[matthew]

Colocating method rules and assertions inside classes works well in mainstream OO languages. What is different here?

[matthew]

Dear Andy – ISDA have asked me to respond to you. My authority to respond is that I was responsible for the big refactoring of the rules over the past few years to the point where they’re now correct, complete, and precise. And I am the author of the XPath Specification and the XQuery Implementation of the validation rules. I am responding in my personal capacity as a longstanding participant in FpML – part of the community. My response is nothing to do with previous, current, or future employers. The specification of the validation rules was never upgraded to work with FpML 5.x. The ‘views’ mechanism introduced in 5.x subsets the schema to different business contexts. This should subset the applicable rules and the contents of the rules. This was noted as an issue by ISDA nearly 3 years ago, in Issue 611: http://www.fpml.org/issues/view.php?id=611. The last activity recorded on this issue was over a year ago. There is no published plan or timetable for addressing this issue. The issue looks readily tractable to me, and could be resolved by someone with the standing to lead the consensus in the community. Before an implementation of 5.x can be considered the specification in the Standard for 5.x must first be resolved. Any implementation of 5.x validation rules I would personally regard as speculative until the Standard is revised to handle ‘views’ for the rules. The dilemma I faced as an implementer was whether to implement the Standard as specified, including what I believed to be bugs in the Standard, or whether to implement as I believed it should have been specified. Both approaches carry risk. My usual practise was to implement rules I believed to be correct, and not to implement broken rules. Other implementations took different approaches. The very best specification of the validation rules, the “gold standard” is the XPath Description of each rule in the Standard. This specification is always precise and complete and you can evaluate the XPath inside a range of tools, for example such as MarkLogic, XML Spy and Saxon. In contrast the English Description is in places ambiguous and incomplete, and will not evaluate in any tool. The Standard contains a Comment, which is nothing more than an informative non-normative guide to intent of the rule. The XQuery implementation is part of FpML, but not part of the Standard. The XQuery implementation is straight from the XPath Description of the Standard with only some formatting added. The Validation Working Group do not maintain the XQuery implementation. I’d use the term “evaluate” rather than “execute” for a description language. The only other implementation I know of (that evaluates using the official specification), is a bank has that a XSDL 1.1 version using xs:assert statements. This is a private implementation based on the XPath descriptions; though it could be reproduced for FpML. This would be another implementation, and not part of the Standard which uses XSD 1.0. In short, the problem is readily tractable, and would take only a few man-weeks to address for all versions. The first step is to address the specification, the second step is to address the implementation of that specification. – Matthew Rawlings

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