Two Webs!

Danny Ayers, 2007

Scripting for the Semantic Web Workshop

(“So where are the agents?”)

Web 2.0?

REST

OWL

URIsHTTP

XML

RDFWebArch

HTMLLinks

Data

The Web

href

<a href=”documentB.html”>Another Doc</a>

documentA.html

documentB.html

representation

href

http://example.org/resourceA http://example.org/resourceB

representation

href

Source : http://opte.org

The Semantic Web

http://example.org/resourceA

http://www.w3.org/2000/01/rdf-schema#seeAlso

http://example.org/resourceB

<http://example.org/resourceA> <http://www.w3.org/2000/01/rdf-schema#seeAlso>

<http://example.org/resourceB> .

resourceA resourceB

representation representation

href:resourceA

rdfs:seeAlso:resourceB

:resourceA :resourceB

representation representation

rdfs

resourceA resourceB

representation representation

href

:resourceA :resourceB

representation

rdfs:seeAlso

:resourceArdfs:seeAlso:resourceB

The Web

The Semantic Web

href

http://example.org/resourceA

representation

Resource

A Resource has a set of Representations of different (media) types [WebArch]

Rp Rp Rp

representationrepresentation

representation

mT mT mT

mediaType mediaType mediaType

mT1 = text/htmlmT2 = image/jpegmT3 = application/rdf+xml

IdealResource

Rp Rp Rp

representation representation representation

Individual representations of a resource aren't necessarily “complete”

R

Representations may change over time

Rp0 Rp1 Rp2

representationat time t0 representation

at time t1

representationat time t2

text/html text/html text/html

mediaType mediaType mediaType

<http://example.org/resourceA> <http://www.w3.org/2000/01/rdf-schema#seeAlso>

<http://example.org/resourceB> .

R

One or more of the Representations may describe a Graph [RDF]

Rp

representation

application/rdf+xml

mediaType

describes

R

Rp

representation

application/rdf+xml

mediaType

describes

Server

Client

View

ServerServer

Data Processes

Server

Client

View

Web 2.0?

Data Processes

Server

Client

DataProcesses

View

ServerServer

Tyranny of the

Browser

The Web

The Semantic Web

<a href=”documentB.html”>Another Doc</a>

documentA.html documentB.html

html:href a rdf:Property .

documentA.html html:href documentB.html .

Model

Resources

Representations

HTTP Processes

“So where are the agents?”- Jim Hendler

9thLife

Things that look like they work in virtual worlds

* Commerce (supports micropayments)

* Intellectual Property (everyone owns what they build)

* Open Source (between participants)

Source: http://home1.gte.net/pfingar/doc_mag2_f4.gif via Google Images

BehaviourRDFModel

HTTPClient

HTTPServer

Comms Bus

(The Web)

HTTPClient

Comms Bus

(The Web)View

GET /index.html HTTP/1.1Host: elsewhere.orgLink: <http://mysite.org/foaf.rdf>; rel="foaf"

<http://mysite.org/foaf.rdf#me> a :Person ;

:holdsAccount [ a :OnlineAccount ; :accountServiceHomepage <http://openid.net> ; openid:server <http://www.myopenid.com/server> ; openid.delegate <http://me.myopenid.com/"> ] .

BehaviourRDFModel

HTTPClient

HTTPServer

Comms Bus

(The Web)View

BehaviourRDFModel

HTTPClient

HTTPServer

Comms Bus

(The Web)View

What does any of this

have to do with Scripting?!

BehaviourRDFModel

HTTPClient

HTTPServer

Comms Bus

(The Web)

RDFModel

HTTPClient

HTTPServer

handle(request) {

data = model.query(request)

if(data != null){

return format(data)

}else {

other_source = model.lookup(request)

data = get(other_source, request)

}

return format(data)

Possible Issues

* need for async behaviour within request/response cycle

* system-level concurrency is unreliable?

* does messaging over HTTP even make sense?

* need for async behaviour within request/response cycle

- threads, message queues! tools are available, e.g. Quartz

* system-level concurrency is unreliable?

- the system is the Web live with unreliability!

Does messaging over HTTP make sense?

does RPC/SOAP? - occasionally (when you control both ends of the wire)

does RSS/Atom syndication? - server push can be simulated through polling

Reliable messaging can be done, e.g. HTTPLR

Semantic Web

WebDocs

SQLDBs

XMLFormats

OtherProtocols

= ConverterToRdf

BehaviourRDFModel

HTTPClient

HTTPServer

Comms Bus

(The Web)

Other Data

Semantic Web

WebDocs

SQLDBs

XMLFormats

OtherProtocols

= ConverterFromRdf

Model

Resources

Representations

HTTP Processes

One Web!

http://talis.com

Semantic Web Application Platform

Thank you!

These slides online :http://dannyayers.com/sfsw2007/slides