There are times when metadata created using one standard will need to be transformed or crosswalked to another standard so that metadata can been shared between systems.
- Getting started: start walking the crosswalks for metadata
- Learn more: Hands on with crosswalking Dublin Core
- Challenge me: Hands-on with XSLT
Getting started: Why do we need crosswalks?
We learned in Thing 11 that lots of metadata schemas exist to support different data types and disciplines. There are times when metadata created in one schema will need to be transformed or crosswalked to another so that metadata can been shared between systems and is more discoverable.
1. Read the Wikipedia introduction to crosswalks.
2. Now we’ll look at an example of a metadata record that has been crosswalked to comply with different metadata standards so it can be found in various repositories. In separate windows in your browser, take a look at how the metadata for the same record has been transformed (or crosswalked) so it complies with different metadata standards and systems.
- First look at this CSIRO record in MarLIN. It was created to comply with the ISO19115 standard for describing geospatial data
- This is the same record as it appears in the CSIRO Data Access Portal
- And the same record again as it was crosswalked to the RIF-CS schema for Research Data Australia
Consider: What do you notice about these schemas? Do all three records provide exactly the same information? Or are there differences? Why can’t we have one metadata schema to rule them all, and not worry about having to crosswalk?
Thing 13: Walk the crosswalk
Learn more: Try your hand at a crosswalk
Let’s map schema!
Mapping and crosswalking metadata from one schema to another enables metadata harvesting and sharing between systems.
1. Crosswalks are viewed more easily in a table or spreadsheet format. Take a look at this example of a Dublin Core<->DDI crosswalk table.
2. Time to get hands on! Start by choosing any existing metadata record to work with. Here’s an example. This will be your “source” record. Copy the Dublin Core<->DDI crosswalk table from #1 above into Word or Excel. Can you create a high level metadata mapping from your source record to Dublin Core? (Hint: Click on “Registry View” in the bottom right-hand corner of the example source record). The Dublin Core Metadata Element Set explained in more detail. Don’t worry if you don’t have time to complete the entire record - just get a feel for the process.
Consider: the most confounding issue you encountered in make your Crosswalk. How did you overcome it?
Thing 13: Walk the crosswalk
Challenge me: An introduction to XSL for crosswalks
Hands on with XML!
This activity will provide an interactive introduction to XSLT using a free online tool.
Many well-known metadata standards are expressed as XML schemas, including MARCXML, Dublin Core, MODS, METS, EAD, RIF-CS and others. The flexible structure of XML makes it possible to convert data from one metadata standard to another using an XSLT. XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML documents.
1. Start by having a look at some of the crosswalks developed for ingesting records into Research Data Australia.
Consider: do you think experience with XML would be useful in your workplace?