Open Archives Initiative Protocol for Metadata Harvesting: a low-barrier HTTP/XML protocol that allows a 'data provider' system (typically a repository or CRIS) to expose its metadata records for incremental harvesting by 'service providers' (aggregators, search services, national portals).

ByCASRAI Editorial Board

· Last updated 10 Jul 2026

Examples

Worked examples

Is an instance
BASE harvesting Dublin Core metadata via OAI-PMH from thousands of repositories.
Is an instance
OpenAIRE harvesting CERIF-XML from European CRIS systems via OAI-PMH.

Counter-examples

Looks similar, but isn't

Not an instance
A simple RSS feed of new items is not OAI-PMH (no resumption-token semantics, no set selection).
Not an instance
A REST API returning JSON is not OAI-PMH unless it also offers the OAI-PMH XML protocol.

Editorial commentary

OAI-PMH (current version 2.0, 2002) defines six verbs (Identify, ListMetadataFormats, ListSets, ListIdentifiers, ListRecords, GetRecord) over HTTP GET, with responses in XML. The protocol is metadata-format-agnostic: Dublin Core is mandatory, but CERIF-XML, MODS, RIOXX, JATS, and many others can be exposed in parallel. Despite being twenty years old, OAI-PMH remains the dominant repository-harvesting protocol in research-information ecosystems, including OpenAIRE harvest, BASE, CORE, and national aggregators.

References

Lagoze C., Van de Sompel H., Nelson M., Warner S., 'The Open Archives Initiative Protocol for Metadata Harvesting, Version 2.0' (openarchives.org/OAI/openarchivesprotocol.html), 2002.

Also known as

Open Archives Initiative Protocol for Metadata Harvesting

Machine-readable encodings

Use in your systems

JATS XML <role> element

xml

<role vocab="credit"
      vocab-identifier="https://casrai.org/dictionary/"
      vocab-term="OAI-PMH"
      vocab-term-identifier="https://casrai.org/dictionary/term/oai-pmh" />

Schema.org DefinedTerm (JSON-LD)

json

{
  "@context": "https://schema.org",
  "@type": "DefinedTerm",
  "@id": "https://casrai.org/dictionary/term/oai-pmh",
  "name": "OAI-PMH",
  "identifier": "https://casrai.org/dictionary/term/oai-pmh",
  "description": "Open Archives Initiative Protocol for Metadata Harvesting: a low-barrier HTTP/XML protocol that allows a 'data provider' system (typically a repository or CRIS) to expose its metadata records for incremental harvesting by 'service providers' (aggregators, search services, national portals).",
  "inDefinedTermSet": "https://casrai.org/dictionary/domain/research-info-systems#set",
  "url": "https://casrai.org/dictionary/term/oai-pmh",
  "sameAs": [
    "Open Archives Initiative Protocol for Metadata Harvesting"
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "publisher": {
    "@id": "https://casrai.org/#organization"
  },
  "dateModified": "2026-07-10T02:06:20",
  "inLanguage": "en"
}

Referenced across the research world

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