The SRU package provides a framework for working with the Search and 
Retrieval by URL (SRU) protocol developed by the Library of Congress. SRU 
defines a web service for searching databases containing metadata and 
objects. SRU often goes under the name SRW which is a SOAP version of the 
protocol. You can think of SRU as a RESTful version of SRW, since all the 
requests are simple URLs instead of XML documents being sent via some sort 
of transport layer.

WWW: http://search.cpan.org/dist/SRU/