Search/Retrieval via URL (SRU) is a specification for searching resources that relies on standard Web technology (HTTP, XML) for its implementation. Evergreen 1.4 supports basic SRU access through the /opac/extras/sru service defined in the Apache eg_vhost.conf configuration file and implemented in the sru_search() method in Open-ILS/src/perlmods/OpenILS/WWW/SuperCat.pm.

yaz-client is installed as a part of Index Data's YAZ software. Recent versions include support for querying SRU servers. To search Evergreen with yaz-client, choose the GET query method and issue the find command:

$ yaz-client
Z> sru GET 1.1
Z> find hemingway

If your database has records that match that term, you will get the corresponding MARCXML records in your response from yaz-client.

Here's what the SRU request looks like as sent to the Evergreen web server:

GET /opac/extras/sru?version=1.1&operation=searchRetrieve&query=hemingway&maximumRecords=0

You can see what the response looks like by hitting the same URL in your Web browser: http://dev.gapines.org/opac/extras/sru?version=1.1&operation=searchRetrieve&query=hemingway&maximumRecords=0

Evergreen supports some CQL index-sets for advanced queries such as a subset of Dublin Core (DC) elements. Those DC elements that are supported map to Evergreen default indexes as follows:

Here are a few examples of SRU searches against some of these indexes:

• dc.title all "complete dinosaur"
• dc.subject all "britain france"
• dc.title exact "The Empire Strikes Back"
• dc.author=king and dc.title=zone

Prerequisite: You must have Evergreen's SRU server running before you can enable Z39.50 server support.

This support uses an Z39.50-to-SRU translator service supplied by the Net::Z3950::Simple2ZOOM Perl module to enable Evergreen to act as a Z39.50 server. You can run the Z39.50 server on a different machine; it just needs to be able to connect to the Evergreen SRU server.

1. Install a recent version of yaz (the Makefile.install should have installed a suitable version).
2. Install Net::Z3950::Simple2ZOOM (sudo cpan Net::Z3950::Simple2ZOOM)
3. Create a Simple2ZOOM configuration file. Something like the following is a good start, and is based on the Simple2ZOOM documentation example. We'll name the file dgo.conf for our example:

   <client>
      <database name="gapines">
        <zurl>http://dev.gapines.org/opac/extras/sru</zurl>
        <option name="sru">get</option>
        <charset>utf8</charset>
        <search>
          <querytype>cql</querytype>
          <map use="4"><index>eg.title</index></map>
          <map use="7"><index>eg.keyword</index></map>
          <map use="8"><index>eg.keyword</index></map>
          <map use="21"><index>eg.subject</index></map>
          <map use="1003"><index>eg.author</index></map>
          <map use="1018"><index>eg.publisher</index></map>
          <map use="1035"><index>eg.keyword</index></map>
          <map use="1016"><index>eg.keyword</index></map>
        </search>
      </database>
   </client>

   You can have multiple <database> sections in a single file, each pointing to a different scope of your consortium. The name attribute on the <database> element is used in your Z39.50 connection string to name the database. The <zurl> element must point to http://hostname/opac/extras/sru. As of Evergreen 1.6, you can append an optional organization unit shortname for search scoping purposes, and you can also append /holdings if you want to expose the holdings for any returned records. So your zurl could be http://dev.gapines.org/opac/extras/sru/BR1/holdings to limit the search scope to BR1 and its children, and to expose its holdings.

4. Then we need to create a configuration file that will tell YAZ how to transform marcxml to binary MARC21. We will call this one xml2marc-yaz.cfg:

   <yazgfs>
       <server id="server1">
       <retrievalinfo>
           <retrieval syntax="xml"/>
           <retrieval syntax="marc21">
               <backend syntax="xml">
                   <marc inputformat="xml" outputformat="marc" outputcharset="utf-8"/>
               </backend>
           </retrieval>
       </retrievalinfo>
       </server>
   </yazgfs>

5. Run simple2ZOOM as a daemon, specifying the configuration files and one or more listener addresses that the Z39.50 server will be accessible on. If you do not specify a port, it will automatically run on port 9999. In the following example, we tell it to listen both to localhost on port 2210, and on dev.gapines.org on port 210:

   simple2zoom -c dgo.conf -- -f xml2marc-yaz.cfg localhost:2210 dev.gapines.org:210

To test the Z39.50 server, we can use yaz-client again:

yaz-client
Z> open localhost:2210/gapines
Connecting...OK.
Sent initrequest.
Connection accepted by v3 target.
ID     : 81/81
Name   : Simple2ZOOM Universal Gateway/GFS/YAZ
Version: 1.03/1.128/3.0.34
Options: search present delSet triggerResourceCtrl scan sort namedResultSets
Elapsed: 0.010718
Z> format marcxml
Z> find "dc.title=zone and dc.author=king"
Sent searchRequest.
Received SearchResponse.
Search was a success.
Number of hits: 0, setno 4
records returned: 0
Elapsed: 0.611432
Z> find "dead zone"
Sent searchRequest.
Received SearchResponse.
Search was a success.
Number of hits: 4, setno 5
records returned: 0
Elapsed: 1.555461
Z> show 1
Sent presentRequest (1+1).
Records: 1
[]Record type: XML
<record xmlns:... (rest of record deliberately truncated)