W3C Standards

(1)

Seminar

Ubiquitous Information

WS 00/01 ETH Zurich

W3C Standards

Vlad Coroama Marc Langheinrich

(2)

What´s coming up?

All about the W3C

– History, Members, Process, Domains

XML Technology Primer

– XML, XML Schemas, XML Linking, XML Style

The Semantic Web

– Metadata: RDF & Applications (CC/PP), XML Protocols & SOAP, The Web of Trust

Summing Up

W3C Standards

(3)

W3C History

Founded 10/1994 by Tim Berners-Lee at MIT/LNCS

– 4/95 INRIA hosts W3C Europe

– 4/96 Keio University hosts W3C Asia

Led by Jean-Francois Abramatic (Chairman) and Tim Berners-Lee (Director)

Goals:

– Universal Access – Semantic Web – Web of Trust

More than

– 20 specs in 5 years

– 50 staff members across hosts institutions

Tim Berners-Lee

Jean-Francois Abramatic

W3C Logo

I. All about the W3C

(4)

W3C Members

497 members as of 01/2001

– Companies: AOL, Appel, AT&T, Cisco, Citibank ...

– Universities: MIT, Vrije Universiteit ...

– Governmental Agencies: US EPA, Datenschutz- Zentrum Schleswig Holstein ...

Yearly Membership Fee

– US$ 50,000.- corporate members

– US$ 5,000.- if annual revenues < US$ 50‘000‘000 – US$ 5,000.- non-profit, governmental

(5)

W3C Process

Advisory Committee

– One representative from each member

• send submission requests from their organization

• nominate colleagues for W3C working groups

– Reviews proposals for activities, recommendations

Advisory Committee (AC) AC representatives Organisations^Member Director

convene proposes

activities W3C Working Groups

submit specifications for recommendation

approve acctivities

W3C Team organizes

(6)

W3C Activities

Submissions

– Allows members to propose technology/ideas to W3C for consideration

– Must include IPR statement – Reviewed by W3C Team

• If accepted, published as W3C Note

Member Organisations AC representatives

W3C Team acknowledges

Submissions W3C Note

Influence proposal of activities

Director

(7)

W3C Recommendations

Candidate Recommendation (CR)

Public Working Draft Last Call Draft

Proposed Recommendation (PR) Working Draft (WD)

Recommendation (Rec)

• members only

• updated often

1 2 3

4 5

6

(8)

W3C Recommendations

• members only

• updated often • interim draft

• for public comment

• required: one every 3 month

1 2 3

4 5

6

(9)

W3C Recommendations

• members only

• WG: „We‘re done“

• for public & W3C comment

• lasts 3-4 weeks Back to WD?

1 2 3

4 5

6

Last Call

(10)

W3C Recommendations

• members only

• lasts 3-4 weeks

Director

dependencies ok?

approves

• WG requests implementations

• 0-12 months (may be skipped) Back to WD?

Back to WD?

1 2 3

4 5

6

^CR

Last Call

(11)

W3C Recommendations

• members only

• lasts 3-4 weeks

Director

dependencies ok?

approves

• for review by AC

• at least 4 weeks

• public promotion by AC reps

• 0-12 months (may be skipped) approves

Back to WD?

1 2 3

4 5

6

^PR ^CR

Last Call

(12)

W3C Recommendations

• members only

• lasts 3-4 weeks

Advisory Committee (AC) approves

Director

dependencies ok?

approves

• for review by AC

• at least 4 weeks

• public promotion by AC reps

• 0-12 months (may be skipped) approves

• W3C considers refined &

ready for widespread deployment

• only minor errata

Back to WD?

