Beyond OAI-PMH

May 29, 2011 in SessionIdeas

C & NW RR, a general view of a classification yard at Proviso Yard, Chicago, Ill. (LOC)

OAI-PMH is a great way to ship large "collections" of records between repositories.

The Open Archives Initiative – Protocol for Metadata Harvesting (OAI-PMH) is the foundation on which the IMLS Digital Collections and Content project and the companion Opening History aggregation are built.* Although small increases in the use of OAI-PMH were seen over the course of the project, less than a quarter of IMLS National Leadership grant projects provide item-level metadata using OAI-PMH [1, 2]. In some cases, the projects in the the missing 75% are legitimate – they are not collection with readily available item-level metadata (e.g. narrative exhibits, interactives/games, etc.). But this still leaves many projects/collections out of a broader network of resources. OCLC/RLG found a higher percentage (48%) of member organizations using OAI-PMH, but it is unclear how much of their metadata was shared this way [3]. While recognizing that OAI-PMH has been successful at making millions of descriptions available, it’s worth pausing to wonder if 25-50% adoption is good enough.

In light of the rapid growth of LOD in the last few years, I’ve been wondering how a large-scale aggregation like IMLS DCC might fit into this environment. Here are a few questions to discuss at #LODLAM:

  • What are the lessons from OAI-PMH that will be important for LOD-LAM?
  • How is the lack of one, common protocol for sharing data a benefit and/or a danger?
  • Will Linked Open Data be “low barrier” for some, but untouchable for many?
  • Can/should we build LOD on top of existing OAI-PMH installations? (see [4, 5])
  • Should we abandon OAI in favor of more web-friendly approaches? (See @edsu Digital Public Library as a Generative Platform)
  • What are the lessons from the Museums and the Machine-Processable Web and Europeana for U.S. organizations?
  • One of the reasons that OAI-PMH succeeded was through support of funders – what should funding agencies tell projects about implementing LOD?
Nottingham School at the Interstates edge," in Teaching & Learning Cleveland

LOD offer the opportunity to move smaller units of information, quickly, to more access points.

  1. Palmer, C., Zavalina, O., Mustafoff, M. (2007) Trends in Metadata Practices: A Longitudinal Study of Collection Federation. pre-print available at:
  2. Jett, J.G. (2010). Supplementing OAI-PMH in the IMLS Digital Collections & Content Aggregation. Masters Thesis. Available at:
  3. Ayers, L. , Camden, B. P. , German, L. , Johnson, P. , Miller, C. and Smith-Yoshimura, K. (2009) What we’ve learned from the RLG partners metadata creation workflows survey— Retrieved March 2, 2009 from
  4. Haslhofer, B., & Schandl, B. (2008). The OAI2LOD Server: Exposing OAI-PMH metadata as linked data. International Workshop on Linked Data on the Web (LDOW2008), co-located with WWW. Available at:
  5. Haslhofer, Bernhard and Schandl, Bernhard (2010) Interweaving OAI-PMH Data Sources with the Linked Data Cloud. Int. J. Metadata, Semantics and Ontologies, 1 (5). pp. 17-31. Available at:


* Disclaimer: these opinions are my own and may not reflect official opinions of the project or my colleagues.

This post has been cross-posted on Inherent Vice.

4 responses to Beyond OAI-PMH

  1. It seems like the work of OAI-PMH should be leveraged for LOD-LAMs, unless someone can explain why this would be a drawback. The question, for me, is how do we leverage collections that have no normalization?

    Greatly looking forward to talking with you at LOD-LAM!!

  2. Hi Jenel,

    I give OAI-PMH three stars according Sir Tim’s rating scale – not bad for a start. Some of what needs to change must happen behind an OAI-PMH provider – like creating links to other LOD, using shared properties, etc.
    The bigger problem is that OAI-PMH is so tightly tied to a simple Dublin Core XML schema that is not aligned with current DCMI recommendations and cannot handle alternative serialization formats (JSON, Turtle, etc.). (I recognize that other XML standards can compliment the simple DC, but the simple DC requirement doesn’t go away).

    Despite the amount of adoption it has seen, PMH development has largely been abandoned. As @reporat suggests, some kind of maintenance plan is needed to move forward. I think that is part of the conversation I’d like to have at LOD-LAM.

    • @Urban,

      All the same about the legacy of PMH. But Is there a Plugin for WP which would implement OAI_DC to make the site a resource for a PMH crawler?

  3. Good idea, Richard. In fact, it would be great to create a plan for all library standards. It seems like they should be leveraged.

    Look for me in the Kabuki bar tonight!

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