An OAI aggregator is both a Service Provider and a Data Provider. It is a service that gathers metadata records from multiple Data Providers and then makes those records available for gathering by others using the OAI-PMH.
Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial/
The term "archive" in the name Open Archives Initiative reflects the origins of the OAI – in the E-Prints community where the term archive is generally accepted as a synonym for repository of scholarly papers. Members of the archiving profession have justifiably noted the strict definition of an “archive" within their domain; with connotations of preservation of long-term value, statutory authorization and institutional policy. The OAI uses the term “archive" in a broader sense: as a repository for stored information. Language and terms are never unambiguous and uncontroversial and the OAI respectfully requests the indulgence of the professional archiving community with this broader use of “archive."
Source: FAQ on Open Archives Initiative Web site at http://www.openarchives.org
A Data Provider maintains one or more repositories (web servers) that support the OAI-PMH as a means of exposing metadata.
Source: FAQ on Open Archives Initiative Web site at http://www.openarchives.org
In OAI-PMH, every metadata record disseminated by a repository includes a datestamp value indicating the date (and optionally time down to the second) when that record was created or last modified. Datestamps enable selective harvesting of metadata by last modified date and time.
Dublin Core (DC) is a metadata schema maintained by the Dublin Core Metadata Initiative (DCMI). The Dublin Core Metadata Element Set (DCMES) contains fifteen elements for simple resource description and discovery. Designed to be flexible and simple, DC’s elements are all optional and repeatable. DC has been extended with further optional elements, element qualifiers and vocabulary terms.
See http://www.dublincore.org/.
A DTD is a formal specification of the structure of a class of XML documents. DTDs (or XML Schemas which serve essentially the same purpose) are used to validate the correctness and completeness of XML document instances. By definition all OAI-PMH responses must be valid XML document instances.
An e-print is an author self-archived document. In the sense that the term is ordinarily used, the content of an e-print is the result of scientific or other scholarly research.
The management of the flow of data between Data Provider and Service Provider in order to assure that neither end of the transaction suffers overload. Flow control is generally realized in the OAI-PMH through the use of resumption tokens.
In the OAI context, harvesting refers specifically to the gathering together of metadata from a number of distributed repositories into a combined data store.
In OAI-PMH an identifier is a unique key for an metadata item in a repository. Each item of metadata in a repository must have a locally unique, persistent identifier. If the repository is registered with the Open Archives Website (http://www.openarchives.org/community/), and if the repository conforms to the recommended guidelines for generating OAI Identifiers, then the OAI Identifiers of that repository will be globally unique among all registered OAI providers.
Interoperability is the ability of systems, services and organizations to work together seamlessly toward common or diverse goals. In the technical arena it is supported by open standards for communication between systems and for description of resources and collections, among others. Interoperability is considered here primarily in the context of resource discovery and access.
Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial/
In OAI-PMH, item is the label for the totality of metadata contained in a repository about a single resource. Each item of metadata in a repository has a unique identifier and may be disseminated from the repository in one or more metadata formats. A metadata item disseminated in a particular metadata format is an OAI-PMH metadata record.
Structured information about resources (including both digital and non-digital resources). Metadata can be used to help support a wide range of operations on those resources. In the context of services based on metadata harvested via OAI-PMH, the most common operation is discovery and retrieval of resources.
Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial/
OAI is an initiative to develop and promote interoperability standards that aim to facilitate the efficient dissemination of content.
OAI-PMH is a lightweight harvesting protocol for sharing metadata between services.
A protocol is a set of rules defining communication between systems. FTP (File Transfer Protocol) and HTTP (Hypertext Transport Protocol) are examples of other protocols used for communication between systems across the Internet.
Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial/
In OAI-PMH a record is a metadata item disseminated in a specific metadata format. An OAI metadata record is uniquely identified by the associated item's OAI Identifier, the metadata format of the record (metadataPrefix), and the record's datestamp value.
In OAI-PMH a repository is a network accessible server that is able to process OAI-PMH requests correctly. It accepts OAI Requests and generates valid OAI Responses in reply.
In OAI-PMH a resource is an object the metadata is "about". The nature of resources is not defined in the OAI-PMH. Resources may be digital or non-digital.
When responding to certain OAI-PMH requests, data providers may optionally send an incomplete response. For instance when asked to list all records in a repository containing 1,000 items, a data provider may wish to send only 100 at a time. A ResumptionToken is included in any partial response and may be used by the harvester when requesting the next part of response.
A Service Provider issues OAI-PMH requests to data providers and uses the metadata returned as a basis for building value-added services.
Source: FAQ on Open Archives Initiative Web site at http://www.openarchives.org/
In the OAI-PMH a Set is an optional construct for grouping items in a repository. Sets allow selective harvesting of metadata.
A service that is based on harvested metadata, and adds value for its users by means which may include normalization and enriching of the harvested metadata for example. Types of services which may be offered include search services, citation linking, overlay journals, and peer-review services, among others.
Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial/
XML is a language for creating other languages. It defines a means of describing data. XML can be validated against a DTD or schema setting out the elements of the language created. XML mappings exist for a number of metadata record formats.
An XML namespace is a collection of names, identified by a URI reference [RFC2396], which are used in XML documents as element types and attribute names. XML namespaces differ from the "namespaces" conventionally used in computing disciplines in that the XML version has internal structure and is not, mathematically speaking, a set.
Source: quoted from W3C—Namespaces in XML at http://www.w3.org/TR/REC-xml-names/
XML Schemas express shared vocabularies and allow machines to carry out rules made by people. They provide a means for defining the structure, content and semantics of XML documents.
Source: quoted from W3C Architecture Domain—XML schema at http://www.w3.org/XML/Schema