sru is a Ruby library for talking to servers that support the Search & Retrieve by URL (SRU) protocol. SRU is a lightweight API for performing information retrieval over HTTP. It is lightweight compared to its pre-HTTP ancestory Z39.50. If you are thinking about implementing SRU on the server side you should probably be looking at the much more simple and widely deployed OpenSearch.

Typically SRU clients perform a 'searchRetrieve' operation on a repository and get back different flavored XML metadata for the hits. In addition SRU clients can perform an 'explain' operation which asks the SRU server to describe itself, and its capabilities. The final operation is 'scan' which allows a client to walk an index of terms used in the target.

require 'sru'

# create the client using a base address for the SRU service
client = SRU::Client.new 'http://sru.example.com'

# fetch a SRU::ExplainResponse object from the server
explain = client.explain

# issue a search and get back a SRU::SearchRetrieveResponse object 
# which serves as an iterator 
records = client.search_retrieve 'rosetta stone', {:maximumRecords => 5}
records.each {|record| puts record}

# issue a scan request and print out each term
client.scan('king tut', {:maximumTerms => 12}).each {|term| puts term}

You should be able to install the gem:

gem install sru

More information about the project:

http://github.com/edsu/sru-ruby

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