Re: RDDL: Should xlink:arcrole or xlink:role be the primary way todispatch on related resources?

[Jonathan Borden <jborden@mediaone.net>]

Ron Daniel wrote:

>
> One thing I don't know is what you are referring to by the
> distinction between 'primary' and 'secondary'.  What is
> the difference and why is it important?

The idea is that normally only one value is specified, e.g. only
xlink:arcrole or xlink:role. The prior version of the spec specified:

<!ATTLIST rddl:resource
        xlink:role CDATA #FIXED http://www.rddl.org/#resource
..>

But as it currently stands, its only a default. The "primary" attribute is
intended to be used by most software to dispatch on a given resource. e.g.

    getResource(namespaceURI, arcrole) vs.
    getResource(namespaceURI, role)

In fact my initial Java API and implementation
(http://www/rddl.org/org/rddl) provides a Namespace interface:

import java.util.SortedMap;
import java.util.Iterator;

public interface Namespace {
 public abstract SortedMap getResourcesFromArcrole(String arcrole);
 public abstract SortedMap getResourcesFromHref(String href);
 public abstract SortedMap getResourcesFromRole(String href);
 public abstract SortedMap getResourcesFromTitle(String title);
 public abstract Resource getResourceFromId(String id);
 public abstract Iterator getResources();
 public abstract String getURI();
}

but the typical usage of a 'RDDL URL' is as follows:

    RDDLURL rurl = new RDDLURL(namespace-URI, arcrole-URI); // note: this
could just as easily be 'role-URI'
    InputStream is = rurl.getInputStream();

which dispatches on an xlink:arcrole URI (this being defined as 'primary').
The 'secondary' attribute is used to disambiguate between multiple resources
with the same 'primary' attribute.

......
>
> Is there a list of the sorts of documents you want to associate
> with the namespace URI, and the sorts of things you want to
> do with those documents?
>
http://www.rddl.org/arcrole.htm is a document we've been working on --
intended as a list of commonly used resource formats.

-Jonathan