Flink: Lessons of

interoperability

Peter Mika Dept. of Business Informatics

Free University Amsterdam http://www.cs.vu.nl/~pmika/

1st Intl. Workshop on Interoperability of SW portals

Content

Flink Interoperability Flink + Interoperability

What is Flink?

Flink is a directory of Semantic Web research Browse the social network of all authors at ISWC ‘01-’04 Profiles with personal information, emails, publications View statistics Download profiles in FOAF format Export for Social Network Analysis

Demonstration of latest SW technology 1st prize at the Semantic Web Challenge (2004) Open source (soon) Try it!

http://flink.semanticweb.org

Technology highlights

Social network mining from the Web and other legacy sources (emails, publications)

Social networks based ontology extraction Collection of FOAF data from the SW (“scuttering”) Aggregation and identity reasoning (“smushing”)

Custom inferencing using Sesame OWL use

sameAs, inverse functional properties Web Service integration

geographic lookup WML interface …

JUNGNetwork API

Semantic Web Web

Sesame

FOAF profiles

Web mining

Emails

IMAP or

POP3

Sesame Sesame Sesame

Publications

GoogleScholar,Bibster

Network analysis

Web application

RDF storage

Sesame

Metadata enrichment (Identity reasoning, geographic lookup)

Interoperability (1)

Interoperability on the knowledge level =

syntax + semantics + context Syntax

Easy (but a ‘forgiving’ parser would be nice)

Semantics Doable: shared ontologies, ontology mapping (e.g. for

foaf:interests), unique object identification (e.g. for foaf:Person),

Context Challenge

Interoperability (2): Context

Provenance: where the information comes from, when was it collected?

Time-to-live: how long is it going to stay valid?

Trust and ratings: is it considered trustworthy (by someone), is it important (for someone)?

Security: who can access it and how? …

Interoperability (3):Process

How do we find each other? Registries vs. pointers

How do we exchange? Connectivity Protocol (e.g. subscriptions vs. advertizements)

What do we exchange? Files, access etc.

Why would we exchange? The economics

Flink and the FOAF-web

Flink interoperates with the FOAF-web Producer and consumer of FOAF data But: 762 other definitions of Person (

www.swoogle.org), including swrc:Person FOAF-web is the kind of nightmare the SW

promises to be Open, decentralized system Distributed data and services Issues of syntax and semantics Lack of authority, privacy etc.

Flink and the FOAF-web (2)

Majority of files are incorrect XML, RDF or FOAF Errors from the obvious to the sneaky e.g. <foaf:mbox_sha1sum /> Ignore

FOAF extensions What to do with them? Ignore on import, don’t export

FOAF interests? A ‘loose end’ in FOAF (like dc:Creator) Ignore (on import)

Who is right? Let the user decide

How to contact Dan Brickley?

Summary

Interoperability is a challenge: Knowledge: syntax + semantics + context Process

Interoperability is about coming to an agreement Realize the trade-off between level of

commitment vs. scale