29

May 2

00

7

Pete Johnston, Eduserv Foundationpete.johnston@eduserv.org.uk

www.eduserv.org.uk/foundation

Some thoughts on Compound Objects & Graphs

OAI ORE Technical Committee Meeting, New York City

29 May 2007OAI ORE Technical Committee Meeting, New York City, USA

2

Some thoughts on Compound Objects & Graphs

• Graph or graphs?

• So which graph do I need?

Title slide photo of Brooklyn Bridge by Flickr user smcgeeSee http://www.flickr.com/photos/smcgee/351136186/

29 May 2007OAI ORE Technical Committee Meeting, New York City, USA

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Graph or graphs?

part part

Composite X

Document A Document B

Doc-AHTML

Doc-APDF

view

view Doc-B

HTML

view

partpart

Document C Document D

view

view

view

view

Doc-CHTML

Doc-CPDF

Doc-DHTML

Doc-DPDF

ore:hasView

ore:hasView

Composite:X

http://example.org/graph/1

Graph 1?

Doc:A

Doc:D

Doc:B

ore:hasPart

ore:hasPart

Doc:AHTML

ore:hasView

ore:hasView

ore:hasPartDoc:C

Doc:APDF

Doc:BHTML

ore:hasView

ore:hasPart

Doc:CHTML

ore:hasView

Doc:CPDF

Doc:DHTML

ore:hasView

Doc:DPDF

ore:hasView

ore:hasView

Composite:X

http://example.org/graph/2

Graph 2?

Doc:A

Doc:D

Doc:B

ore:hasPart

ore:hasPart

Doc:AHTML

ore:hasView

ore:hasView

ore:hasPartDoc:C

Doc:APDF

Doc:BHTML

ore:hasView

ore:hasPart

Doc:CHTML

ore:hasView

Doc:CPDF

Doc:DHTML

ore:hasView

Doc:DPDF

ore:hasView

ore:hasView

Composite:X

http://example.org/graph/3

Graph 3?

Doc:A

Doc:D

Doc:B

ore:hasPart

ore:hasPart

Doc:AHTML

ore:hasView

ore:hasView

ore:hasPartDoc:C

Doc:APDF

Doc:BHTML

ore:hasView

ore:hasPart

Doc:CHTML

ore:hasView

Doc:CPDF

Doc:DHTML

ore:hasView

Doc:DPDF

Composite:X Composite:Yore:isPartOf

http://example.org/graph/4

…and Graph 4? (different creator/authority/provenance?)

Composite:Y Composite:Xore:hasPart

http://example.org/graph/5

…or Graph 5?

29 May 2007OAI ORE Technical Committee Meeting, New York City, USA

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So which graph do I need?

29 May 2007OAI ORE Technical Committee Meeting, New York City, USA

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Compound objects and graphs

• Compound object and graph are distinct resources, identified by distinct URIs

• Single object - multiple graphs?– Different purposes/contexts?

• Graph discovery– Links in representation of object (in HTTP header or in e.g. HTML)– Content negotiation– (Sitemaps etc)

• If multiple graphs may be provided then– “Provider” can’t depend on serving single graph as representation of

object?– But could serve “graph list”?

• If multiple graphs provided, how does consumer decide which graph to use?

– Metadata describing graph?

29 May 2007OAI ORE Technical Committee Meeting, New York City, USA

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Examples etc

• Examples– http://www.incognitum.net/petej/projects/oaiore/e

xamples/20070521/

• e.g. Doc 2– http://www.incognitum.net/petej/projects/oaiore/e

xamples/20070521/doc2/

• Berners-Lee’s Tabulator– http://dig.csail.mit.edu/2005/ajar/ajaw/tab

• Dave Beckett’s Triplr– http://triplr.org/rdf/http://www.incognitum.net/pet

ej/projects/oaiore/examples/20070521/doc2/

29

May 2

00

7

Pete Johnston, Eduserv Foundationpete.johnston@eduserv.org.uk

www.eduserv.org.uk/foundation

Some thoughts on Compound Objects & Graphs

OAI ORE Technical Committee Meeting, New York City