Ok, so how can you refer to an external file from a metadata description? That is where the Resources section is for.
In the example CMDI file, the resources section looks like:
<Resources> <!-- List of external resource files and (CMDI) metadata files --> <ResourceProxyList> <ResourceProxy id="a_photo"> <ResourceType mimetype="image/jpeg">Resource</ResourceType> <!-- note that both a normal URL and a handle Persistent Identifier can be used for the ResourceRef --> <ResourceRef>hdl:1839/00-0000-0000-0009-3C7E-F</ResourceRef> </ResourceProxy> <ResourceProxy id="a_text"> <ResourceType mimetype="text/plain">Resource</ResourceType> <ResourceRef>http://www.clarin.eu/sometext.txt</ResourceRef> </ResourceProxy> ...
As you can see, for each link to an external resource a ResourceProxy (= file) is added to the ResourceProxyList (= file list). For each ResourceProxy you need to specify the ResourceType:
- Resource, the default, for a link to a web-accessible file (e.g. text file, MPEG video, file)
- Metadata in case you want to build a hierarchy of CMDI files
- SearchPage, to link to a specialised website where the described resource can be queried (more details...)
- LandingPage, to link to the "original context", e.g. the URL of a repository system displaying the digital object that is described (more details...)
- SearchService, to link to a specialised webservice where the described resource can be queried (more details...)
With an optional (but very useful) mimetype attribute you can (surprise!) indicate the file's mime type. The ResourceRef contains either a normal URL or a handle PID.