[xacml] Function and data type support

[Michiharu Kudoh <KUDO@jp.ibm.com>]

For the function and data type support in XACML 1.0, I have a slight
concern about the potential overlapping with XPath 2.0 (Draft 19, April
2002). In their spec, generic operator (e.g. +, eq, gt) and its datatype
dependent function implementation (e.g. add-yearMonthDuration-to-date,
numeric-equal, numeric-greater-than) are defined in detail. What we are
trying to support is basically overlapping their work while they do not
provide any XML syntax for them. Thus my opinion is:

- XACML should incorporate the function definitions in the future once
XPath 2.0 becomes standard.
- For the XACML 1.0, minimum support for functions and data types would be
desirable for the future incorporation.
- For the functions, it's preferable to have data type neutral functions
(e.g. eq) instead of data type aware functions (e.g. numeric-equal,
datetime-equal).
- For the data types, it's preferable to avoid a duration data type because
it makes functions much complicated.

For the function declaration, my preference is Daniel's proposal
(declaration in XML document). For the function specification, my
preference is basically  the current XACML draft specification although the
current definition is lacking in semantics for the case where the argument
is list. I think the semantics of the general comparison operator defined
in XPath 2.0 is applicable to this case.

Best
Michiharu Kudo

IBM Tokyo Research Laboratory, Internet Technology
Tel. +81 (46) 215-4642   Fax +81 (46) 273-7428