes and in what way?? – How do the attributes (and values) in one

data source map to attributes and values describing another source?

Stack of languages• XML:

– Surface syntax, no semantics• XML Schema:

– Describes structure of XML documents• RDF:

– Datamodel for “relations” between “things”• RDF Schema (RDFS):

– RDF Vocabulary Definition Language• OWL:

– A more expressive Vocabulary Definition Language

Semantic web languages today• Today there are three semantic web

languages– RDF – Resource Description Framework

http://www.w3.org/RDF/– DAML+OIL – Darpa Agent Markup Language

http://www.daml.org/ (deprecated)– OWL – Ontology Web Language

http://www.w3.org/2001/sw/• OWL lit• OWL DL• OWL Full

RDF is the first Semantic Web language

<rdf:RDF ……..> <….> <….></rdf:RDF>

XML EncodingGraph

stmt(docInst, rdf_type, Document)stmt(personInst, rdf_type, Person)stmt(inroomInst, rdf_type, InRoom)stmt(personInst, holding, docInst)stmt(inroomInst, person, personInst)

Triples

RDFData Model

Good for MachineProcessing

Good For HumanViewing

Good For Reasoning

RDF is a simple language for building graph based representations

The RDF Data Model• An RDF document is an unordered collection of

statements, each with a subject, predicate and object (aka triples)

• A triple can be thought of as a labelled arc in a graph• Statements describe properties of web resources• A resource is any object that can be pointed to by a URI:

– a document, a picture, a paragraph on the Web, …– E.g., http://umbc.edu/~ypeng/F07671.html – a book in the library, a real person (?)– isbn://5031-4444-3333– …

• Properties themselves are also resources (URIs)

RDF without a Schema• Object ->Attribute-> Value triples

• objects are web-resources• Value is again an Object:

• triples can be linked• data-model = graph

pers05 ISBN...Author-of

pers05 ISBN...Author-of

MIT

ISBN...

Publ-by

Author-of Publ-

by

What does RDF Schema add?• Defines vocabulary for RDF• Organizes this vocabulary in a

typed hierarchy• Class, subClassOf, type• Property, subPropertyOf• domain, range

Person

Author Reader

subClassOfsubClassOf

Lynda

type

communicatesTodomain range

Frank

type

communicatesTo

Which Semantic Web?

• Version 1:"Semantic Web as Web of Data" (TBL)

• recipe:expose databases on the web, use XML, RDF, integrate

• metadata from:– expressing DB schema semantics

in machine interpretable ways• enable integration and unexpected re-use

Which Semantic Web?

• Version 2:“Enrichment of the current Web”

• recipe:Annotate, classify, index

• metadata from:– automatically producing markup:

named-entity recognition, concept extraction, tagging, etc.

• enable personalization, search, browse,..

Which Semantic Web?

• Version 1:“Semantic Web as Web of Data”

• Version 2:“Enrichment of the current Web”

Different use-cases Different techniques Different users

The Evolving WebWeb ofKnowledge

HyperText Markup LanguageHyperText Transfer Protocol

Resource Description FrameworkeXtensible Markup Language Self-Describing Documents

Foundation of the Current Web

Proof, Logic andOntology Languages Shared terms/terminology

Machine-Machine communication

1990

2000

2010

Berners-Lee, Hendler; Nature, 2001

DOCUMENTS

DATA/PROGRAMS