Re: [DFDL-WG] One email or a flock or... - re: 10.03 draft - open review items - update
I have added some comments in-line to reflect the WG call on Tuesday, we will continue on Friday. (Andy - please see 5 below) Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB Date: 02/10/2012 18:41 Subject: One email or a flock or... - re: 10.03 draft - open review items Steve, I've got the issues below left after your review pass on 10.03, minus 2 I send emails to you about separately. Should I issue this email to the WG, or do you want me to decompose this into separate emails, or do you just want to list these as agenda topics for next call? I think it is good if people get to look at them in advance of a call. ...mikeb -------------------------------------------------------- This is a list of items left open after a review pass by SMH(on draft in preparation r010.03). These items need specific WG discussion on a call. They may be small enough to resolve there, or may be escalated into action items. (A couple issues already clearly action-item related are not listed here.) Note: please Ignore the identifiers like SMH107 or m236 I'm tagging these with. Those are just for me editing the text. (Those change ...grrr... if someone inserts a comment into the document, so they're not good issue identifiers). 1. SMH107 Spec says: When the separator and terminator on a group have the same value, then at a point where either separator or terminator could be found, the separator is tried first. Issue is that this language still feels ambiguous. E.g., So it tries the separator first, let’s say it finds it. Will a subsequent processing error cause it to backtrack and revisit this and try the terminator? Or does finding the separator confirm that it IS a separator, resolve forever that point of uncertainty? I believe the latter is what was intended (delimiter decisions drive parsing and are not revisited), but we need to state this (or do we somewhere else already?) SMH: Would like to discuss this when Tim is present, as need to see what IBM DFDL does with separators when backtracking. 2. SMH169 - Some numeric types are signed, others unsigned. Some representations are sign-capable, some are not (BCD specifically). Right now spec draft says you can't have bcd as rep for signed integer types long, int, short, byte. But you CAN have bcd for rep of decimal, integer. We could allow bcd only for nonNegativeInteger type, but there is no nonNegativeDecimal type, so....how to resolve? I would suggest that we simply allow bcd as rep for both signed and unsigned types, and it's a processing error to unparse a negative value into bcd rep. SMH: Noted that for a decimal, property decimalSigned is used to indicate whether the logical value is signed or not. So we could disallow BCD for integer and for decimal when decimalSigned is 'yes'. Interestingly, section 3.7.1 states "Signed numbers with dfdl:binaryNumberRep 'bcd' are always positive. On unparsing it is a processing error if the data is negative." which is admitting that BCD can be used with signed types. IBM DFDL currently implements the table in the description of binaryNumberRep, and so allows BCD for integer and decimal regardless of decimalSigned, but does not allow long, short, int, byte. 3. m229 - textStandardZeroRep - should this allow %ES; as one of the list of possibles? SMH: Decided not to allow %ES; because it adds some complexity to the 'empty representation' processing rules, in the same way that xs:string and xs:hexBinary do. Can always make an element required and use default of 0. 4. m236 - is V (virtual decimal point position) and also P allowed in the textNumberPattern for double and float types? SMH: Post-call investigation: Errata 2.80 says they are allowed, but not in conjunction with E, @ and * symbols. This is reflected in BNF as subpattern := prefix? ((number exponent?) | vpinteger) suffix? 5. m237 - Do we check that the various symbols used for infinity, digits, grouping separators, decimal separators are properly distinct to allow parsing? E.g., that the decimal separator and grouping separator aren't the same, and that the positive and negative pattern variants are distinguishable? ICU library supposedly doesn't do this checking. Do we state this is an SDE in DFDL. If so then is this checking required? Can we make it possible for implementations to not check somehow? Other grammar ambiguity situations like separator and terminator being ambiguous are specifically NOT checked for, because determining if a grammar is ambiguous is hard or undecidable, and would have to be done at runtime because delimiters can be run-time computed. Buf for the syntax components of text numbers do we require checking or not? SMH: Post-call investigation: IBM DFDL gives an error if the decimal & grouping separators are the same, but does not check any of the other characters for uniqueness. (Andy - please can you