1 2 3

4 5

6

^PR ^CR

Last Call

W3C Rec

(13)

W3C Domains

Architecture

– HTTP, DOM, URI, XML, XML Protocols

Technology & Society Domain

– XML Encryption, XML Signature, Privacy (P3P), Metadata, Electronic Commerce

User Interface

– HTML, Graphics, I18N, Math, Mobile, Multimedia, Style, TV/Web, VoiceBrowser

Web Accessibility Initiative (WAI)

(14)

W3C Activities

W3C

Architecture

Technology

&

Society

User Interface

Accessibility

XML

Graphics

XML Encryption XML

Signature Privacy

XML Protocol HTTP

URI DOM

Multimedia

I18N

TV/Web

Program Office

Technical Activity

Jigsaw

Amaya Mobile Access

Math

Style

Voice

Browser HTML

Linking XPointer SOAP

DOM

DOM 2

HTTP 1.1 HTTP Ext

2.1.1 Planning

Query

Schema XLink

Core Canonical

xmldsig P3P 1.0

APPEL

Metadata

PICS RDF

E-commerce

Micropay

SVG

PNG Char-

Model Ruby

Layout Unicode

CC/PP

MathML 1.01

2.0 DOM 1

SYMM

SMIL 1.0

2.0

XPath XSL

CSS CSS1 CSS2 CSS3

XSLT

tv: VoiceXML

Grammar

Speech Synth Natural Language Multimodal

WCAG ATAG

UAAG

XForms

HTML 3.2

XHTML

tidy

Module Basic Events

1.1 2.0

4.0 4.2.1

RDF Schema

(15)

What´s coming up?

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

W3C Standards

(16)

The X-Files

XML Core

– DTD, Namespaces

XML Linking

– XLink, XBase, XPointer, XPath

XML Style

– XSL, XSLT

XML Schema

More XML

– XML Protocol – XML Signature – XML Query

– XML Encryption – XHTML

II. XML Technology Primer

(17)

Other stuff

Semantic Web

– RDF – P3P – CC/PP – SOAP

SyncML

SVG / SMIL

VoiceBrowser

(18)

XML Activity

XML Query Working Group

XML Schema Working Group

– XML Schema: Primer, Structures, Datatypes

XML Linking Working Group

– XPointer, XLink, XML Base

XML Core Working Group

– Advances XML specification. XML Fragment, XInclude, XML Information Set

Old: XML Namespaces, XML Style Sheets (XSL)

Others: XML Protocols, XML Encryption, XML Signature

(19)

W3C Activities

W3C

Architecture

Technology

&

Society

User Interface

Accessibility

XML

Graphics

XML Encryption XML

Signature Privacy

XML Protocol HTTP

URI DOM

Multimedia

I18N

TV/Web

Program Office

Technical Activity

Jigsaw

Amaya Mobile Access

Math

Style

Voice

Browser HTML

Linking XPointer SOAP

DOM

DOM 2

HTTP 1.1 HTTP Ext

2.1.1 Planning

Query

Schema XLink

Core Canonical

xmldsig P3P 1.0

APPEL

Metadata

PICS RDF

E-commerce

Micropay

SVG

PNG Char-

Model Ruby

Layout Unicode

CC/PP

MathML 1.01

2.0 DOM 1

SYMM

SMIL 1.0

2.0

XPath XSL

CSS CSS1 CSS2 CSS3

XSLT

tv: VoiceXML

Grammar

Speech Synth Natural Language Multimodal

WCAG ATAG

UAAG

XForms

HTML 3.2

XHTML

tidy

Module Basic Events

1.1 2.0

4.0 4.2.1

RDF Schema

(20)

XML Tech Tree

XML

Web heute Web morgen

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

XML Signature Canonical XML

(21)

XML

XML Tech Tree

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

(22)

XML

markup language for documents containing structured information

XML is not HTML

– specifies neither semantics nor tag set

- meta-language for describing markup languages

restricted form of SGML

– thereby usable on the Web

(23)

XML structure

Content

Markup

– elements

• attributes

– entity references – comments

– processing instructions – marked sections

– document type definitions (DTDs)

(24)

XML (cont.)

