[MIMAS logo] MIMAS Metadatabase: Software Platform - Cheshire II

The Cheshire II Information Retrieval System

The software platform used for the MIMAS Metadatabase is Cheshire II which is a next generation online catalogue and full text information retrieval system, developed using advanced information retrieval techniques. It is open source software, free for non-commercial uses, and was developed at the University of California-Berkeley School of Information Management and Systems. Experience and requirements from the development of the MIMAS Metadatabase have been fed back into the continuing Cheshire development. As part of the project a 'sort' capability has been developed within Cheshire.

Z39.50 via Cheshire

Cheshire provides indexing and searching of XML (or SGML) data according to an XML Document Type Definition (DTD), and a Z39.50 interface. The underlying database for the MIMAS Metadatabase is a single XML data file containing all the metadata records, along with a set of indexes onto the data.

The MIMAS metadata XML is mapped to the Z39.50 Bib-1 Attribute Set for indexing and searching. Following a Z39.50 search, records may be retrieved as Simple Unstructured Text Record Syntax (SUTRS), both brief and full records, full records being similar to the above example, GRS-1 (Generic Record Syntax) and a simple tagged reference format. In addition the MIMAS Metadatabase is compliant with the Bath Profile, an international Z39.50 specification for library applications and resource discovery, providing records as simple Dublin Core in XML according to the CIMI Document Type Definition.

The mapping from the MIMAS metadata to the GRS-1 Tagset-G elements is defined in the Cheshire configuration file for the database and is used by Cheshire to return data in GRS-1 format to a requesting client. The other Z39.50 result formats are implemented by bespoke filter programs which transform the raw XML records returned by Cheshire, the 'hooks' to trigger these filters being specified in the configuration file for the database. The mapping from the MIMAS metadata to simple Dublin Core, as required by the Bath Profile, is straightforward, the base data being qualified Dublin Core, albeit with some loss of information such as subject schemes. In order to obviate this information loss as much as possible, such details are included in parentheses in the supplied record.

Details of these indicated data mappings are available.

The Cheshire Web Interface

Cheshire also provides a basic, customisable Web interface, 'webcheshire'. The web interface for the MIMAS Metadatabase is built on webcheshire as a bespoke program written in OmniMark (version 5.5). This web program provides a search interface which includes saving session information between web page accesses. It transforms retrieved records from XML to XHTML (version 1.0) for web display. OmniMark was chosen as the programming language for this interface, rather than Perl or TCL (the basic Cheshire interface language), because it is XML (or SGML) aware according to a DTD, a knowledge which is employed for the XML translations involved, and also because of existing expertise and availability on the MIMAS machine.

The MIMAS Metadatabase web interface provides search results in discrete 'chunks', currently 25 at a time, with 'next' and 'previous' navigation buttons. This is implemented by using the Cheshire capability to request a fixed number of records in the result set, beginning at a particular number within that set. The application remembers the MIMAS identifiers of the results in the retrieved 'chunk', and extracts the record corresponding to a particular MIMAS identifier when an end-user selects a 'full record display'.

To implement the metadata hierarchy navigation functionality an additional index, used internally by the application, is created on the 'isPartOf' fields of the records which denote the MIMAS identifiers of the parent records. When a record is displayed, this index is checked to find all metadata records which indicate the current record as parent, the titles of these children records also being determined from the database. For each child record found a 'hasPart' link is displayed. Similarly the title and link for the 'isPartOf' display are determined by a database look-up.

The MIMAS Metadatabase project was funded by the Joint Information Systems Committee (JISC) for the UK Higher and Further Education Councils as part of the JISC Services DNER: Z39.50/Authentication Programme.

19 July 2002, epub@manchester.ac.uk          [Go to MIMAS home page]          [Valid XHTML 1.0!]