check what ICU does if you set various of the text number characters to be the same value, eg, decimal sep, grouping sep, exponent and (for floats) Nan and Inf reps ?, in both strict & lax modes) 6. m370 - multiple PoU resolutions: If you have initiatedContent, AND a choiceBranchRef, AND a discriminator all on the same element, and there are 3 enclosing nested PoU, which one controls which? Precedence is the issue. Or..... do we really need to allow this? Why don’t we just disallow this kind of piling-on of complexity and make the user choose which PoU resolution technique they want? SMH: a) initiatedContent 'yes' on a choice/sequence, and a discriminator on a child of the choice/sequence. Allowed at the moment, and it is quite possible that users of IBM DFDL have this combination, so I would prefer not to make this an SDE (it's a difficult check to get right anyway due to the nature of discriminator placement). Issue a warning if a discriminator found on a direct child of the choice? b) initiatedContent 'yes' and choiceBranchRef together on a choice. Yes one is redundant, but remember that initiatedContent could have been obtained via scoping rules, so if we made the combination an SDE then we would be forcing users to explictly set initiatedContent to 'no'. I'd be ok with ignoring initiatedContent's PoU resolution behaviour if choiceBranchRef was present on a choice (note that choiceBranchRef can not be scoped). c) choiceBranchRef on choice and a discriminator on a child of the choice. Issue a warning if a discriminator found on a direct child of the choice? 7. m396 - is BCD representation a mandatory feature, or optional? SMH: BCD calendars and BCD numbers are independent optional features. Will update errata document to make this clear. 8. m398 - portability at risk if subset processors ignore properties they don't implement. We relaxed this from a more rigid policy, and now allow subsets to not validate properties they don't implement. However, is there a better compromise, e.g., require a warning about all unimplemented/unrecognized properties? E.g., dfdl:textBiDi='no' yields SDE "unrecognized property 'textBiDi' with value 'no'. SMH: Agreed that this had been relaxed too much and a warning MUST be issued by implementations. -- Mike Beckerle | OGF DFDL WG Co-Chair Tel: 781-330-0412 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
Suggest wording for issue 1 below. Change in italics: When the separator and terminator on a group have the same value, then at a point where either separator or terminator could be found, the separator is tried first. *(Speculative execution may try the terminator subsequently.)* On Wed, Oct 17, 2012 at 6:56 AM, Steve Hanson <smh@uk.ibm.com> wrote:
I have added some *comments* in-line to reflect the WG call on Tuesday, we will continue on Friday.
(Andy - please see 5 *below*)
Regards
Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/> IBM SWG, Hursley, UK* **smh@uk.ibm.com* <smh@uk.ibm.com> tel:+44-1962-815848
From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB Date: 02/10/2012 18:41 Subject: One email or a flock or... - re: 10.03 draft - open review items ------------------------------
Steve,
I've got the issues below left after your review pass on 10.03, minus 2 I send emails to you about separately.
Should I issue this email to the WG, or do you want me to decompose this into separate emails, or do you just want to list these as agenda topics for next call? I think it is good if people get to look at them in advance of a call.
...mikeb
--------------------------------------------------------
This is a list of items left open after a review pass by SMH(on draft in preparation r010.03).
These items need specific WG discussion on a call. They may be small enough to resolve there, or may be escalated into action items. (A couple issues already clearly action-item related are not listed here.)
Note: please Ignore the identifiers like SMH107 or m236 I'm tagging these with. Those are just for me editing the text. (Those change ...grrr... if someone inserts a comment into the document, so they're not good issue identifiers).
1. SMH107 Spec says: When the separator and terminator on a group have the same value, then at a point where either separator or terminator could be found, the separator is tried first.
- Issue is that this language still feels ambiguous. E.g., So it tries the separator first, let’s say it finds it. Will a subsequent processing error cause it to backtrack and revisit this and try the terminator? Or does finding the separator confirm that it IS a separator, resolve forever that point of uncertainty? I believe the latter is what was intended (delimiter decisions drive parsing and are not revisited), but we need to state this (or do we somewhere else already?)
*SMH: Would like to discuss this when Tim is present, as need to see what IBM DFDL does with separators when backtracking*.