XML Documents can be

– Well-formed

• comply simplest syntactic rules

– Valid

• obeys the constraints of a DTD (Document Type Definition)

DTD

– context-free grammar

– defines tag set for a specific markup vocabulary

(25)

XML Example

<?xml version="1.0"?>

<burns>Say <quote>goodnight</quote>, Gracie.</burns> <allen><quote>Goodnight, Gracie.</quote></allen>

</oldjoke>

<!ELEMENT oldjoke (burns+, allen, applause?)>

<!ELEMENT burns (#PCDATA | quote)*>

<!ELEMENT allen (#PCDATA | quote)*>

<!ELEMENT quote (#PCDATA)*>

<!ELEMENT applause EMPTY>

(26)

XML Namespaces

Name collisions for XML markup

– single XML document contains elements and attributes defined in different vocabularies

⇒ every tag needs to be unique

XML Namespace = collection of names, uniquelly identified by a URI reference

– used in XML documents as element types and attribute names

<?xml version="1.0"?>

</x>

(27)

XML Tech Tree

XML

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

(28)

XSL

language for expressing stylesheets, consisting of

1. language for transforming XML documents (XSLT), and

2. an XML vocabulary for specifying formatting semantics

(29)

XSLT

language for transforming XML documents into other XML documents

Part of XSL (which is XSLT + XML vocabulary for formatting)

A transformation expressed in XSLT describes rules for transforming a source tree into a result tree

The transformation is achieved by

– associating patterns with templates.

– Matching patterns against elements in the source tree.

– Instantiating a template to create part of the result tree.

– Separating the result tree from the source tree

(30)

XML Tech Tree

XML

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

(31)

XLink

XML application

Defines additional attributes, rules, for linking two or more XML resources

HTML Link:

XLink:

<my:baz xlink:type=„locator“ xlink:label=„buzz“

xlink:href=„foo.xml“>bar</my:baz>

<my:gogo xlink:type=„arc“ xlink:to=„buzz“/>

Use XPointer or XPath for fine-grained linking!

(32)

XPath

Common syntax and semantics for XSLT and XPointer

Addresses parts of XML document

Provides basic facilities to manipulate strings, numbers and booleans

Can also be used for matching parts of XML document (used XSLT)

(33)

XPointer

language to be used as the basis for a fragment identifier

Based on XPath

Adds arbitrary referencing inside XML documents (e.g. for continous selection with a mouse, which crosses element boundaries)

DOES NOT USE XML itself, but rather URI structure (since it will be embedded in e.g. href attributes)

<button

xlink:type="simple„

xlink:href="#xpointer(here()/ancestor::slide[1]/preceding::slide[1])">

(34)

XML Tech Tree

XML

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

(35)

XML Schema

XML language for describing and

constraining the content of XML documents

Def. „Schema“: enumeration, structure and definition of terms used to make (metadata) assertions.

XML Spec defines valid, well-formed XML Syntax. XML Schema adds (few) semantics.

(36)

DTD drawbacks

DTD

– does not support data types beyond character data

<year>Hello world!</year>

– no support for Namespaces – is (only) CF-grammar

– (DTD != XML) => XML technologies (DOM, SAX) cannot parse and expose DTD

(37)

XML Schema improvements

New built-in data types, based on SQL and Java data types

– also User-defined data types

Explicit support for namespaces

Schema constructs can be imported from existing schemas

Elements can inherit content and attributes of other elements through refinement

(38)

XML Tech Tree

XML

SGML

HTML PICS

XLink XPath

DTD

XMLQuery

XSL/T _XPointer

RDF RDF Schema

XHTML

SOAP CC/PP

P3P 2.0

PICS 2.0

XML Schema

P3P 1.0

XForms

(39)

What´s coming up?

