Ithaca, NY & Los Alamos NM—The Open Archives
Initiative is pleased to release version 2.0 of the Open Archives
Initiative Protocol for Metadata Harvesting (OAI-PMH). The release of OAI-PMH
v.2.0 comes after 16 months of worldwide experimentation with version 1.x
of the protocol, an 8 month revision process by the OAI-tech group, and 4
months of alpha/beta testing. Thanks to this rigid testing and revision,
we feel confident to release the OAI-PMH version 2.0 as a stable
Summary of changes in version 2.0
- Clarifications and Specification Cleanups.
- Core Protocol versus Extensible Notions. A clear boundary
has been established in between the core OAI-PMH protocol and
ancillary concepts, by separating the protocol specification from a
newly introduced Implementation Guidelines.
- Clarified Data Model. The protocol now builds on a
well-defined “resource – item – metadata-record” data model,
correcting a level of ambiguity that existed with this respect in
- Dublin Core Metadata Definition. In a successful and
trend-setting collaboration with the Dublin Core Metadata Initiative,
an XML Schema for unqualified Dublin Core has been created, which is
hosted by the DCMI and used in the delivery of metadata in the
mandatory DC format in the OAI-PMH.
- Single XML Schema for OAI-PMH Responses. OAI-PMH now
defines a single XML Schema to validate responses to all OAI-PMH
- Language Cleanup. The OAI-PMH now uses the notions must,
must not, may, should, etc. as in RFC2119, allowing for a better
understanding of protocol conformance.
- Error Corrections.
- Uniform Date and Time Encoding. Dates and times are now
uniformly encoded using ISO8601 and are expressed in UTC throughout
- Flow Control Idempotency. In order to address known
problems with harvesting large datasets, the new protocol clearly
defines and mandates the idempotent nature of resumptionTokens,
providing deterministic behavior in the face of data transmission
- New Functionality.
- Multiple Time Granularity. In response to requests
originating mainly from the union-catalogue realm, the OAI-PMH now
supports harvesting at different levels of time-granularity: support
of day granularity is mandatory, while support for seconds granularity
- Error Reporting. Version 2 introduces a new error reporting
mechanism, clearly separating between errors occurring at the HTTP
transport layer used by the OAI-PMH and errors at the OAI-PMH level.
- Enhanced Identify Semantics. The response to the Identify
request is more expressive than in Version 1.x, providing more
information to harvesters and supporting multiple harvesting
- Item Set Membership. For repositories that support
set-structures, it is now mandatory to list set membership of items in
the responses to the GetRecord, ListRecords and ListIdentifiers
- Related Changes and Activities.
- Implementation Guidelines. Implementation Guidelines
documents are provided to support interpretation of the protocol
document by implementers of repositories, harvesters, aggregators,
mirrors, caches, etc.
- Friends Schema. The usage of a “friends” XML Schema at the
level of the Identify-response is recommended to help establish a
dynamic approach to the process of discovering repositories.
- Provenance Schema. The usage of a "provenance" XML Schema
is recommended at the level of the "about" container attached to
metadata records, in order to describe the provenance of exposed
metadata, and support deduplication of metadata harvested from
- Branding Schema: An XML Schema for usage at the repository
or set-level is provided to facilitate branding and rendering of
harvested metadata in third party services.
- MARC XML: The usage of the MARCXML Schema released by the
Library of Congress (June 2002) is recommended over the usage of the
oai_marc Schema that was introduced with the release of version 1.0 of
- Identifiers: The specification for the optional oai-identifier
scheme for uniquely identifying items in a repository now relies on
dns-names instead of registered repository-identifiers to achieve
Strategy for transition from OAI-PMH 1.1 to 2.0
The OAI registration service for data providers is ready to accept
registration of 2.0 conformant repositories at
http://www.openarchives.org/data/registerasprovider.html. On September 1st 2002, registered sites that have not upgraded to
version 2.0 will be sent a reminder that they must upgrade. As of this
date, attempts to register with the OAI registration service must conform
to OAI-PMH version 2.0. On December 1st 2002, repositories that have not upgraded to 2.0 will be
removed from the OAI registry.
Essential links to information about the release
Links to version 2.0 tools.
This release is a good opportunity to acknowledge institutions and individuals who have
significantly contributed to the remarkable endeavor that started with
the first Open Archives Meeting in 1999 in Santa Fe and that led to this
official release of the OAI-PMH v.2.0 protocol.
For long-term financial support of OAI activities and
- Coalition for Networked Information
- Digital Library Federation
- National Science Foundation
For financial support and support-in-kind of various OAI
- Cornell University
- Council on Library and Information Resources
- Dublin Core Metadata Initiative
- Library of Congress
- Los Alamos National Laboratory
- Andrew W. Mellon Foundation
For participation in the development of the OAI-PMH and
OAI support activities:
firstname.lastname@example.org & Herbert Van de Sompel;
email@example.com. The OAI