2. SMH169 - Some numeric types are signed, others unsigned. Some representations are sign-capable, some are not (BCD specifically). Right now spec draft says you can't have bcd as rep for signed integer types long, int, short, byte. But you CAN have bcd for rep of decimal, integer. We could allow bcd only for nonNegativeInteger type, but there is no nonNegativeDecimal type, so....how to resolve? I would suggest that we simply allow bcd as rep for both signed and unsigned types, and it's a processing error to unparse a negative value into bcd rep. *SMH: Noted that for a decimal, property decimalSigned is used to indicate whether the logical value is signed or not. So we could disallow BCD for integer and for decimal when decimalSigned is 'yes'. Interestingly, section 3.7.1 states "**Signed numbers with dfdl:binaryNumberRep 'bcd' are always positive. On unparsing it is a processing error if the data is negative.**" which is admitting that BCD can be used with signed types. IBM DFDL currently implements the table in the description of binaryNumberRep, and so allows BCD for integer and decimal regardless of decimalSigned, but does not allow long, short, int, byte. *
3. m229 - textStandardZeroRep - should this allow %ES; as one of the list of possibles? * SMH: Decided not to allow %ES; because it adds some complexity to the 'empty representation' processing rules, in the same way that xs:string and xs:hexBinary do. Can always make an element required and use default of 0.*
4. m236 - is V (virtual decimal point position) and also P allowed in the textNumberPattern for double and float types? * SMH: Post-call investigation: Errata 2.80 says they are allowed, but not in conjunction with E, @ and * symbols. This is reflected in BNF as **subpattern := prefix? ((number exponent?) | vpinteger) suffix?*
5. m237 - Do we check that the various symbols used for infinity, digits, grouping separators, decimal separators are properly distinct to allow parsing? E.g., that the decimal separator and grouping separator aren't the same, and that the positive and negative pattern variants are distinguishable? ICU library supposedly doesn't do this checking. Do we state this is an SDE in DFDL. If so then is this checking required? Can we make it possible for implementations to not check somehow? Other grammar ambiguity situations like separator and terminator being ambiguous are specifically NOT checked for, because determining if a grammar is ambiguous is hard or undecidable, and would have to be done at runtime because delimiters can be run-time computed. Buf for the syntax components of text numbers do we require checking or not? * SMH: Post-call investigation: IBM DFDL gives an error if the decimal & grouping separators are the same, but does not check any of the other characters for uniqueness. **(Andy - please can you check what ICU does **if you set various of the text number characters to be the same value, eg, decimal sep, grouping sep, exponent and (for floats) Nan and Inf reps ?, in both strict & lax modes)*
6. m370 - multiple PoU resolutions: If you have initiatedContent, AND a choiceBranchRef, AND a discriminator all on the same element, and there are 3 enclosing nested PoU, which one controls which? Precedence is the issue. Or..... do we really need to allow this? Why don’t we just disallow this kind of piling-on of complexity and make the user choose which PoU resolution technique they want? *SMH: a) initiatedContent 'yes' on a choice/sequence, and a discriminator on a child of the choice/sequence. Allowed at the moment, and it is quite possible that users of IBM DFDL have this combination, so I would prefer not to make this an SDE (it's a difficult check to get right anyway due to the nature of discriminator placement). Issue a warning if a discriminator found on a direct child of the choice?* * b) initiatedContent 'yes' and choiceBranchRef together on a choice. Yes one is redundant, but remember that initiatedContent could have been obtained via scoping rules, so if we made the combination an SDE then we would be forcing users to explictly set initiatedContent to 'no'. I'd be ok with ignoring initiatedContent's PoU resolution behaviour if choiceBranchRef was present on a choice (note that choiceBranchRef can not be scoped).* * c) choiceBranchRef on choice and a discriminator on a child of the choice. Issue a warning if a discriminator found on a direct child of the choice?*
7. m396 - is BCD representation a mandatory feature, or optional? * SMH: BCD calendars and BCD numbers are independent optional features. Will update errata document to make this clear.*