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

(40)

The Semantic Web

Tim Berners-Lee‘s Vision

– „... the Semantic Web approach develops languages for expressing information in a machine processable form.“

Tools

– Universal Addressing Scheme (URIs) – Universal Data Format (XML)

– Ontologies (RDF, RDF Schemas)

– Object Protocols, Communication (SOAP)

Tim Berners-Lee

III. The Semantic Web

(41)

Why RDF?

„Resource Description Framework“

– Describing Resources („Things“) – Metadata – Data about Data

Metadata helps us finding things

– Yellow Pages

– Library Card Catalog

RDF is Metadata for the Web

– Structure instead of Brute-force Text Indexing or Manual Directories

(42)

Why not use XML?

There‘s more than one way to do it

^{(in XML):}

– <car color=„red“ />

– <car><color>red</color></car>

– <car color=„#cc“ />

The RDF way of things

– Resource: car – Property: color – Statement: red

RDF: <Subject> has <Predicate><Object>

(43)

RDF Core Concepts

referenced by URI

grouping possible

– Bags (unordered) – Sequences

– Alternatives

mid:192.2931C2@inf.ethz.ch

mailto:langhein@inf.ethz.ch

„Re: Ubiquitous Information Seminar“

„Wed, 31 Jan 2001 07:12:11 +0100“

„Marc Langheinrich“ „D48.2“

m:author

m:timestamp m:subject

m:realName m:office

Resource Property Statement

Application of Property with Value

Value can be

– Strings, or

– Other Resources

Uses XML namespaces

Implicitly referenced by URI

(44)

RDF/XML

RDF = Structured graphs (ER-Model)

RDF/XML = serialized RDF

– Other serializations possible, e.g. SOAP

RDF/XML

– doesn‘t look different than XML – it is XML, – but with particular data model and

– predefined set of element types

(45)

RDF/XML Example

The students in course 6.001 are Amy, Tim, John, Mary, and Sue

<rdf:RDF

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

xmlns:s="http://mycollege.edu/schema/students">

<rdf:Description about="http://mycollege.edu/courses/6.001">

<s:students>

<rdf:Bag>

<rdf:li resource="http://mycollege.edu/students/Amy"/>

<rdf:li resource="http://mycollege.edu/students/Tim"/>

<rdf:li resource="http://mycollege.edu/students/John"/>

</rdf:Bag>

</s:students>

</rdf:Description>

</rdf:RDF>

/courses/6.001

Bag

/students/Amy

/students/Tim

/students/John s:students

rdf:type

rdf:_1 rdf:_2

rdf:_3

(46)

RDF/XML Syntax

<rdf:RDF>

<rdf:Description>

– ID=string – about=#URI

– aboutEach)#URI

– abouteachPrefix=string

<x:property> ... </x:property>

<x:property resource=#URI />

<rdf:Bag>

<rdf:Seq>

<rdf:Alt>

<rdf:li>

(47)

RDF Schema

Schema definition language

Basic type system

Written in RDF

Example: Schema for RDF Schema

S S

S

S S

t t

t t t

t

t t

t

rdfs:Resource

rdfs:label

rdfs:comment

rdfs:isDefinedBy

rdfs:seeAlso

rdfs:subClassOf

rdfs:subPropertyOf rdfs:ContainerMembershipProperty

rdfs:range rdfs:domain rdfs:ConstraintProperty

rdf:type rdfs:ConstraintResource

rdfs:Class rdfs:Literal

rdf:Property t

s = rdfs:subClassOf t = rdf:type

(48)

RDF Schema Example

<rdf:Description ID="MotorVehicle">

<rdf:type resource="http://www.w3.org/2000/01/rdf-schema#Class"/>

<rdfs:subClassOf

rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>

</rdf:Description>

<rdf:Description ID="PassengerVehicle">

<rdfs:subClassOf rdf:resource="#MotorVehicle"/>

</rdf:Description>

<rdf:Description ID="Van">

<rdfs:subClassOf rdf:resource="#MotorVehicle"/>

</rdf:Description>

<rdf:Description ID="MiniVan">

<rdfs:subClassOf rdf:resource="#Van"/>

<rdfs:subClassOf rdf:resource="#PassengerVehicle"/>

</rdf:Description>

rdfs:Resource

rdfs:Class

xyz:MotorVehicle

xyz:Van

xyz:PassengerVehicle

xyz:MiniVan t

s = rdfs:subClassOf t = rdf:type

t t

t s

s

s s

(49)

