Mapping PROV Qualified Names to xsd:QName

Mapping PROV Qualified Names to xsd:QName

1. Introduction

PROV-DM defines a PROV Identifier as a Qualified Name with the following definition: A qualified name is a name subject to namespace interpretation. It consists of a namespace, denoted by an optional prefix, and a local name. PROV-DM stipulates that a qualified name can be mapped into an IRI by concatenating the IRI associated with the prefix and the local part.

PROV-N provides a concrete syntax for prov:QUALIFIED_NAME, further noting that a PROV-N qualified name QUALIFIED_NAME can be mapped to a valid IRI [RFC3987] by concatenating the namespace denoted its local name to the local name, whose -escaped characters have been unescaped by dropping the character '' (backslash).

PROV-XML defines the type of both the prov:id and prov:ref xml-attributes to be xsd:QName as that is the XSD datatype that most closely matches the qualified name definition by PROV-DM. Care should be taken when generating PROV identifier values in PROV-XML such that there is a known mapping to a URI.

A further note adds:

The xsd:QName datatype is more restrictive than the QualifiedName defined in [PROV-N], e.g. PROV-N allows >local names to start with numbers, therefore valid identifier values in [PROV-N] serializations have to >potential to not be valid identifier values in PROV-XML. It is recommended to enhance interoperability that >provenance users strive to always use identifier schemes that map to valid xsd:QNames and URIs.

While this suggestion may work well for applications that are in full control of the design of their identifiers, this suggestion is not workable for applications, such as ProvToolbox, expected to consume arbitrary provenance in arbitrary representations. Any form of URI needs to be mapped to a Qualified Name for PROV-N and to an xsd:QName for PROV-XML.

This limitation was recognized by the Provenance Working Group, a beginning of solution was outlined in email discussions, but never made it to the PROV-XML specification.

The purpose of this document is to outline the mapping process of Qualified Names to xsd:QName adopted by ProvToolbox.

2. A Reversible Conversion

2.1 Undescore-encoding

2.2 Start espaping

3. Examples

prov:QUALIFIED_NAME(*)	xsd:QName	Comment
ex:abc	ex:abc
ex:abc01	ex:abc01
ex:01	ex:_01	QName starting by a non PN_CHAR_START to be escaped with _
ex:	ex:_	empty local name mapped to _
ex:_	ex:___	_ escaped, and escaped again since at the start
ex:a01b_c	ex:a01b__c	Escape _
ex:a@b	ex:a_40b	Mapping of @ to _40
ex:a~b	ex:a_7Eb	Mapping of ~ to _7E
ex:a&b	ex:a_26b	Mapping of & to _26
ex:a+b	ex:a_2Bb	Mapping of + to _2B
ex:a*b	ex:a_2Ab	Mapping of * to _2A
ex:a#b	ex:a_23b	Mapping of # to _23
ex:a$b	ex:a_24b	Mapping of $ to _24
ex:a!b	ex:a_21b	Mapping of ! to _21b
ex:a01bc	ex:a01bc	Mapping of to
ex:a01/bc	ex:a01_2Fbc	Mapping of / to _2F
ex:a01b\c	ex:a01b_5Cc	Mapping of \ to _5C
ex:a01b=c	ex:a01b_3Dc	Mapping of = to _3D
ex:a01b'c	ex:a01b_27c	Mapping of ' to _27
ex:a01b(c	ex:a01b_28c	Mapping of ( to _28
ex:a01b)c	ex:a01b_29c	Mapping of ) to _29
ex:a01b,c	ex:a01b_2Cc	Mapping of , to _2C
ex:a01b:c	ex:a01b_3Ac	>Mapping of : to _3A
ex:a01b;c	ex:a01b_3Bc	>Mapping of ; to _3B
ex:a01b[c	ex:a01b_5Bc	Mapping of [ to _5B
ex:a01b]c	ex:a01b_5Dc	Mapping of ] to _5D
ex:a01b.c	ex:a01b.c	. permitted in QName
ex:a01bc.	ex:a01bc.	. permitted at end of QName
ex:='(),_:;[].@~	ex:__3D_27_28_29_2C___3A _3B_5B_5D._40_7E	Escape them all except .
ex:?a\=b	ex:__3Fa_5C_3Db
ex:55348dff-4fcc-4ac2-ab56-641798c64400	ex:_55348dff-4fcc-4ac2-ab56-641798c64400	Escaping of a UUID-like QualifiedName
ex:À-ÖØ-öø-˿Ͱͽ	ex:À-ÖØ-öø-˿Ͱͽ	Support for Unicode

(*) Note that the prov:QUALIFIED_NAME column displays unescaped Qualified Names. So, the correct syntax for ex:a01bc. is ex:a01bc\. since . is not allowed in final position.

4. Provly Identifiers

5. Conclusion

We recognize that this solution is our own, and in a sense, is not inter-operable. Other solutions are possible. A future version of PROV-XML will have to specify this mapping.