8. m398 - portability at risk if subset processors ignore properties they don't implement. We relaxed this from a more rigid policy, and now allow subsets to not validate properties they don't implement. However, is there a better compromise, e.g., require a warning about all unimplemented/unrecognized properties? E.g., dfdl:textBiDi='no' yields SDE "unrecognized property 'textBiDi' with value 'no'. * SMH: Agreed that this had been relaxed too much and a warning MUST be issued by implementations. *
-- Mike Beckerle | OGF DFDL WG Co-Chair Tel: *781-330-0412* <781-330-0412>
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 https://www.ogf.org/mailman/listinfo/dfdl-wg
-- Mike Beckerle | OGF DFDL WG Co-Chair Tel: 781-330-0412
I've updated my comments based on yesterday's call and Mike's mail. Suman - please can you help with item 4 below ? Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB, Cc: dfdl-wg@ogf.org, Andrew Edwards/UK/IBM@IBMGB Date: 22/10/2012 17:29 Subject: Re: [DFDL-WG] One email or a flock or... - re: 10.03 draft - open review items - update Suggest wording for issue 1 below. Change in italics: When the separator and terminator on a group have the same value, then at a point where either separator or terminator could be found, the separator is tried first. (Speculative execution may try the terminator subsequently.) On Wed, Oct 17, 2012 at 6:56 AM, Steve Hanson <smh@uk.ibm.com> wrote: I have added some comments in-line to reflect the WG call on Tuesday, we will continue on Friday. (Andy - please see 5 below) Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB Date: 02/10/2012 18:41 Subject: One email or a flock or... - re: 10.03 draft - open review items Steve, I've got the issues below left after your review pass on 10.03, minus 2 I send emails to you about separately. Should I issue this email to the WG, or do you want me to decompose this into separate emails, or do you just want to list these as agenda topics for next call? I think it is good if people get to look at them in advance of a call. ...mikeb -------------------------------------------------------- This is a list of items left open after a review pass by SMH(on draft in preparation r010.03). These items need specific WG discussion on a call. They may be small enough to resolve there, or may be escalated into action items. (A couple issues already clearly action-item related are not listed here.) Note: please Ignore the identifiers like SMH107 or m236 I'm tagging these with. Those are just for me editing the text. (Those change ...grrr... if someone inserts a comment into the document, so they're not good issue identifiers). 1. SMH107 Spec says: When the separator and terminator on a group have the same value, then at a point where either separator or terminator could be found, the separator is tried first. Issue is that this language still feels ambiguous. E.g., So it tries the separator first, let’s say it finds it. Will a subsequent processing error cause it to backtrack and revisit this and try the terminator? Or does finding the separator confirm that it IS a separator, resolve forever that point of uncertainty? I believe the latter is what was intended (delimiter decisions drive parsing and are not revisited), but we need to state this (or do we somewhere else already?) SMH: Mike will add the following after the sentence in question " (Speculative execution may try the terminator subsequently.)". Agreed that encountering a separator does not resolve a point of uncertainty. 2. SMH169 - Some numeric types are signed, others unsigned. Some representations are sign-capable, some are not (BCD specifically). Right now spec draft says you can't have bcd as rep for signed integer types long, int, short, byte. But you CAN have bcd for rep of decimal, integer. We could allow bcd only for nonNegativeInteger type, but there is no nonNegativeDecimal type, so....how to resolve? I would suggest that we simply allow bcd as rep for both signed and unsigned types, and it's a processing error to unparse a negative value into bcd rep. SMH: Noted that for a decimal, property decimalSigned is used to indicate whether the logical value is signed or not. So we could disallow BCD for integer and for decimal when decimalSigned is 'yes'. Interestingly, section 3.7.1 states "Signed numbers with dfdl:binaryNumberRep 'bcd' are always positive. On unparsing it is a processing error if the data is negative." which is admitting that BCD can be used with signed types. IBM DFDL currently implements the table in the description of binaryNumberRep, and so allows BCD for integer and decimal regardless of decimalSigned, but does not allow long, short, int, byte. Agreed to leave rules as they are today. 3. m229 - textStandardZeroRep - should this allow %ES; as one of the list of possibles? SMH: Decided not to allow %ES; because it adds some complexity to the 'empty representation' processing rules, in the same way that xs:string and xs:hexBinary do. Can always make an element required and use default of 0. 