RE: typed literals and language tags (original) (raw)

This message summarises the disadvantages of each proposal (and the fifth option of doing nothing).

Doing nothing

This leaves a language tag in the syntax of literals such as "2"@en^^xsd:int, which is (a) explicitly meaningless and (b) without rationale. This is likely to lead to user and implementor confusion and possible interoperability problems.

Option 1:

PROPOSE XML Literals are as in the working drafts prior to November 2002, in which it was not a typed literal, but a special sort of literal, with the changes made as a result of the reagle-01 and reagle-02 issues. (i,e. exc-c14n performed in the syntax document) Typed literals to exclude the language tag in the abstract syntax.

editors of Syntax, Concepts, Test and Semantics actioned to come back with text, based on current editors drafts, and last version before we switched to the rdf:XMLLiteral type, for the group approval.

This design was negatively received in earlier drafts.

With XMLLiteral as a distinct thing from typed literals then more implementors may choose not to implement it, causing interoperability problems between systems that support XML Literal, and ones that don't.

Option 2: Literals can have both a type and a language tag if and only if the type is rdf:XMLLiteral, otherwise unchanged.

PROPOSE Concepts is changed to say that a literal can only have both a datatype and a language tag when the datatype is rdf:XMLLiteral. Other editors to make consequential changes.

This excerbates rdf:XMLLiteral being an anomolous datatype, in that the syntax is anomolous as well as the semantics. This then has similar dangers (to option 1) of a schism between implementors who can be bothered with it, and those who can't.

Option 3: PROPOSE Typed literals, including XML Literal, to exclude the language tag in the abstract syntax. XML Literals to be refactored by deleting the text from concepts and putting it into syntax (probably in para 7.2.17). Add the following implementation note (or similar) to syntax. Change NTriples in test cases to show explicit for all XMLLiterals.

This is ugly in the syntax, and the hack becomes increasingly in-your-face. There is also a danger of non-backward interoperability with people who used to generate

This comes from RDF

Now getting

This comes from RDF

Option 4: Language tag is simply dropped from all typed literals including rdf:XMLLiteral

This makes it awkward to embed xhtml inside RDF maintaining language information. Since this is an important use case we probably need to:

  1. make sure that examples are included in syntax or the primer showing use of to include langauge information inside a literal.
  2. give clear warnings
  3. alert I18N

Received on Friday, 9 May 2003 06:22:20 UTC