Naming ModSAX features: good use for the 'java:' URI scheme?
Dan Brickley
Daniel.Brickley at bristol.ac.uk
Mon Mar 8 22:58:18 GMT 1999
On Mon, 8 Mar 1999, Tom Harding wrote:
> David Megginson wrote:
>
> > As I wrote before, it doesn't much matter whether we use Java property
> > names incorporating domain names (like
> > 'org.xml.sax.features.validation') or URIs (like
> > 'http://xml.org/sax/features/validation'), as long as we have the
> > ability for people to create new names without fear of collision.
>
> I would also urge against using an http: URI since it is not meant that a resource actually be
> retrieved using the http protocol.
I think I've found a compromise of sorts that'll let us use the Java
naming scheme (for those uncomfortable with naming conceptual entities
in the http namespace), whilst still using URIs.
>From http://www.w3.org/Addressing/schemes.html
Addressing Schemes
This is (an attempt at) an exhaustive list of URI schemes. I try to list
them all, whether they're standard or not.
Under 'J' we find a useful looking entry...
java: identifies java classes (@@spec?)
javascript:
There's also a reference to a JavaRMI: URI schema invented by Bill
Jansen, which would be interesting to track down. But anyway...
So... here's the proposal:
Naming ModSAX Features
ModSAX is intended to be easily extensible, and is designed to
anticipate future independently developed extensions ('features').
For ModSAX-aware software to cope with the decentralised evolution of
new features, it is important to have a controlled mechanism for naming
these features unambiguously. For this we adopt the Uniform Resource
Identifier (URI) system defined in RFC 2396[URI]. Each (version of a) ModSAX
feature should be assigned a unique URI. It should not be assumed that
these identifiers can always be dereferenced to acquire further
information about the feature they name.
For example, the 'http:' scheme and 'java:' schemes can be used.
'http://purl.org/net/sax/MyFeature' and 'java:org.desire.sax.MyFeature'
are both legitimate names for SAX features. 'phone:+44-117-9287493'
would not be an appropriate name, since the 'phone:' URI namespace can
only be used for telephone numbers.
This way, people who manage http: URI names and want to use them to name
SAX features are free to do so. Others can piggyback on the DNS via the
java: scheme instead. But both through the same overarching approach.
So... It would be nice to have a reference to some spec defining the 'java:'
URI scheme mentioned at http://www.w3.org/Addressing/schemes.html
Maybe somebody from Sun has a pointer to this...?
BTW as a side effect of having a URI scheme for Java classes and
intefaces, we can exchange (aggregate, search, reason over) RDF
metadata about those resources. This would be handy in Sun's JINI
amongst other places.... Here's a quick and dull example of metadata
keyed off a java: URI...
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/TR/PR-rdf-schema#"
xmlns:dc="http://purl.org/metadata/dublin_core#">
<rdf:Description rdf:about="java:org.desire.rudolf.jtree.NavApplet">
<dc:Creator>Dan Brickley and Larry Franklin</dc:Creator>
<dc:Description>This applet is an attempt at a metadata browsing tree control</dc:Description>
<rdfs:seeAlso rdf:resource="../moremetadata.rdf"/>
</rdf:Description>
</rdf:RDF>
But I'm sidetracking again. I'm really just saying one thing: the
existence of a URI schema for Java classes (and packages) means we don't
need to choose between Java and URI naming formalisms. We can have the
best of both worlds...
Dan
[URI] Uniform Resource Identifiers (URI): Generic Syntax; Berners-Lee,
Fielding, Masinter, Internet Draft Standard August, 1998; RFC2396.
http://www.isi.edu/in-notes/rfc2396.txt
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