OAI-PMH

Protocol description

The OAI-PMH protocol is a way of exchanging metadata between institutions over the Internet in order to widen access to digital documents.

It can be used to:

• increase the visibility of digital collections on the Internet;
• virtually rebuild corpora from resources accessible on various sites;
• populate topic-based portals.

It can be freely used, as can its specifications, which are available from www.openarchives.org.

OAI-PMH defines two types of stakeholders:

• data providers, who place their metadata on a web server known as a repository;
• service providers, who harvest this data and add it to the indexes of their own digital libraries.

A single institution may play both these roles, both publishing metadata and harvesting metadata provided by other institutions.

The OAI-PMH protocol’s basic operation is based on a client-server communication model. The client sends http queries to the server, and the server responds with an XML data feed.

BnF’s OAI repositories

Another way of accessing data

The Bibliothèque nationale de France has opened two OAI repositories aimed at facilitating access to its collections and data.
The first of these, OAI-NUM, contains the records for all documents digitized by the BnF and accessible via the Gallica digital library. However, it does not contain the records for the documents from partner libraries which are accessible via the Gallica digital library.
The second, OAI-CAT, is intended to contain records for all BnF documents, whether digitized or not. It currently contains over eleven million records.

These two repositories are organized into sets of records:

• by document type
• by topic-based file or collection in accordance with the structure used to organize collections
• by subject index under the Dewey Decimal Classification system

They are regularly added to, can be freely harvested under the terms of the OAI-PMH protocol, and enable digitized documents and bibliographic data produced by BnF to be referenced in other databases.