NBN:URN Generator and Resolver

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NBNURN Generator and Resolver

• ERPANET Workshop on Persistent Identifiers
• Cork, 17-18 June, 2004.
• Ádám Horváth
• National Széchényi Library
• Hungary

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Contents

• Preparation
• Protocol
• Design principles
• NBNURN generation
• NBNURN resolution
• The web interface
• Technical background
• Intended users

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Preparation

• Studied the relevant standards
• http//www.uri.net/
• Studied the existing implementations
• Finnish
• Norwegian
• German

4
Protocol

• THTTP protocol (RFC 2169)
• Implemented features
• N2L
• N2LS
• L2N

5
Design principles

• Simplicity
• User friendly generation
• Administration free
• Reliability
• The uniqueness of URN is guaranteed
• Only the owner of the document can request a URN

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The owner of the document

• Who is the owner?
• Who has the right to write into the document
• Advantages
• Simple
• Can be automated
• There is no problem with passwords

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Requesting URN - Step 1

• HTTP request
• http//nbn.oszk.hu/GetNBN?urlhttp//solanum.oszk.
  hu/proba.html
• The server checks
• Does the document exist?
• Is it an HTML document?
• Is there already a URN for this document?
• Has anyone placed a transaction for it?

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Requesting URN - Step 1 (contd)

• Answer
• The server place the request
• OK0urnnbnhu-3006tid3291d4fcf5b5fce1d0
• Error-9 Error message

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Requesting URN - Step 2

• Writing the URN into the document
• It is the requesters task
• ltheadgt ... ltmeta name"dc.identifier
  scheme"urn content"urnnbnhu-3006"gt ...
  lt/headgt

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Requesting URN - Step 3

• Finalizing the request
• http//nbn.oszk.hu/GetNBN?urlhttp//solanum.oszk.
  hu/proba.htmlurnurnnbnhu-3006tid3291d4fcf5
  b5fce1d0

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Requesting URN - Step 3 (contd)

• The server checks
• Has the request already been placed
• Does the document exist
• Is it an HTML document
• Does it contain the URN
• Answer
• OK
• Error message

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Resolving URN

• N2L (URN to URL)
• HTTP request
• http//nbn.oszk.hu/N2L?urnnbnhu-3006
• HTTP coded answer
• 303 (SEE OTHER) redirects to the appropriate
  URL.
• 404 (NOT FOUND) if the URN does not exist

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Resolving URN (contd)

• L2N (URL to URN)
• HTTP request
• http//nbn.oszk.hu/L2N?http//solanum.oszk.hu/prob
  a.html
• HTTP coded answer
• Text (eg. urnnbnhu-3006).
• 404 ( FOUND) if it does not exist.

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Resolving URN (contd)

• N2Ls (URN to URLs)
• HTTP request
• http//nbn.oszk.hu/N2Ls? urnnbnhu-3006
• HTTP coded answer
• HTML page with a list of URLs
• text/uri-list MIME type (if explicitly
  requested).
• 404 ( FOUND) if it does not exist.

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Other functions

• Changing the URN - URL assignment
• This is also a three step process
• The document must exist in both the old and the
  new URL
• Deleting the URN - URL assignment
• This is also a three step process
• The document itself can only be deleted after the
  deletion of the URN - URL assignment

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Other functions (contd)

• Request and modification for dynamic pages
• http//nbn.oszk.hu/GetNBN?urlhttp//solanum.oszk
  .hu/proba.htmlnocheck1
• Server
• Does not check the existence of the document

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Other functions (contd)

• Bulk generation of URNs is also possible
• Sample scripts written in Python are provided for
  the users

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Web interface

• The functions can be invoked from a web interface
• Test request is also possible
• The interface is bilingual Hungarian and English
• The web interface also contains background
  material user guide, the source of the
  application, sample script etc.

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Technical background

• PHP for the interface
• Java servlets for the functions
• PostgreSql is the database
• It is an open source application

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Intended users

• Hungarians
• How can we ensure this
• Only the Hungarian interface works on the
  production database
• The English interface works on the development
  database. The purpose of the English interface is
  to make our results more widely available.

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Guidelines for the request

• Copies of the same object should have the same
  URN
• Different versions of the same object, e.g. in
  MS Word and HTML shall have different URNs.
• If an object is changed, a new URN only needs to
  be assigned if the intellectual content of the
  object changes. Editorial changes (e.g. changes
  to fonts etc.) do not necessitate a change of URN.

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Resolving URN in the OPAC

• We build a database on the THTTP resolvers.
• The OPAC display program consults with this
  database and sends the URN to the appropriate
  resolver.

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Thank you for your attention

• adam_at_oszk.hu