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.