Comments from Steve and Ian: 1) The subset proposed is basically lifted from the IBM MRM parser help. If I ever knew what the rationale for the subset was, I don't know it now. What features have we excluded? 2) IBM MRM parser has extended the xsd regular expression syntax to allow hexadecimal characters using the following syntax: \xNN hexadecimal digits in the range 0 to F MRM makes much wider use of regular expressions, as an alternative to speculative parsing, so I can see why MRM needed this (one concrete use case was for TLOG retail messages). Do we need to support this in DFDL? 3) If we don't add the hex support, what are the use cases for using a dfdl:lengthPattern versus using an xsd pattern facet? It looks like pattern facets apply to all supported schema simple types, so not clear why dfdl:lengthPattern would be needed. The only use case I can think of is where we have length on a complex element or sequence or choice. If this is the only use case perhaps dfdl:lengthPattern should only be used in those cases? MRM allows this use. (It might also answer 2 as it allows embedded binary data to appear). Or is there a distinction between validation and parsing? 4) What is the behaviour on unparsing? I believe that MRM simply takes the value presented to it and outputs it (it does not attempt to match it against the pattern), so DFDL equivalent would be to outout the infoset value. 5) For a repeating element, presumably we would consume only as match as the number of occurs dictates. 6) Should state explicitly that DFDL entity references are not allowed. The XML character reference is used instead &#xNN; Regards, Steve Steve Hanson WebSphere Message Brokers Hursley, UK Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848 "Mike Beckerle" <mbeckerle.dfdl@gmail.com> Sent by: dfdl-wg-bounces@ogf.org 09/04/2008 01:34 Please respond to mbeckerle.dfdl@gmail.com To Alan Powell/UK/IBM@IBMGB, <dfdl-wg@ogf.org> cc Subject Re: [DFDL-WG] DFDL Regular Expression proposal Suggest add to ?lengthPattern? that the longest possible match is taken. This is the usual behavior for regular expressions, but it?s a clarification I?ve seen other places. From: dfdl-wg-bounces@ogf.org [mailto:dfdl-wg-bounces@ogf.org] On Behalf Of Alan Powell Sent: Thursday, April 03, 2008 12:44 PM To: dfdl-wg@ogf.org Subject: [DFDL-WG] DFDL Regular Expression proposal Attached is the proposal for the regular expression syntax used to determine element length. Highlights Based on the XML Schema regular expression subset used by WebSphere Message Broker. Only applies to representation = text Uses LengthPattern property rather than decorated syntax to distinguish from literals and regular expressions as it is only used in one place, this avoids everywhere else having to escape the decoration character and we are running out of decoration characters. Assumes the pattern is converted to the data code page before matching against the data stream. Comments and improvements as soon as possible please. Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU