[OAI-implementers] Searching open archives

[Pete Johnston]

Hi Howard,

As no-one seems to have replied, I'll have a go, but it may be a "Friday
afternoon" sort of answer! ;-)

> Can anyone tell me if there is a recommended means for searching an 
> OAI repository? Z3.50, SRW...? How are most repositories 
> cross-searched? Also are most repositories open to searching (by 
> users, not harvesting) or do they require authentication?

At the risk of not really answering your questions... 

The OAI-PMH spec provides the following definition of a repository:

A repository is a network accessible server that can process the 6
OAI-PMH requests in the manner described in this document. A repository
is managed by a data provider to expose metadata to harvesters [1].

i.e. an OAI-PMH repository is a service that supports harvesting using
OAI-PMH ;-)

Now, it may well be that the same set of metadata records that is made
available for harvesting is also made available through other interfaces
that support other types of interaction with the metadata records. Those
other interfaces may include

- a Web site that allows human users to browse/search the records
- a Z39.50 or SRW/U target that allows other applications to issue
searches

but OAI-PMH itself is (AFAIK!) completely neutral on whether such
interfaces are provided and/or what protocols they use - so I think it's
difficult to answer the question of whether there is "a recommended
means for searching an OAI repository"!

In practice, I suspect that, yes, some metadata databases that are
available for harvest via OAI-PMH are also available for "real-time
cross search" - via e.g. Z39.50 or SRW/U or some proprietary API. 

But some databases may be available only for harvesting - and in those
cases "cross-search" is implemented by a "service provider" harvesting
and storing metadata from multiple repositories and building a search
service on their "local" copy of that harvested metadata.

Pete

[1] http://www.openarchives.org/OAI/openarchivesprotocol.html#Repository