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Cheshire3 Configuration - Protocol Map

xml

Introduction

ZeeRex is a schema for service description and is required for SRU (Search and Retrieve via URL) but it can also be used to describe Z39.50, OAI-PMH (Open Archives Initiative Protcol for Metadata Harvesting) and other information retrieval protocols.

As such, a ZeeRex description is required for each database. The full ZeeRex documentation is available at http://explain.z3950.org/ along with samples, schemas and so forth. It is also being considered as the standard service description schema in the NISO Metasearch Initiative, so knowing about it won't hurt you any.

In order to map from a CQL (Contextual Query Language) (the primary query language for Cheshire3 and SRU (Search and Retrieve via URL)) query, we need to know the correlation between CQL (Contextual Query Language) index name and Cheshire3's :py~cheshire3.baseObjects.Index object. Defaults for the SRU (Search and Retrieve via URL) handler for the database are also drawn from this file, such as the default number of records to return and the default record schema in which to return results. Mappings between requested schema and a :py~cheshire3.baseObjects.Transformer object are also possible. These mappings are all handled by a ProtocolMap.

ZeeRex Elements/Attributes of Particular Significance for Cheshire3

<database>

If you plan to make your database available over SRU (Search and Retrieve via URL), then the contents of the field MUST correspond with that which has been configured as the mount point for the SRU (Search and Retrieve via URL) web application in Apache (or an alternative Python web framework), i.e. if you configured with mapping /api/sru/ to the :py~cheshire3.web.sruApacheHandler code, then the first part of the database MUST be api/sru/.

Obviously the rest of the information in serverInfo should be correct as well, but without the database field being correct, it won't be available over SRU (Search and Retrieve via URL).

c3:index

This attribute may be present on an index element, or a supports element within <configInfo> within an <index>. It maps that particular index, or the use of the index with a <relation> or <relationModifier>, to the :py~cheshire3.baseObjects.Index object with the given id. <relationModifiers> and <relations> will override the index as appropriate.

c3:transformer

Similar to c3:index, this can be present on a <schema> element and maps that schema to the :py~cheshire3.baseObjects.Transformer used to process the internal schema into the requested one. If the schema is the one used internally, then the attribute should not be present.

Paths

zeerexPath

In the configuration for the ProtocolMap object, this contains the path to the ZeeRex file to read.

Examples

<subConfig> within the main :py~cheshire3.baseObjects.Database configuration (see index for details.):

<subConfig type="protocolMap" id="l5rProtocolMap">
    <objectType>protocolMap.CQLProtocolMap</objectType>
    <paths>
        <object type="zeerexPath">sru_zeerex.xml</path>
    </paths>
</subConfig>

Contents of the sru_zeerex.xml file:

<explain id="org.o-r-g.srw-card" authoritative="true"
    xmlns="http://explain.z3950.org/dtd/2.0/"
    xmlns:c3="http://www.cheshire3.org/schemas/explain/">
    <serverInfo protocol="srw/u" version="1.1" transport="http">
        <host>srw.cheshire3.org</host>
        <port>8080</port>
        <database numRecs="3492" lastUpdate="2002-11-26 23:30:00">srw/l5r</database>
    </serverInfo>
    [...]
    <indexInfo>
        <set identifier="http://srw.cheshire3.org/contextSets/ccg/1.0/" name="ccg"/>
        <set identifier="http://srw.cheshire3.org/contextSets/ccg/l5r/1.0/" name="ccg_l5r"/>
        <set identifier="info:srw/cql-context-set/1/dc-v1.1" name="dc"/>

        <index c3:index="l5r-idx-1">
            <title>Card Name</title>
            <map>
                <name set="dc">title</name>
            </map>
            <configInfo>
                <supports type="relation" c3:index="l5r-idx-1">exact</supports>
                <supports type="relation" c3:index="l5r-idx-15">any</supports>
                <supports type="relationModifier" c3:index="l5r-idx-15">word</supports>
                <supports type="relationModifier" c3:index="l5r-idx-1">string</supports>
                <supports type="relationModifier" c3:index="l5r-idx-16">stem</supports>
            </configInfo>
        </index>
    </indexInfo>
    <schemaInfo>
        <schema identifier="info:srw/schema/1/dc-v1.1"
            location="http://www.loc.gov/zing/srw/dc.xsd"
            sort="false" retrieve="true" name="dc"
            c3:transformer="l5rDublinCoreTxr">
            <title>Dublin Core</title>
        </schema>
    </schemaInfo>
</explain>