DESIRE: Development of a European Service for Information on Research and Education
The demonstrator cross-searches SOSIG, ranking the results according to ratings in another ROADS database. For the purposes of this demonstrator ratings were generated automatically for the resources that result from a search for the term 'cognitive'. The generated ratings were based on the results of the WebSAT metrics tool [WEBSAT] (output as IAFA templates). In practice it is expected that human generated ratings would provide the basis for ranking.
An approach for adding flexible ranking to ROADS is described in 'Offering a Choice of Ranking Algorithms in ROADS'.
With the above technique in place it was possible to implement a number of ranking algorithms and have them selected between by the user on the search page.
Since many ranking algorithms, quality-related or otherwise, can be based on the weighting approach this functionality has been separated out and can be used by any ranking algorithm.
The ranking algorithm requires a set of attribute-value pairs and a set of attribute-weighting pairs. For each attribute in the attribute-weighting set the corresponding value is weighted and added to a running total.
The allows simple ranking based on a single attribute (such as the size of the document) as well as more complex ratings such as an accessibility rating based on a number of criteria.
The issue then becomes how to obtain the attribute-weighting pair and how to obtain the attribute-rating pairs.
WebSATAccessibility-IMGNoAltNotLink: 1 WebSATAccessibility-IMGNoAltLink: 2 WebSATAccessibility-APPLETNoAlt: 1 WebSATAccessibility-IMAGEMAPNoTextAnchor: 1
The demonstrator includes examples of each of the above. Each has a corresponding ratings algorithm that can be selected from the search page with a corresponding weighting.
It may also be appropriate if resource discovery metadata and quality ratings are harvested from other sources and can be automatically combined.
Problems occur if ratings can be provided by multiple parties. In this can values for the same attribute from different parties will need to be distinguished.
Accessing the templates from the external database can be by ROADS handle if the databases are coordinated. If not, URIs can be used if using a version of ROADS that has been extended to allow templates to be retrieved by URI.
Note that a single WHOIS++ query is generated to retrieve ratings for all resources in the result set. This offers a much faster response that the alternative of generating an individual WHOIS++ query for each result.
Note that a gateway can be placed in front of a ROADS installation to allow a ROADS database to act as a ratings bureau. This approach is used within the demonstrator.
An HTTP request is generated for every template in the result set. Obviously it would be quicker to get all ratings in a single HTTP request. This would require the ratings bureau to support such an operation. This functionality has not been implemented for client or server within this deliverable but could be added in the future.
Maintained by: Tracy Gardner of UKOLN, the UK Office for Library and Information Networking, University of Bath.
Document created: 19-Apr-1999.
Last updated: 15-Jun-1999.
[Quality Ratings] [Metadata] [UKOLN]