RDF Applied: CC/PP

CC/PP

– Composite Capabilities/Preferences Profile – part of W3C Mobile Access Activity

– „user preferences and device capabilities“

Device Profiles

a device profile lists the (display) abilities of a particular device

Document Profiles

a document exists in different variants, each including a document profile, describing the browser support it needs to display it

Negotiate Correct Content for

Device

(50)

CC/PP

Idea

– Device sends Pointer to Device Profile along with request

– Server replies with best matching document – Device Profiles written in RDF

– UAProf Specification (WAP Forum) defines Client Capabilities for Mobile Phones

Example:

<ccpp:component>

<ccpp:Defaults rdf:resource="http://www.nokia.com/profiles/2000k" />

<uaprof:ScreenSize>640x400</uaprof:ScreenSize>

</Description>

</ccpp:component>

(51)

Needed: Infrastructure

Vocabularies

– CC/PP, P3P, PICS

Query Language

– RDF Query efforts

Data Storage

– Rdfdb, Redland

Characterization

– How much do I know?

(52)

XML Protocols Activity

XML Protocol Activity

– Since May 2000

Deliverables

– An envelope to encapsulate XML data for transfer

– an operating system-neutral convention for the content of the envelope when used for RPC

– A mechanism to serialize data based on XML Schema datatypes

– a non-exclusive mechanism layered on HTTP transport

Starting Point: SOAP/1.1

(53)

SOAP 1.1

Microsoft, IBM, et al.

– „mechanism for exchanging structured and typed information between peers in a distributed

environment using XML“

– http://msdn.microsoft.com/soap/

– part of Microsoft‘s .NET framework

Transport via HTTP

Envelope Serialization RPC

SOAP 1.1

(54)

SOAP Message Example

SOAP Envelope Framework

– what is in a message – who should deal with it

– whether it is optional or mandatory – error handling („faults“)

POST /StockQuote HTTP/1.1

Host: www.stockquoteserver.com

Content-Type: text/xml; charset="utf-8"

Content-Length: nnnn SOAPAction: "Some-URI"

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">

<SOAP-ENV:Body>

<m:GetLastTradePrice xmlns:m="Some-URI">

</m:GetLastTradePrice>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

SOAP 1.1 Message Embedded in HTTP Request

RPC Call to m::GetLastTradePrice method

(55)

SOAP Serialization

Defines XML Schema for

– Simple Types

• Strings, Integer, Floats

• Enumeration

• Byte Arrays

– Compound Types

• Structs

• Arrays

<SOAP-ENC:Array SOAP-ENC:arrayType="xsd:string[,][4]">

<SOAP-ENC:Array SOAP-ENC:position="[2]" SOAP-ENC:arrayType="xsd:string[10,10]>

<item SOAP-ENC:position="[2,2]">Third row, third col</item>

<item SOAP-ENC:position="[7,2]">Eighth row, third col</item>

</SOAP-ENC:Array>

SOAP 1.1 Array Type Example

Data Type „String“ from XML Schema

(56)

More non-W3C Stuff

ebXML (e-business XML, „SOAP+“)

– www.ebxml.org

UDDI (Description & Discovery)

– www.uddi.org

WSDL (Web Services Descr. Language)

– http://msdn.microsoft.com/xml/general/

wsdl.asp

– integrates with SOAP

CORBA/SOAP

– OMG request for proposals

(57)

No more time for:

XML Signature

– Canonical XML, Requirements (since 06/1999)

XML Encryption

– Goal: Encrypting Parts of XML (since 01/2001)

XML Query

– Requirements, Algebra & Data Model done

XForms

– replaces HTML/XHTML forms

XHTML

– XHTML 1.1 done

– now working on modularizing, XHTML 2.0

(58)

What´s coming up?

