Network Working Group P. Stickler
Internet-Draft NRC
Expires: July 17, 2002 January 16, 2002
The 'tdl:' URI Scheme for Typed Data Literals
draft-pstickler-tdl-00
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Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes the 'tdl:' Uniform Resource Identifier (URI)
scheme for Typed Data Literals
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Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. BNF for the 'tdl:' URI Scheme . . . . . . . . . . . . . . . . . 3
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 6
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1. Overview
The 'tdl:' URI scheme is intended to provide a simple but consistent
means by which a data literal (lexical form) can be paired with a
datatype URI allowing one to denote the unique data value represented
by that pairing.
The 'tdl:' URI scheme belongs to the class of URIs known as Uniform
Resource Values (URV) which are themselves a subclass of Uniform
Resource Primitives (URP), a class of URI which constitutes a
"WYSIWYG" URI, one which is not dereferencible to and does not denote
another web resource, but constitutes a self-contained resource where
the full realization of that resource is expressed in the URI itself.
For a full discussion of the properties of URPs and URVs, please see
[4]. Familiarity with the concepts defined therein will facilitate
the full understanding of this document.
Examples:
tdl:(http://www.w3.org/2001/XMLSchema#integer)15
tdl:(http://www.w3.org/2001/XMLSchema#lang)fi
tdl:(http://www.w3.org/2001/XMLSchema#NMTOKENS)foo%20bar%20bas
tdl:(http://dodo.xyz.net/x-token)foo
tdl:(voc://john.doe@widgets.org/xycoord)28.191
tdl:(uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6)392f291a093
These examples are provided for illustrative purposes only and do not
necessarily constitute actual URIs. See the BNF definition below for
an explicit definition of 'tdl:' URI syntax.
'tdl:' URIs are particularly useful for applications such as RDF [5]
where one may wish to make statements about such value resources.
E.g.
Finnish
There is the additional benefit that if canonical lexical forms are
used, every data value represented by a 'tdl:' URI in an RDF graph
will share a common graph node, which both provides a considerable
amount of graph compression compared to other literal datatyping
schemes as well as facilitates queries or inference based on typed
data values.
2. BNF for the 'tdl:' URI Scheme
This is a BNF-like description of the 'tdl:' Uniform Resource
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Identifier syntax, using the conventions of RFC 822[2], except that
"|" is used to designate alternatives, and brackets [] are used
around optional or repeated elements. Briefly, literals are quoted
with "", optional elements are enclosed in [brackets], and elements
may be preceded with * to designate n or more repetitions of the
following element; n defaults to 0.
This BNF description adopts sub-definitions defined in RFC 2396
"Uniform Resource Identifiers (URI): Generic Syntax" [1] which are
not repeated here.
tdl-URI = "tdl:" "(" type ")" value
type = absoluteURI [ "#" fragment ]
value = 1*uric
absoluteURI =
fragment =
uric =
Note that the URI scheme prefix "tdl:" is considered to be a valid
URI denoting this URI scheme, though it is not itself a valid URI
according to this URI scheme.
References
[1] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource
Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[2] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT
MESSAGES", RFC 822, August 1982.
[3] International Organization for Standardization, "ISO/IEC
11578:1996 Information technology -- Open Systems
Interconnection -- Remote Procedure Call", August 2001.
[4] Stickler, P., "An Extended Class Taxonomy of Uniform Resource
Identifier Schemes", January 2002, .
[5] Lassila, O. and R. Swick, "Resource Description Framework (RDF)
Model and Syntax Specification", February 1999, .
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Author's Address
Patrick Stickler
Nokia Research Center
Visiokatu 1
Tampere 33720
FI
EMail: patrick.stickler@nokia.com
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