1 / 15

OCLC Open Source Linked Data Framework

OCLC Open Source Linked Data Framework. Ralph LeVan Sr. Research Scientist OCLC Research. Goal: Expose Text Database Content as Linked Data.

yale
Download Presentation

OCLC Open Source Linked Data Framework

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. OCLC Open Source Linked Data Framework Ralph LeVan Sr. Research Scientist OCLC Research

  2. Goal: Expose Text Database Content as Linked Data • Technique: Using a combination of the urlrewritefilter from tuckey.org, the content negotiation component from the Freie Universität Berlin’s Pubby server and our Open Source SRW/U server you can expose the records in your database as Linked Data

  3. Roadmap • SRW/U Server • URIs for records • Real World Objects for records • Multiple record formats • RDF needs to be returned • Content Negotiation

  4. SRW/U Server • SRW/U server sits in front of text databases • We have interfaces for DSpace, Lucene and Pears • Easy to write your own interface • Convert CQL query to native query language • Do search and return a resultset object • Return records from the resultset • (The Lucene interface is a good simple example of how to build your own database interface) • I expose my SRW/U service as <context>/search, but you can put it wherever you want.

  5. URIs for records • urlrewritefilter implements apache mod_rewrite patterns for java servlets • It sees the URI and converts it to an SRU search. • <from>^/([0-9][0-9]+)/$</from> <to>/search?query=local.viafID+exact+%22$1%22</to> • E.g. viaf/123 becomes viaf/search?query=viafID+exact+%22123%22

  6. Aside: What to Return? • An SRU query returns a searchRetrieveResponse. A smart client can pick its record out of that response, but that seems wrong • A bad URI will result in “no records found”, but a 404 (record not found) is more appropriate • Solution: add a new parameter (service=APP) to signal that this was a request for a single record • E.g. viaf/123 becomes viaf/search?query=viafID+exact+%22123%22&service=APP

  7. Real World Objects for records • urlrewritefilter can generate 303 (see other) redirects based on URI patterns • <from>^/([0-9][0-9]+)$</from> <to type="seeother-redirect">/viaf/$1/</to> • E.g. viaf/123 redirects to viaf/123/ • The target, viaf/123/, is called the Generic Record • (note: now we use viaf/123/ as the URI that gets turned into the SRU search)

  8. Multiple record formats • urlrewritefilter plus the new httpAccept parameter in SRU • E.g., viaf/123/marc21.xml becomes viaf/search?query=viafID+exact+123&httpAccept=application/marc21+xml • SRU is configured with a list of supported media types and the XSL stylesheets that render them

  9. MimeType Configuration • XML.mimeTypes=application/sru+xml;q=0.85, application/xml, text/xml • HTML.mimeTypes=text/html;q=0.9, application/xhtml+xml • RSS.mimeTypes=application/rss+xml;q=0.8 • RSS.styleSheet=viaf2rss.xsl • M21.mimeTypes=application/marc21+xml;q=0.7 • M21.styleSheet=viaf2marc21.xsl • marc21HTML.mimeTypes=application/marc21+html;q=0.7 • marc21HTML.styleSheet=viaf2marc21.xsl

  10. Aside: 123/marc21.xml NOT 123.m21 • The Generic Record being at viaf/123/ seems to imply that it is a collection of records • How do I ask for the HTML version of the MARC21 version of viaf/123 if suffix mangling is all I have?

  11. RDF needs to be returned • viaf/123/rdf.xml • Making good RDF is tricky and beyond the scope of this presentation (but I think we’re getting close to agreements of sensible basics)

  12. Content Negotiation on Generic Record • Pubby has a really nice Content Negotiation module • It is configured with the list of supported media types with optional quality measures • It takes an HTTP Accept header and returns the supported media type that matches best • SRU is configured with a list of supported media types and their quality measures and the XSL stylesheets that render them (see previous slide)

  13. Result • viaf/123 redirected to viaf/123/ • viaf/123/ turned into viaf/search?query=viafID+exact+123 • VIAF record returned by SRW/U server • Content Negotiation causes viaf/123/viaf.html to be returned to googlebot and browsers, viaf/123/rdf.xml to applications that ask for application/rdf+xml and viaf/123/viaf.xml returned when no preference is provided

  14. Lucene Database Demonstration • TBD

  15. Questions?

More Related