Transcript New PowerPoint Template

DAWG Strawman Proposal
Patrick Stickler
Forum Nokia Web Services
Nokia Technology Platforms
Patrick Stickler
© 2004 Nokia
1
DAWG Strawman Proposal
RDF Net API
+
URIQA Concise Bounded Descriptions
+
RDFQ Vocabulary
+
Result Set Vocabulary
+
Turtle
+
TriX
Patrick Stickler
© 2004 Nokia
2
DAWG Strawman Proposal
1.
RDF Net API HTTP GET & POST Bindings for retrieval requests.
2.
Some means to constrain requests to the concise bounded description of a
specific resource.
3.
Some means to constrain requests to authoritative descriptions.
4.
Input as RDF, using RDFQ as default query language.
5.
Results as RDF consisting either of Concise Bounded Descriptions or
bindings expressed with the Result Set Vocabulary.
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6.
Input queries can be efficiently expressed in Turtle.
7.
XML queries, transforms, etc. applied to graphs serialized using TriX.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
1.
RDF Net API HTTP GET & POST Bindings for retrieval requests.
Short queries can be submitted using GET, facilitating bookmarking of
frequently used queries.
Long queries can be submitted using POST, with query as message body, but
otherwise with all parameters specified in query string as per GET.
Developers are not required to implement the remainder of the RDF Net API,
nor will the WG formally recommend doing so, but developers are encouraged
to use the remainder of the RDF Net API as a starting point for further
exploration and it is anticipated that many/most implementations of the
DAWG recommendation will include full implementations of the RDF Net
API.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
2.
Some means to constrain requests to the concise bounded description of a
specific resource.
E.g. a 'uri=' parameter can be specified in the query string, with the result that
the query scope is constrained to the concise bounded description of the
specified resource.
If no other parameters are specified, the request simply equates to a request for
a concise bounded description of the specified resource.
If the request includes a query expressed in some query language, then that
query is executed only against the concise bounded description of the specified
resource rather than the entire model.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
3.
Some means to constrain requests to authoritative descriptions.
RDF Net API provides a means to access arbitrary knowledge.
We still need a way to constrain requests/results to authoritative knowledge
about a resource rather than any arbitrary knowledge present in the particular
model.
E.g. a parameter 'scope=authoritative' can constrain the request/result to
authoritative knowledge about the resource.
If the web authority of the model is not the authoritative source of knowledge
for the resource in question, the request should be considered invalid.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
4.
Input as RDF, using RDFQ as default query language.
If the request includes a query and no other 'lang=' is specified, the query is
presumed to be expressed in RDFQ.
The advantages of having query input expressed as RDF are numerous:
 Queries can be processed using RDF methods and tools, including expanding or
otherwise modifying the query based on inference rules.
 Queries can be expressed using any datatypes, providing a query formalism that is
as open and extensible as is RDF.
 Requests can include auxilliary knowledge to be included within the scope of the
query, such as resource equivalences, term relations, etc.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
5.
Results as RDF consisting either of Concise Bounded Descriptions or
bindings expressed with the Result Set Vocabulary.
Results consisting of concise bounded descriptions can be immediately
syndicated into the requesting agent's knowledge base; either as is, or after
postprocessing using RDF methods or tools.
Results consisting of variable bindings can be postprocessed using RDF
methods and tools. No special parser for binding output is required.
The output of one query request can serve as the knowledge base upon which
subsequent queries are executed, allowing for query "pipelines" to be
constructed and executed.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
6.
Input queries can be efficiently expressed in Turtle.
Probably out of scope, but can be non-normative recommendation.
Turtle, in conjunction with automatic inclusion of a default namespace and
RDFS closures, provides for a very keyboard (and hence user) friendly form of
expression which is typically as concise as Squish-based forms of expression.
[:target
[dc:creator
[a ex:Person;
ex:firstName "John";
ex:age
[:gt "30"^^xsd:integer]]]].
Patrick Stickler
[:select ("title" "description");
:target
[fn:title
[:id "title"];
fn:description
[:id "description"];
fn:published
[:gt :one-week-ago]]].
© 2004 Nokia
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DAWG Strawman Proposal
7.
XML queries, transforms, etc. applied to graphs serialized using TriX.
Probably out of scope, but can be non-normative recommendation.
The particular needs of the XML community can be addressed separately,
using a highly consistent, canonical XML serialization such as TriX.
XQuery is less optimal for RDF users as it forces one to think in terms of a
particular XML serialization rather than in terms of the RDF abstract model.
XQuery does not provide an open datatyping framework, and therefore there
can be knowledge expressed in RDF which cannot be queried using XQuery
because datatypes are employed which are not defined via XML Schema.
An XQuery based solution would require the inclusion of both an XML parser,
and an RDF parser, as well as an API facilitating interaction with both XML
structure as well as RDF graphs, substantially increasing the implementational
burden compared to an all RDF approach.
Patrick Stickler
© 2004 Nokia
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DAWG Strawman Proposal
RDF Net API
+
URIQA Concise Bounded Descriptions
+
RDFQ Vocabulary
+
Result Set Vocabulary
+
Turtle
+
TriX
Patrick Stickler
© 2004 Nokia
11