Differences between version 4 and predecessor to the previous major change of RDF.
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| Newer page: | version 4 | Last edited on Sunday, March 7, 2004 2:31:03 pm | by AristotlePagaltzis | Revert |
| Older page: | version 2 | Last edited on Sunday, March 7, 2004 1:32:56 am | by PerryLorier | Revert |
@@ -1,23 +1,20 @@
-[Acronym] for __R__esource __D__escription __F__ramework
+[Acronym] for __R__esource __D__escription __F__ramework.
-[RDF] is a subset of
[XML] for specifying information about some arbitary resource
. There are
[RDF] Schema's that add things you can say about
a resource (Predicates)
, and Resource types (Subjects)
. As well as constraints
, and datatypes
, and various other metadata. The common
[RDF] Schema
's are:
+[RDF] is an
[XML] language
for specifying information about some arbitary resources
. In
[RDF], everything is expressed
a series of subject-predicate-object tuples. The predicate specifies which aspect of the subject you are describing
, and the object is the subject's predicate's value
. In practice this means that the tuple "[http://www.wlug.org.nz/RDF]
, dc:title
, WLUG-Wiki RDF" expresses "the title of
[http://www.wlug.org.nz/
RDF] is
'WLUG-Wiki RDF'".
-*
[RSS
] (Rich Site Summary
): For talking about a list of items posted on a website
.
-* [FOAF]
(Friend of
a Friend): For talking about the kind of information you would put on a home page (eg, your name, your email address (hashed if you
don't want spammers to read it
)
-* DublinCore: A schema for talking about documents (who wrote it, what is it about, when was it written, a librarians wet dream)
-* Geo: For describing where an object is physically using [GPS] coordinates.
+[RDF
] Schemas specify which resource types
(subjects
) and predicates exist as well as define constraints, datatypes, and various other metadata
. (It seems to be
a fad for everyone to be creating their own schemas. Please
don't.
) The commonly encountered ones are
-As well as some "meta" schema
's for talking about RDF
-*
[OWL
] (Web Ontology Language
): For
talking about relationships between objects
-* [RDFS]
([RDF] Schema
): For specifing
[RDF
] Schemas (in RDF of course
...)
+; [RSS] 1.0 (Rich Site Summary) [1]: to describe a site
's content (very popular in the blog world)
+;
[FOAF
] (Friend of a Friend
): to describe a person (name, email, homepage, etc)
+; DublinCore: to describe A schema for
talking about documents
(who wrote it, what is it about, when was it written, a librarians wet dream
)
+; Geo
: to describe an object's location using
[GPS
] coordinates
.
-You can create your own
schemas, and
(unfortunately?
) everyone does. You can't be a good
[RDF] provider without using some obscure schema that noone has ever heard of before. Please don't
.
+There are also meta
schemas for talking about [RDF]
, like [OWL]
(the Web Ontology Language, for talking about relationships between objects
) and [RDFS] (
[RDF] Schema, for specifing [RDF] Schemas in [RDF])
.
-The core concept behind
[RDF] is that everyone is a series of 3 tuples
, (subject,predicate,object
) (eg http://www
.wlug.org.nz/RDF,dc:title,"WLUG-Wiki RDF"). The subject is what you are talking about (eg, this web page),
the Predicate is what you
are describing about the subject (eg
, it
's title), and the object is
what the value of the predicate
is for this subject (eg
, "WLUG-Wiki RDF")
.
+[RDF] is an extremely flexible language
, but unfortunately it's too young for best practises to have been established
(the [W3C] has reacted by forming a Best Practises working group
). Many of
the common schemas
are still in a state of flux
, and noone
's quite sure
what predicates to use for things or how to use various predicates. Another problem at
the moment
is that there is no obvious way to embed [RDF] data in a web page
, just to link to it as an alternate or related document
.
-Unfortunately [RDF] is in it's infancy, it's an extremely flexible language, but best practises haven't really been established yet[1]. Many of the common schema's are still in a state of flux, and noone's quite sure what predicates to use for things or how to use various predicates.
-
-(And in particular
[FOAF]) are a violation of our
privacy. However
, in at least my humble opinion, [FOAF] isn't about "
the ultimate social network" replacing [Orkut|http://www.orkut.org], it's about having
a mechanism to talk about a person.
For instance, it's common to publish a document, and
include in it
contact details about the author (
their name, their email address and perhaps home page)
. Writing
this as [RDF] means that computers can read
this information too
. You can
search documents by author,
or "post"
a reply to a document
without having to manually cut and paste the information out
. DashBoard is an example of this concept.
+People complain that [RDF]/
[FOAF] violate
privacy, but
the intent is really just to have
a mechanism to talk about a person in machine readable fashion
. For instance, it's common to include contact details about the author when publishing a document, stating
their name, their email address and perhaps home page. Providing
this information
as [RDF]/[FOAF] enables computer programs to process
this information directly
. This way you could
search documents by author or send them
a mail
without having to manually cut and paste the information. DashBoard is an example implementation
of this concept.
----
-[1]: Recently the
[W3C
] formed a Best Practises Working group to address this problem
.
+
+
[1] There are 9 incompatible schemas/DTD that claim to be "RSS", half of which aren't even remotely
[RDF
]-based
.
