Representing URI Resolution in OWL

1
Representing URI Resolution in OWL

• Alan Ruttenberg (responsible for errors)
• Matthias Samwald
• Jonathan Rees

2
What goes wrong with URLs

• The server disappears (s)
• The content disappears - 404 (c)
• The content might change and you want to know and
  communicate what it used to be (d)
• Access to the content is too slow (s)
• Access to the content is too public (p)
• The content is very big (b)
• You don't know if a URI is an information
  resource or not (w)
• You want to record and access metadata -
  information about some information resource - and
  you don't know where to get it. (m)
• You don't know what format an information
  resource is encoded in. (f)

3
Existing proposals LSIDs

• Authority
• Location independence
• Data/Metadata distinction
• Access method independence
• Versioning
• (similar ARK, purl, DOI)

4
Existing proposals http-range14

• Use http.
• Use result code to recognize potential
  non-information resources
• Result code 2xx information resource
• Result code 3xx any resource, pointer to more
  information
• Result code 4xx unknown type
• 303 to get more information about the thing

5
Existing proposals Content negotiation

• Agent asks for resource
• Server responds with list of content types and
  where to get each
• Agent chooses which to retrieve

6
Short statements

• John Barkley
• Identify MIME Types of URIs.
• Identify versions of URIs
• URIs should dereference to something, even if it
  is only documentation,e.g., rdfscomment
• Use LSIDs

7
Short statements

• Phil Lord
• URIs should identify one thing only.
• URI allocation schemes should encourage stability
  over time.
• Resources identified by URIs should be
  checksummable.

8
Short statements

• Matthias Samwald
• Be careful what you are talking about - use
  separate names
• Distinguish information resource from
  non-information resource
• Distinguish making a query from resolution

9
Short statements

• David Booth (Information resources/metadata)
• http//example.org/foobar might identify a
  thing(non-information resource),
  http//example.org/foo can be used to seek
  metadata about it.
• Dereferencing non-information resources yields a
  http 303 result code

10
Selected issues with proposed solutions

• http-range14 - late dont know anything until
  you do the retrieval
• Content negotion - confusion over what the thing
  is - e.g. foaf human readable document, rdf at
  same address. Try talking about the ugly font.
• LSID - requires server deployment. Based on web
  services (slow). Unclear semantics of versions,
  metadata, data
• No single proposal deals with all issues

11
An Alternative

• Use the our SW tools to help solve this problem
• Represent the information that you want to know
  about URIs in OWL.
• Build an ontology to represent consensus/schema.
• Take advantage of consistency checking,
  inheritence

12
Goals

• Transparent/explicit. Contract based.
• Adjustable
• Extendable
• Ontologically sound

13
Different things

• The temperature of a patient (not an information
  resource)
• A instrument that measures and reports
  temperature (not an information resource)
• The record retrieved when you query the
  instrument (an information resource)
• The record that you retrieved at a certain time
  and you copied and saved (an information resource)

but related
14
A sketch

• Some useful distinctions
• Top level classes
• Some properties
• Only about instances (not properties or classes)

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InformationResource NotAnInformationResource

• Information resources are conceptually Gettable
• They might not be able to be retrieved at a
  particular time
• They might change
• Ask yourself Would it be possible to get the
  thing itself over a network
• Disjoint

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UnchangingInformationResourceEvolveableInformatio
nResource

• UnchangingInformationResource is like LSID
  data. A promise is made that the content will
  never change.
• EvolveableInformationResource are resources that
  might change (even if we dont want them to, e.g.
  NCBI gene records)
• Disjoint

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RetrievalMethod

• A way to get an information resource.
• Some examples
• StandardURIRetrieval
• TransformUriRetrieval http//genesdbs.org/entrez/7
  157 gt http//cache.ibm.com/?generetrieveidhttp
  //genesdbs.org/entrez/
• SPARQLMethod gt http//genesdbs.org/entrez/7157
  gt
• select ?dataFROM http//sparql.ibm.com/lifesci
  WHERE http//genesdbs.org/entrez/7157 data
  ?data
• WebServiceMethodSupply a WSDL, name of parameter

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RetrievalMethod (notes)

• There may be more than one.
• When more than one try them all in random order,
  or explicitly represent preference.
• For company specific retrieval, add another
  RetrievalMerthod to an appropriate upper class
  (one more triple)

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InformationResourceFormat

• Explicitly give enough information to know what
  you will have to parse should you retrieve the
  resource (so you can choose whether or not to
  retrieve)
• Like mime/type - BUT only the format, not the
  type (thats for defining by class)
• RDFXML
• RDFTurtle
• JPEG
• TIFF
• HTML
• Note Different formats of same digital thing
  should be given different names. (but they may be
  related by some property, e.g. hasOtherRepresentat
  ion)

20
Some classes of InformationResource

• XrayImage
• Triples (rdf statements)
• MedicalRecord
• VersionInformation
• ProtocolDocumentation
• ProvenanceDescription
• SPARQLEndpoint
• .
• (ask me about metadata!)

21
Properties

• Relate a NotInformationResource to an
  InformationResource - seeAlso, subjectOfMedicalRec
  ord, foafhomepage, biozend-data (described by
  data)

22
Properties

• Relating an informationResource to metadata
• previousVersion (UnchangingInformationResource)
• hasVersionDescription
• hasChangeDescription
• generatedBy (not an information resource)
• cachedDate
• hasMD5 (UnchangingInformationResource)

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An example
Class PartnersDigitalXray subclassOf
NeverChangingInformationResource subclassOf
DigitalXray mediaType hasValue jpegType
retrievalmethod hasValue webServiceMethod1002
http//partners.org/radiology/817277366 rdftype
PartnersDigitalXray mediaType jpegType
(inherited) retrievalmethod webServiceMethod1002
(inherited)
24
Sharing bare URIs

• Dont, unless you have to. Generally messages
  should be a set of triples giving adequate
  information about type, resolution
• If you do, use existing best practices to make
  them last, e.g. PURL