4. m236 - is V (virtual decimal point position) and also P allowed in the textNumberPattern for double and float types? SMH: Post-call investigation: Errata 2.80 says they are allowed, but not in conjunction with E, @ and * symbols. This is reflected in BNF as subpattern := prefix? ((number exponent?) | vpinteger) suffix?. This may be too restrictive. COBOL supports 'external floating point' numbers which contain +/-, E and . characters, and so are DFDL text standard floats. See http://publib.boulder.ibm.com/infocenter/comphelp/v7v91/index.jsp?topic=%2Fc... and its child topic for some examples of these floats. Note that one example shows use of V symbol. Also experimentation with the IBM DFDL COBOL importer shows that both V & P symbols in the PIC clause are allowed. This suggest that the BNF should be revised. It be should be noted though that IBM DFDL COBOL imports these floats as xs:string and makes no attempt to convert to a number. Need to ask Suman why this is. 5. m237 - Do we check that the various symbols used for infinity, digits, grouping separators, decimal separators are properly distinct to allow parsing? E.g., that the decimal separator and grouping separator aren't the same, and that the positive and negative pattern variants are distinguishable? ICU library supposedly doesn't do this checking. Do we state this is an SDE in DFDL. If so then is this checking required? Can we make it possible for implementations to not check somehow? Other grammar ambiguity situations like separator and terminator being ambiguous are specifically NOT checked for, because determining if a grammar is ambiguous is hard or undecidable, and would have to be done at runtime because delimiters can be run-time computed. Buf for the syntax components of text numbers do we require checking or not? SMH: Post-call investigation: IBM DFDL gives an error if the decimal & grouping separators are the same, but does not check any of the other characters for uniqueness. (Andy - please can you check what ICU does if you set various of the text number characters to be the same value, eg, decimal sep, grouping sep, exponent and (for floats) Nan and Inf reps ?, in both strict & lax modes) ICU does not appear to check when setting the values for symbols if they overlap. It has precedence rules when matching (eg, match NaN before Inf, match decimal separator before grouping separator). It gives parse errors if the data does not work with its rules. To avoid having to understand these rules, it was agreed that decimal separator, group separator, exponent rep, Inf, NaN and zero rep must all be distinct, schema definition error otherwise. Noted that if decimal separator, group separator and exponent rep are expressions, this checking must be deferred until parsing/unparsing. 6. m370 - multiple PoU resolutions: If you have initiatedContent, AND a choiceBranchRef, AND a discriminator all on the same element, and there are 3 enclosing nested PoU, which one controls which? Precedence is the issue. Or..... do we really need to allow this? Why don’t we just disallow this kind of piling-on of complexity and make the user choose which PoU resolution technique they want? SMH: a) initiatedContent 'yes' on a choice/sequence, and a discriminator on a child of the choice/sequence. Allowed at the moment, and it is quite possible that users of IBM DFDL have this combination. Agreed not to make this an SDE (it's a difficult check to get right anyway due to the nature of discriminator placement), nor to issue a warning either. b) initiatedContent 'yes' and choiceBranchRef together on a choice. Yes one is redundant. Agreed to make the combination an SDE. Noted that might force users to explictly set initiatedContent to 'no' if initiatedContent 'yes' in scope. c) choiceBranchRef on choice and a discriminator on a child of the choice. Agreed not to make this an SDE (same reasoning as a) above), nor to issue a warning either. 7. m396 - is BCD representation a mandatory feature, or optional? SMH: BCD calendars and BCD numbers are independent optional features. Will update errata document to make this clear. 8. m398 - portability at risk if subset processors ignore properties they don't implement. We relaxed this from a more rigid policy, and now allow subsets to not validate properties they don't implement. However, is there a better compromise, e.g., require a warning about all unimplemented/unrecognized properties? E.g., dfdl:textBiDi='no' yields SDE "unrecognized property 'textBiDi' with value 'no'. SMH: Agreed that this had been relaxed too much and a warning MUST be issued by implementations. -- Mike Beckerle | OGF DFDL WG Co-Chair Tel: 781-330-0412 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 https://www.ogf.org/mailman/listinfo/dfdl-wg -- Mike Beckerle | OGF DFDL WG Co-Chair Tel: 781-330-0412 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
participants (2)
-
Mike Beckerle -
Steve Hanson