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

W3C Standards

(59)

Take Home Message

W3C

– almost 500 members, more than 1000 participants in Working Groups

The Semantic Web

– XML as universal exchange language – RDF as (weak) semantics

– SOAP et al as lightweight CORBA

– Description and Discovery Standards emerging

We‘re just getting started!!

IV. Summing Up

(60)

Building the Web of Trust

IV. Summing Up

W3C Standards

W3C Standards

What´s coming up?

 All about the W3C

 XML Technology Primer

 The Semantic Web

 Summing Up

W3C History

W3C Members

 497 members as of 01/2001

 Yearly Membership Fee

W3C Process

W3C Activities

W3C Recommendations

1 2 3

4 5

6

W3C Recommendations

1 2 3

4 5

6

W3C Recommendations

1 2 3

4 5

6

W3C Recommendations

1 2 3

4 5

6

W3C Recommendations

1 2 3

4 5

6

W3C Recommendations

1 2 3

4 5

6

W3C Domains

 Architecture

 Technology & Society Domain

 User Interface

 Web Accessibility Initiative (WAI)

W3C Activities

What´s coming up?

 All about the W3C

 XML Technology Primer

 The Semantic Web

 Summing Up

The X-Files

Other stuff

XML Activity

W3C Activities

XML Tech Tree

XML Tech Tree

XML

 markup language for documents containing structured information

 XML is not HTML

 restricted form of SGML

XML structure

 Content

 Markup

XML (cont.)

 XML Documents can be

 DTD

XML Example

XML Namespaces

XML Tech Tree

XSL

 language for expressing stylesheets, consisting of

XSLT

XML Tech Tree

XLink

 XML application

 Defines additional attributes, rules, for linking two or more XML resources

 HTML Link:

 XLink:

 Use XPointer or XPath for fine-grained linking!

XPath

 Common syntax and semantics for XSLT and XPointer

 Addresses parts of XML document

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

497 members as of 01/2001

Yearly Membership Fee

Architecture

Technology & Society Domain

User Interface

Web Accessibility Initiative (WAI)

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

markup language for documents containing structured information

XML is not HTML

restricted form of SGML

Content

Markup

XML Documents can be

DTD

language for expressing stylesheets, consisting of

XML application

Defines additional attributes, rules, for linking two or more XML resources

HTML Link:

XLink:

Use XPointer or XPath for fine-grained linking!

Common syntax and semantics for XSLT and XPointer

Addresses parts of XML document

Provides basic facilities to manipulate strings, numbers and booleans

Can also be used for matching parts of XML document (used XSLT)

XML language for describing and

Def. „Schema“: enumeration, structure and definition of terms used to make (metadata) assertions.

XML Spec defines valid, well-formed XML Syntax. XML Schema adds (few) semantics.

DTD

New built-in data types, based on SQL and Java data types

Explicit support for namespaces

Schema constructs can be imported from existing schemas

Elements can inherit content and attributes of other elements through refinement

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

„Resource Description Framework“

Metadata helps us finding things

RDF is Metadata for the Web

There‘s more than one way to do it

The RDF way of things

RDF: <Subject> has <Predicate><Object>

RDF = Structured graphs (ER-Model)

RDF/XML = serialized RDF

RDF/XML

CC/PP

Idea

Example:

Vocabularies

Query Language

Data Storage

Characterization

Microsoft, IBM, et al.

ebXML (e-business XML, „SOAP+“)

UDDI (Description & Discovery)

WSDL (Web Services Descr. Language)

CORBA/SOAP

All about the W3C

XML Technology Primer

The Semantic Web

Summing Up

W3C

The Semantic Web

We‘re just getting started!!