Announcement: The operation of NSDL has been transferred to ISKME's OER Commons (effective December, 2014) - Read the news release.
This documentation describes the policies, procedures, and services that existed while NSDL was operated by UCAR.
For the NSDL to successfully harvest your metadata, your OAI Repository must be compliant with the OAI-PMH version 2.0 specification, so please read the specification carefully [http://www.openarchives.org/OAI/openarchivesprotocol.html].
Minimally, you will need a basic understanding of:
We also recommend familiarity with the Guidelines for Repository Implementers [http://www.openarchives.org/OAI/2.0/guidelines-repository.htm].
Each of the following details needs to be implemented correctly in order to have successful OAI metadata harvesting.
In all OAI-PMH responses, the responseDate value must be the time and date of the OAI server's response in UTC. This must be encoded using the "Complete date plus hours, minutes, and seconds" variant of ISO8601: YYYY-MM-DDThh:mm:ssZ. Note the Z at the end, which implies UTC (meaning Greenwich Mean Time, more or less). Example: 2003-10-24T14:05:27Z
The email address(es) indicated in the Identify response should be valid and messages sent to them should be seen by the appropriate individual(s).
The granularity indicated in the Identify response must match the granularity of the datestamp value in served records. That is, if your OAI server supports seconds granularity, then the datestamp value in served records must include seconds (in ISO8601 UTC, of course).
OAI identifiers uniquely identify an OAI item. Conversely, each OAI item must be uniquely identified by an OAI identifier. An OAI item may have multiple metadata formats and the metadata may be updated from time to time. Updates will change the datestamp in the OAI header, but the OAI identifier will remain the same. OAI-PMH says that identifiers must be URIs. We recommend following the Guidelines for OAI Identifiers [http://www.openarchives.org/OAI/2.0/guidelines-oai-identifier.htm] We do not recommend the use of URLs for OAI identifiers.
All metadata formats served must be indicated, and for each format served, the appropriate XML namespace and XML schema are given, both in the ListMetadataFormats response and in the metadata records themselves. Note that the OAI-PMH element/field/argument "metadataPrefix" is different from the XML prefix. This means
The OAI Repository Explorer has a facility to check schema validity of single XML responses [see lower right of the html page at http://oai.dlib.vt.edu/cgi-bin/Explorer/oai2.0/testoai].
This is required by the OAI specification, and is necessary to allow incremental harvests (of any metadata changed since a particular date). Here's how to test:
We recommend using resumptionTokens if you need to serve more than 2 megabytes of metadata. If you use resumptionTokens, then:
We can harvest all your metadata using ListRecords. That is, ListRecords works, and resumptionTokens work properly with ListRecords, and we get the correct metadata format when we request it.
If you've implemented sets: