Crosswalks are used to allow searches to span multiple metadata formats. For example, if one archive is harvested in the Dublin Core metadata format and another is harvested in the MARC metadata format, a Crosswalk connects the various fields in each format so that they can be searched together.
Generally, crosswalks are used to identify fields containing such information as Titles and Authors in various metadata formats.
PKP Open Harvester Systems ships with several default crosswalks; to reset the current crosswalk list to the default set, use the "Reset to Defaults" link at the bottom of the crosswalk list. This will permanently delete all existing crosswalks; use with caution.
Crosswalk Administration
When creating a new crosswalk or editing an existing crosswalk, the Administrator will be given the opportunity to select the fields it links in the various metadata formats.
A single crosswalk may link several fields in several metadata formats. For example, in the MARC schema, author information is potentially spread amongst many fields; these can be grouped into a single crosswalk.
It is not necessary for every crosswalk to support all schemas; if a crosswalk only supports a few schemas, it will only be displayed when it is relevant (based on the selected archives on the Search page).
Crosswalks may be of three types: date crosswalks, select crosswalks or text crosswalks. Note that some fields are "mixed-type", and may contain both text and date information; if so, that field will be selectable for both date crosswalks and text crosswalks.
The Schema Filter does not affect the crosswalk being modified; it merely restricts the list of fields to the selected schema. When changing the list of fields supported by a crosswalk, the administrator must save the changes with the "Save" button" before selecting another schema using the Schema Filter.
In addition to defining the search form when multiple schema are chosen, Crosswalks can be used to support record sorting for Browsing. To add this crosswalk to the list of sorting options, use the checkbox labelled "Allow users to sort records using this crosswalk when browsing records". This feature is not recommended for crosswalks that do not support all schema, or crosswalks that make use of multiple fields in a single schema.
Crosswalks may be added, deleted, and modified without requiring a re-indexing of content.