In the digital environment new methodologies of information management and access, coupled with advancements in digital information systems, have transformed to a great extent the ways and means of information management. Metadata, the systematic arrangement of data elements, aids the identification and location of information resources, thereby facilitating improved access to them. However, there exists unpredictability in terms of the availability, accessibility and authenticity of digital objects. Many search mechanisms retrieve a plethora of information resources, but the majority lack effectiveness and comprehensiveness.

The objectives of the present study are

• to discuss the importance of metadata harvesting service providers for the next generation library interface.

• to trace various metadata harvesting service providers.

• to study the technical details, features, metadata generation and preservation tools, server requirements, metadata elements and user support system used by those metadata harvesting service providers.

The study focuses on the current status of sixty metadata harvesting service providers. The paper is largely based on a review of the literature, both online and print. The data for this paper was downloaded from the official websites of these metadata harvesting service providers during July–August 2009.

Metadata is structured information that describes, explains, locates or otherwise makes it easier to retrieve, use or manage an information resource. Metadata is often called data about data or information about information (UKOLN website)

Interoperability in relation to metadata is search interoperability, or the ability to perform a search over diverse sets of metadata records and obtain meaningful results. Different individuals or organisations may have created metadata according to the same scheme or they may have applied of multiple schemes, as different metadata schemes serve distinct needs and audiences. Complementary schemes can be used to describe the same resource for multiple purposes and to serve a number of user groups (Baker, 2009).

There is a need to interrelate sources and types of information with different formats, data structures and description standards. Using metadata to record data about information sources allows an initial assessment of compatibility and provides an avenue for merging information or for exchanging information between systems. Interoperability is the ability of multiple systems with different hardware and software platforms, data structures and interfaces to exchange data with minimal loss of context and functionality (ALCTS/CCS Committee on Cataloging, 2000).

A metadata harvesting service harvests or indexes metadata from open access initiative (OAI) compliant archives or repositories through harvesting software that supports a protocol known as the Open Access Initiative Protocol for Metadata Harvesting (OAI-PMH). It is designed for better sharing and retrieval of e-prints residing in distributed archives, allow resources to be found by relevant criteria, identifying resources, bringing similar resources together and giving location of information (Hodge, 2003).

Harvesting refers to the activity of searching for and collecting metadata from Open Archives Initiative (OAI) Institutional Repositories (IR's) whose content is indexed and posted for open use from a World Wide Web server. An OAI harvester is software that performs the job of regularly ‘visiting’ open access databases that have informed the harvester of their existence. The harvested metadata is accrued in a database that can then be searched. The harvester's creator decides what services to provide on top of this data, for example, searching and cross-linking. The harvester can be set to harvest only metadata on a specific subject, from a select group of data providers, or from all available open access databases. The harvested metadata is archived and preserved. The Institutional Repositories commit to upgrade accessibility as technology changes. The OAI/PHM protocol is an international standard of classification fields for any item that is shared in an OAI archive such as author, content description, abstract, type of file, and other ‘tags’ that classify content in ways that can be stored and retrieved from a data base server (Coleman, 2008).

As the term denotes, a metadata harvesting protocol sets rules or guidelines for harvesting metadata.

In order to facilitate metadata harvesting, there ought to be some agreement on aspects such as: the transport protocol (HTTP or FTP etc.), the metdata format (Dublin Core, MARC, etc.); metadata quality assurance (mandatory element set, name and subject conventions, etc.) and intellectual property and usage rights.

The OAI protocol for metadata harvesting provides an application-independent interoperability framework which can be used by a variety of communities who are engaged in publishing content on the web. It provides a set of rules that defines the communication between systems such as FTP or HTTP on the internet. That is why even though the protocol actually uses HTTP as a transport mechanism between digital libraries, it is popularly known as the ‘HTTP of digital libraries’.

There are two classes of players in the OAI-PMH framework: data providers, which administer systems that support the OAI-PMH as a means of exposing metadata, and service providers, which use metadata harvested via the OAI-PMH as a basis for building value-added services.

The protocol based on HTTP and XML was developed with the objective to ensure interoperability between e-print repositories only. Later, in version 1.0/1.1, all document-like digital objects were brought within its purview, and finally the latest version 2.0 supports all kinds of digital resources.

It must be emphasised that OAI-PMH is not a search engine or a search tool or a database. It only provides a set of rules for moving the metadata (not the content) of the digital resource from one repository to another. The content remains in the source repository. A repository can act both as a service provider or harvester and data provider, or only as a service provider or data provider. The protocol is not restricted to supporting simple metadata (unqualified Dublin Core), but can support any metadata schema which can be provided in an XML format (Munshi, 2009).

A total of sixty metadata harvesting service providers were traced during the study; they were grouped as shown in Table 1.

The technical details of the metadata harvesting service providers were analysed as shown in Table 2.

From the Table 2 it can be seen that the United States is the leading country when it comes to metadata harvesting service providers: it has 22 service providers (36.66%), followed by the United Kingdom which has 16 (26.66%). Only eight providers (13.33%) were established in India. It can also be observed from Table 2 that Dublin Core is the most popular metadata standard used by metadata harvesting service providers. 25 harvesters (41.66%) use Dublin Core, 21.66% use EAD. AACR2 is used by only one service provider.

PKP is the most popular software used by 31.66% of the service providers, followed by Dspace. 15% of the service providers use CDS ware 37 service providers (61.66%) are multidisciplinary, 6 (10%) are science and technology-specific, 1 (1.66%) harvests metadata in the field of library and information science, and 4 (6.66%) in science and education.

Table 3 presents details on metdata generation: