February 2010 - dfdl-wg - lists.ogf.org

8-bit-ascii for dealing with binary data in text-like manner - problematic
by Mike Beckerle 11 Feb '10

11 Feb '10

Every "8-bit-ascii" encoding I can find has holes in the code page. That is, values that don't have a corresponding character codepoint assigned. Example: iso-8859-X are a bunch of 8-bit ascii-based encodings that are popular. If you lookup iso-8859-1 it has this language: Code values 00–1F, 7F–9F are not assigned to characters by ISO/IEC 8859-1. The lower range 20 to 7E (the G0 subset) maps exactly to the same coded G0 subset of the ISO 646 US variant (commonly known as ASCII<http://en.wikipedia.org/wiki/ASCII>), ... They're saying 7-bit ascii is included, and some other codes are there, but they don't assign a codepoint generally. So, to me suggesting use of any particular code page for this purpose is somewhat ambiguous. E.g., what does &#x01 mean in a string if the encoding is iso-8859-1? There appears to be a set of translation tables that assign this to unicode in standard ways that one can find on the web. But the codepoint doesn't have an assigned meaning in iso-8859-X standards. Two possible clarifications: 1) for all ascii-based character sets, we say that bytes 0x00 to 0xFF all map to exactly those codepoints in ISO 10646 for the infoset, and vice versa. 2) define dfdl:encoding="bytes" as a special character set name which has the above property. Personally, I prefer 2. It is simpler to explain what is going on, and when people are depending on bytes it will be clearer that they are. ...mike

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fix to alignment language for draft 038
by Mike Beckerle 10 Feb '10

10 Feb '10

Fixing alignment for base 1 positions. This replaces the corresponding paragraphs in Section 14.1 of draft 038. ... An element's representation is aligned to N units if P is the first position in the representation and P mod N = 1. When parsing, the position of the first unit of the data stream is 1. For example, if alignment=4, and alignmentUnits='bytes', then the element's representation must begin at 1 or 1 plus a multiple of a 4 bytes. I.e., 1, 5, 9, 13, 17 and so on. The length of the alignment fill region is measured in bits. If alignmentUnits is ‘bytes’ then we multiply the alignment value by 8 to get the *bit alignment*, B. If the current position (first position after the end of the previous element) value is bit position N, then the length of the alignment fill region is the smallest non-negative integer L such that (L + N) mod B = 1. The position of the first bit of the aligned element is P = L + N.

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Agenda for OGF DFDL WG call 10 February 2010- 13:00 UK (8:00 ET)
by Alan Powell 09 Feb '10

09 Feb '10

1. Comments of latest discriminators doc. 2. Remaining 037 review issues 16.2 scannablility with lengthKind pattern: Confirm that this is what we agreed In summary, you can use a data pattern on any element (complex, simple text, simple binary) as long as the bytes are legal in the stated encoding, which where binary data is involved in practice means an 8-bit ASCII encoding. · Tracker Issue: [schema] is an absolute or relative SCD. Why bother allowing absolute? · Tracker Issue: Glossary as the place for centralized definitions, or should they be repeated there, but also introduced at point of first use, or should we put the definitions only at the places where they are discussed, and xref from the glossary? · TBD: Issue - semantics of expressions containing relative paths that are inherited via ref to a dfdl:defineFormat. (also section 10.3) · TBD: Issue - XPath term - we are not consistent about using the term XPath, or "expression" when referring to our expression language. I prefer to call it our expression language, and then in the section that defines it state that it is a strict subset of XPath 2.0. · TBD: Issue - fn:position is unclear given that we've just said we don't support sequences in the expression language. · TBD: Issue - order of sections. Scoping rules section should come before variables section, which uses these concepts. TBD: Issue: Case sensitivity of enum names - did we say whether this is case sensitive or not? I believe it should be case sensitive. · Issue: dfdl:representation - Strings in binary rep. I see no reason why elements of type xs:string will examine dfdl:representation. They shouldn?t' care what it is, they are always "text". I should be able to specify a bunch of inter-mixed binary number and string elements without having to specify dfdl:representation="text' just to avoid an error on the string type elements. I believe xs:string type ignores dfdl:representation (always behaves as if dfdl:representation is 'text').(If we change this then the property precedence section for simpletypes changes slightly as representation="text" is implied if type is string.) That will make it impossible to introduce a binary representation of text later What is "a binary representation of text"? Is there a real issue here. This is a primary convenience and clarity issue for me. I do not want to have to change to representation="text" for every string inside a cobol structure, which is ultimately a binary representation object. To me type="string" is enough. I want to put in the file scope level of the schema a representation="binary", and then decorate the elements with the specifics of their types, but I do not expect to have to put representation="text" on anything. I do not understand what you are trying to achieve by requiring representation="text" for things that are already textual based on the type. The rest of the issues below I think we need to discuss on calls. textStringPadCharacter textNumberPadCharacter - did we agree that this character must be a "minimum width" character if the char set encoding is variable width? (i.e., the pad char must be 1 byte if the encoding is UTF-8. numberInfinityRep numberNanRep - Is this applicable only to xs:double and xs:float? Also, what I've seen requires a distinction of sign. I.e., there are positive and negative infinities often printing as -inf and +inf. · TBD: Issue - \n in regular expressions - clarify relationship of this to entities like NL entity. Also, if I include an entity like WSP* in a regular expression (can I?) does it then match accordingly? It appears that some of our multi-valued entities like WSP+ create conditional "matching" behavior without having to use regular expressions, e.g., when WSP+ is used as a separator. But can you use entities like WSP+ in a regular expression? It seems you should be able to use regular "single valued" entities in a regular expression, its these multi-valued ones that have tricky semantics. Added Unicode values to /n, /t,/r. Disallow DFDL entities in regular expressions. 14.1 Alignment - TBD: Issue - zero-based thinking here. But all the bits stuff and everything else in DFDL uses 1-based reasoning. Need to revisit to make this sensible for 1 based world. Added implicit alignment table. TBD zero-based finalTerminatorCanBeMissing - spec is not clear. Also is there a finalSeparatorCanBeMissing Changed to finalDocumentTerminatorCanBeMissing and finalDocumentSeparatorCanBeMissing. Not sure where finalDocumentSeparatorCanBeMissing should be specified. Looks odd on 'distinguished root'. These properties operate differently from other properties as they are defined on the 'distinguished root' but affect some lower down element. Effectively they are put in scope by a different mechanism 3. Go through Actions Current Actions: No Action 045 20/05 AP: Speculative Parsing 27/05: Psuedo code has been circulated. Review for next call 03/06: Comments received and will be incorporated 09/06: Progress but not discussed 17/06: Discussed briefly 24/06: No Progress 01/07: No Progress 15/07: No progress. MB not happy with the way the algorithm is documented, need to find a better way. 29/07: No Progress 05/08: No Progress. Will document behaviour as a set of rules. 12/08: No Progress ... 16/09: no progress 30/09: AP distributed proposal and others commented. Brief discussion AP to incorporate update and reissue 07/10: Updated proposal was discussed.Comments will be incorporated into the next version. 14/10: Alan to update proposal to include array scenario where minOccurs > 0 21/10: Updated proposal reviewed 28/10: Updated proposal reviewed see minutes 04/11: Discussed semantics of disciminators on arrays. MB to produce examples 11/11: Absorbing action 033 into 045. Maybe decorated discrminator kinds are needed after all. MB and SF to continue with examples. 18/11: Went through WTX implementation of example. SF to gather more documentation about WTX discriminator rules. 25/11: Further discussion. Will get more WTX documentation. Need to confirm that no changes need to Resolving Uncertainty doc. 04/11: Further discussion about arrays. 09/12: Reviewed proposed discriminator semantic. 16/12: Reviewed discriminator examples and WTX semantic. 23/12: SF to provide better description of WTX behaviour and invite B Connolley to next call 06/01:B Connolly not available. SF to provide more complete description. 13/01: Stephaine took us through a description of WTX identifiers. Mike agreed to write up in DFDL terms. 20/01: Mike will write up 27/01: further discussion of discriminators 29/01: Alan had emailed both proposals but not enough time to discuss 02/02: Agreed to adopt 'component exists' semantics for discriminators 049 20/05 AP Built-in specification description and schemas 03/06: not discussed 24/06: No Progress 24/06: No Progress (hope to get these from test cases) 15/07: No progress. Once available, the examples in the spec should use the dfdl:defineFormat annotations they provide. ... 14/10: no progress 21/10: Discussed the real need for this being in the specification. It seemed that the main value is it define a schema location for downloading 'known' defaults from the web. 28/10: no progress 04/11: no progress 11/11: no update 18/11: no update 25/11: Agreed to try to produce for CSV and fixed formats 04/12: no update 09/12: no update 16/12: no update 23/12: no update 06/01: no progress. If there is no resource to complete this action it can be deferred 13/01:no progress 20/01: no progress 27/01: no progress 29/01: No progress. The predefined formats do not need to be available when the spec is published. Suman said that he had been mapping COBOL structures to DFDL and it didn't look as though the way text numbers are define is very usable. He will document for next call 03/03: No progress 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update 09/12: no update 16/12: reminded dent to project manager 23/12: SH will send another reminder. 06/01: Another reminder will be sent 13/01: no update 20/01: no update 27/01: no progress 29/01: no progress 03/02: IBM is still invetsigating 077 SKK: mapping of COBOL numbers to textNumberFormats. 03/02: Suman documented the problem. Agreed to remove textNumberFormat and textCalendarFormat. 078 MB: Reword section 2.3.1 incorporating markup order rules. Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)uk.ibm.com 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

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DFDL Discriminators
by Alan Powell 09 Feb '10

09 Feb '10

I have updated the proposal based on the WG call last week. I have also merged in the full description of discriminators. This will be section 7.4 in the dfdl annotations section so will not follow the Uncertainty section. I have also corrected the syntax of the examples. Not all the examples will end up in the spec Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)uk.ibm.com 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

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new language for 2.3.1 of draft 038
by Mike Beckerle 07 Feb '10

07 Feb '10

Below is new language for section 2.3.1. I decided that the issue here is about ambiguity in general, and not just lengthKind="delimited". I also can't think of any other situation like this one besides ambiguity. Are there others? ...mikeb 2.3.1 Ambiguity of Data Formats A data format description using dfdl:lengthKind="delimited" may be ambiguous if the delimiters are not distinct, and a data format description which has fixed data requirements (some elements having required fixed values), may be ambiguous regardless of the dfdl:lengthKind setting.[1] <#_ftn1> Note that if the delimiter string values are stored within the data, perhaps as elements of a header part of the data, then this ambiguity certainly cannot be examined until the data is available. Given an ambiguous grammar, a DFDL implementation may successfully parse a particular input data stream. That is, the part of the schema with the ambiguity may not be exercised by a particular data stream, or the data may parse successfully anyway; that is, the ambiguity may not cause any kind of failure or processing error. Hence, to insure compatible behavior, DFDL v1.0 implementations MUST not detect grammar ambiguities as errors. Implementations are of course free to issue warnings to help users identify these situations, but ambiguity is neither a Schema Definition Error, nor a Processing Error. ------------------------------ [1] <#_ftnref1> A very complex analysis is required to identify this sort of grammar ambiguity in general. While we believe this may be decidable for DFDL v1.0, future versions of DFDL may add features (such as recursive types) which make this analysis undecidable.

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Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup
by Tim Kimber 04 Feb '10

04 Feb '10

Good question - I must admit that I put that in as an afterthought. There's an attempted explanation below, which might be off target. Consider this sequence: <xs:sequence dfdl:sequenceKind="ordered" dfdl:initiatedContent="true" dfdl:separator=":" dfdl:separatorPosition="infix" dfdl:separatorPolicy="require" > <xs:element dfdl:initiator=":a:" lengthKind="delimited" minOccurs="0"/> <xs:element dfdl:initiator=":b:" lengthKind="delimited" minOccurs="0"/> </xs:sequence> It could have the following representations: {:a:valueOfA::b:valueOfB} {::b:valueOfB} {,} After parsing the { the next item could be either a's initiator, or the group's separator. I'm saying that a's intiator takes precedence here. ( in other words, when parsing a group's content we look for the initiator of the first element before scanning for terminating markup ) Alternatively, we could specify the opposite behaviour and insist that in-scope terminating markup is always checked before any other group content. That would make the above difficult or impossible to parse using DFDL, I think. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert(a)uk.ibm.com Tel. 01962-816742 Internal tel. 246742 From: Steve Hanson/UK/IBM To: Tim Kimber/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org Date: 04/02/2010 15:53 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Tim - can you clarify the last sentence please - is the terminating markup that of the preceding peer element, or the enclosing parent? Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh(a)uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg(a)ogf.org Date: 03/02/2010 17:47 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Sent by: dfdl-wg-bounces(a)ogf.org These rules seem to work: a) separators and terminators are collectively called 'terminating markup'. b) initiators are not 'terminating markup' c) when two items of in-scope terminating markup have a common prefix, the parser must give precedence to the longest item. d) when two items of in-scope terminating markup have exactly the same value, the parser must give precedence to the innermost ( most deeply nested ) item. e) when the separator and terminator on a group have exactly the same value, the parser must give precedence to the separator. If an initiated component can occur at the same point as an item of terminating markup, the initiator takes precedence. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert(a)uk.ibm.com Tel. 01962-816742 Internal tel. 246742 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(a)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

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Minutes for OGF DFDL Working Group Call, February 02 & 03-2010
by Alan Powell 04 Feb '10

04 Feb '10

Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, February 02 & 03-2010 Attendees Mike Beckerle (Oco) Steve Hanson (IBM) Alan Powell (IBM) Suman Kalia (IBM) Peter Lambros (IBM) Tim Kimber(IBM) Apologies Stephanie Fetzer (IBM) Steve Marting (Progeny) 1. Discriminators Discussed the 'parent exists' and 'component exists' options for dfdl:discriminator semantics. The WG agreed that DFDL would adopt the 'component exists' semantics where the discriminator indicates that the component it is on exists and does not say anything about the components parent. Examples need minor changes and full syntax. Arrays would be the same as optional components. Discriminators are not allowed on - Global groups and the top level sequence or choice of a global group. - Global element decalrations - The top level group of a complex type. - Anonymous groups other than when it is the top level of a choice branch. The discriminator timing property was also discussed. It was agreed that a parser should be able to tell when it is possible to evaluate the expression so the timing property will be removed. The following will be added instead 'The expression will be evaluated when the referenced elements are known to exist or known not to exist.' Timing on asserts was also mention but deferred for the time being. Alan will update the 'component exists' proposal. 1. Action 077 Cobol and numberFormats Suman highlighted a problem using textNumberFormat for COBOL numbers where a separate textNumberFormat is required for each length. This is because a different numberPattern is required for each one. It was suggested that numberPattern was move from textNumberFormat to the standard properties but it was decided to get rid of textNumberFormat altogether and move all the properties. Tim pointed out that this meant that is was now not possible to just vary the number properties so there may be more definedFormats but this was not felt to be a problem. For consistency it was agreed that textCalendarFormat would also be removed. EscapeScheme is different so will be retained. 2. Remaining 037 review issues 2. I agree with the existing comment that the RFC2119 key words should be upper case. Agreed that the RFC2119 keywords should be in upper case and wherever possible the spec should be reworded to use the key words. 16.2 scannablility with lengthKind pattern: One use case it to find the end of of a character element by looking for 'binary' bytes of the following element. Discussed whether dfdl:lengthKind pattern should be allowed for binary elements. Pattern scanning inherently treats the data as characters but for single byte encodings a binary byte can be specified by its character codepoint. Agreed that dfdk:lengthKind pattern will be allowed for binary elements when the encoding is US-ASCII. (why didn't we say any single byte character set?) Section 16.2 says that that the children on a complex type must not change the encoding. This will be relaxed when encoding is US-ASCII. DFDL raw entities will not be allowed in a pattern. Tracker Issue: illegal character encodings for parsing and unparsing. What should DFDL do when it finds illegal bytes when converting strings during parsing and unparsing? Discussed adding a new property to declare a substitution character. Discussed what products do and ICU. Decided to follow ICU. Conversions to Unicode (during parsing) will substitue characters that cannot be converted with the unicode substitute character (U+FFFD). When converting from Unicode (during unparsing) they will be substituted with the substitute character for that encoding, for example 0x1A (Control-Z) for ASCII. Tracker Issue: Processing-time Schema Definition Errors Mike will reword Section 2.3.1 Tim will supply rules for the order that terminators and separators are look for in the data stream Tracker Issue: "round trip" for infoset. Should we omit the whole point? Rephrase sentence 'It is possible to define a schema so that when infoset unparsed and the datastream reparsed, the same infoset will be produced' 3. Go through Actions Meeting closed, 15:00 Next call Tuesday 10 February January 2010 13:00 UK Next action: 079 Actions raised at this meeting No Action 078 MB: Reword section 2.3.1 incorporating markup order rules. Current Actions: No Action 045 20/05 AP: Speculative Parsing 27/05: Psuedo code has been circulated. Review for next call 03/06: Comments received and will be incorporated 09/06: Progress but not discussed 17/06: Discussed briefly 24/06: No Progress 01/07: No Progress 15/07: No progress. MB not happy with the way the algorithm is documented, need to find a better way. 29/07: No Progress 05/08: No Progress. Will document behaviour as a set of rules. 12/08: No Progress ... 16/09: no progress 30/09: AP distributed proposal and others commented. Brief discussion AP to incorporate update and reissue 07/10: Updated proposal was discussed.Comments will be incorporated into the next version. 14/10: Alan to update proposal to include array scenario where minOccurs > 0 21/10: Updated proposal reviewed 28/10: Updated proposal reviewed see minutes 04/11: Discussed semantics of disciminators on arrays. MB to produce examples 11/11: Absorbing action 033 into 045. Maybe decorated discrminator kinds are needed after all. MB and SF to continue with examples. 18/11: Went through WTX implementation of example. SF to gather more documentation about WTX discriminator rules. 25/11: Further discussion. Will get more WTX documentation. Need to confirm that no changes need to Resolving Uncertainty doc. 04/11: Further discussion about arrays. 09/12: Reviewed proposed discriminator semantic. 16/12: Reviewed discriminator examples and WTX semantic. 23/12: SF to provide better description of WTX behaviour and invite B Connolley to next call 06/01:B Connolly not available. SF to provide more complete description. 13/01: Stephaine took us through a description of WTX identifiers. Mike agreed to write up in DFDL terms. 20/01: Mike will write up 27/01: further discussion of discriminators 29/01: Alan had emailed both proposals but not enough time to discuss 02/02: Agreed to adopt 'component exists' semantics for discriminators 049 20/05 AP Built-in specification description and schemas 03/06: not discussed 24/06: No Progress 24/06: No Progress (hope to get these from test cases) 15/07: No progress. Once available, the examples in the spec should use the dfdl:defineFormat annotations they provide. ... 14/10: no progress 21/10: Discussed the real need for this being in the specification. It seemed that the main value is it define a schema location for downloading 'known' defaults from the web. 28/10: no progress 04/11: no progress 11/11: no update 18/11: no update 25/11: Agreed to try to produce for CSV and fixed formats 04/12: no update 09/12: no update 16/12: no update 23/12: no update 06/01: no progress. If there is no resource to complete this action it can be deferred 13/01:no progress 20/01: no progress 27/01: no progress 29/01: No progress. The predefined formats do not need to be available when the spec is published. Suman said that he had been mapping COBOL structures to DFDL and it didn't look as though the way text numbers are define is very usable. He will document for next call 03/03: No progress 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update 09/12: no update 16/12: reminded dent to project manager 23/12: SH will send another reminder. 06/01: Another reminder will be sent 13/01: no update 20/01: no update 27/01: no progress 29/01: no progress 03/02: IBM is still invetsigating 077 SKK: mapping of COBOL numbers to textNumberFormats. 03/02: Suman documented the problem. Agreed to remove textNumberFormat and textCalendarFormat. 078 MB: Reword section 2.3.1 incorporating markup order rules. Closed actions No Action Work items: No Item target version status 005 Improvements on property descriptions not started 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 036 Update dfdl schema with change properties ongoing 042 Mapping of the DFDL infoset to XDM none not required for V1 specification 069 ICU fractional seconds 039 070 Write DFDL primer 071 Write test cases. 072 it is a processing error if the number of occurrences in the data does not match the value of the expression or prefix 039 073 Rename dfdl:separatorPolicy="required" to "always". 039 Defferred untilaction 071 agreed 078 document UPA checks 039 079 Semantics of length=0, nil handling and defaults. (A071) 039 080 Tlog: Allow LengthKind delimited for packed/bcd (A074) 039 081 Update empty sequence section (A075) 039 082 semantics of minOccurs= 0 on choice branches (A076) 039 083 Implement RFC2116 084 Length|Kind pattern scanability rules 085 Invalid character substitution Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)uk.ibm.com 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

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Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup
by Tim Kimber 04 Feb '10

04 Feb '10

These rules seem to work: a) separators and terminators are collectively called 'terminating markup'. b) initiators are not 'terminating markup' c) when two items of in-scope terminating markup have a common prefix, the parser must give precedence to the longest item. d) when two items of in-scope terminating markup have exactly the same value, the parser must give precedence to the innermost ( most deeply nested ) item. e) when the separator and terminator on a group have exactly the same value, the parser must give precedence to the separator. If an initiated component can occur at the same point as an item of terminating markup, the initiator takes precedence. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert(a)uk.ibm.com Tel. 01962-816742 Internal tel. 246742 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

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Fw: Agenda for OGF DFDL WG call 03 February 2010- 13:00 UK (8:00 ET)
by Alan Powell 03 Feb '10

03 Feb '10

1. Action 077 Cobol and numberFormats Review two options (attached) 2. Remaining 037 review issues See below 3. Go through Actions Current Actions: No Action 045 20/05 AP: Speculative Parsing 27/05: Psuedo code has been circulated. Review for next call 03/06: Comments received and will be incorporated 09/06: Progress but not discussed 17/06: Discussed briefly 24/06: No Progress 01/07: No Progress 15/07: No progress. MB not happy with the way the algorithm is documented, need to find a better way. 29/07: No Progress 05/08: No Progress. Will document behaviour as a set of rules. 12/08: No Progress ... 16/09: no progress 30/09: AP distributed proposal and others commented. Brief discussion AP to incorporate update and reissue 07/10: Updated proposal was discussed.Comments will be incorporated into the next version. 14/10: Alan to update proposal to include array scenario where minOccurs > 0 21/10: Updated proposal reviewed 28/10: Updated proposal reviewed see minutes 04/11: Discussed semantics of disciminators on arrays. MB to produce examples 11/11: Absorbing action 033 into 045. Maybe decorated discrminator kinds are needed after all. MB and SF to continue with examples. 18/11: Went through WTX implementation of example. SF to gather more documentation about WTX discriminator rules. 25/11: Further discussion. Will get more WTX documentation. Need to confirm that no changes need to Resolving Uncertainty doc. 04/11: Further discussion about arrays. 09/12: Reviewed proposed discriminator semantic. 16/12: Reviewed discriminator examples and WTX semantic. 23/12: SF to provide better description of WTX behaviour and invite B Connolley to next call 06/01:B Connolly not available. SF to provide more complete description. 13/01: Stephaine took us through a description of WTX identifiers. Mike agreed to write up in DFDL terms. 20/01: Mike will write up 27/01: further discussion of discriminators 29/01: Alan had emailed bot proposals but not enough time to discuss 049 20/05 AP Built-in specification description and schemas 03/06: not discussed 24/06: No Progress 24/06: No Progress (hope to get these from test cases) 15/07: No progress. Once available, the examples in the spec should use the dfdl:defineFormat annotations they provide. ... 14/10: no progress 21/10: Discussed the real need for this being in the specification. It seemed that the main value is it define a schema location for downloading 'known' defaults from the web. 28/10: no progress 04/11: no progress 11/11: no update 18/11: no update 25/11: Agreed to try to produce for CSV and fixed formats 04/12: no update 09/12: no update 16/12: no update 23/12: no update 06/01: no progress. If there is no resource to complete this action it can be deferred 13/01:no progress 20/01: no progress 27/01: no progress 29/01: No progress. The predefined formats do not need to be available when the spec is published. Suman said that he had been mapping COBOL structures to DFDL and it didn't look as though the way text numbers are define is very usable. He will document for next call 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update 09/12: no update 16/12: reminded dent to project manager 23/12: SH will send another reminder. 06/01: Another reminder will be sent 13/01: no update 20/01: no update 27/01: no progress 29/01: no progress 077 SKK: mapping of COBOL numbers to textNumberFormats. A few comments in-line below On Wed, Jan 20, 2010 at 7:01 AM, Alan Powell <alan_powell(a)uk.ibm.com> wrote: I have answered most of the issues and comments raised by Steve and Mike but some need further discussion. Issues from Steve H 2. I agree with the existing comment that the RFC2119 key words should be upper case. 16.2. I'm not sure that scannability in this constant encoding sense is necessary for patterns. I can create a regular expression that extracts all characters up to hex value xXX or all characters up to xYY, thereby treating the content as an encoding in-sensitive black box. If your byte pattern happens to be a legal part of a multi-byte character sequence, then you'll get a false recognition, or you won't get what you expect. Example: You are searching for byte 0xAA, but that can legally appear as byte 3 of a 3-byte UTF-8 encoded character. When you say you are looking for hex AA in a string, DFDL is currently defined to mean you are looking for the character reprsented by that raw byte. If the encoding is UTF-8, that isn't a legal character encoding sequence even, so the decoder should cause an error or something. Even for a fixed length single byte character set, you have to have no unused code that have no mapping to ISO 10646, because our infoset is defined in terms of translations into that. I think we need encoding="none" or encoding="bytes" or something if you really want to scan bytes without encoding causing problems. Issues from Mike B · Tracker issue: codepoints outside BMP, as literals and in data. · If I put in a value that requires use of a high/low surrogate pair, is that an error, does it require me to put in two separate %#...; thingys, one for each of the surrogates (in which case these are not really code points in ISO10646). If I put in a codepoint for one of the supplemental characters and the schema itself is written in UTF-16 then that has to translate into literal surrogate pair. Ok, but I?m very uncertain about all this stuff The above item had two issues glomed together. There really are two separate issues. The above is about these crazy codepoints that use surrogate pairs. That's a minor corner case given the amount of use those get. The bigger issue is the one below, which is about things that either are in strings and are broken character encodings, but we still need to be able to process the data. There's also the matter of recovery from errors in decoding, and what we put out when the infoset contains a character code where there is no valid encoding, or just a character code which isn't even in ISO 10646 (e.g., character code 0xFFFFFFFF, which is not a valid character at all. Tracker Issue: illegal character encodings for parsing and unparsing. TBD: how do these make it into the infoset or are they replaced, and if so how TBD: can one represent these in the infoset for output? Ideally not, but? · Tracker Issue: Processing-time Schema Definition Errors This section (2.3.1 in this draft), is problematic as we?re trying to allow simple DFDL implementations to not do a bunch of static checking, yet if implementations differ on when Schema Definition errors are detected, then the second paragraph says they are converted to processing errors. This lets different implementations do very different things in terms of how the speculative parsing back-tracks around. Grammar ambiguity is a very tricky case. Unless a DFDL implementation can prove a grammar to be unambiguous, then it is very hard to say that any particular combinatino of delimiters make up a legal DFDL schema definition. If the parser simply fails because the grammar was ambiguous, there?s no way to tell the difference between this and just broken data without proving the grammar is unambiguous. In general it is formally undecidable whether a grammar is ambiguous or unambiguous. ( http://books.google.com/books?id=lIuu53IcKWoC&pg=PT217&lpg=PT217&dq=proving… ) Since DFDL v1.0 doesn?t allow recursive declarations/definitions, it may be possible to provide the ambiguity or unambiguity of a DFDL schema (or rather, the data syntax grammar described by it ? if you want to bother to distinguish the two), but recursion isn?t something we want to rule out for the future, so Type checking is decidable in DFDL?s expression language, so we could always detect type safety before run time; however, if we allow a simplistic DFDL implementation to just check types at run time then this would, by the definition in this section (2.3.1), issue processing errors when it detects these at run time, thereby allowing backtracking of the speculative parser to be driven off of type-checks in the expression language. It seems to me that we need to find a way to put this problem back into the hands of the user, and say that a schema where this actually matters (one where a type error causes a backtrack, which ultimately causes a successful parse) are illegal but implementations are allowed to not detect this particular illegality. It seems to me we need to put this problem back into the hands of the user. · Tracker Issue: "round trip" for infoset. Should we omit the whole point? · Tracker Issue: [schema] is an absolute or relative SCD. Why bother allowing absolute? · Tracker Issue: Glossary as the place for centralized definitions, or should they be repeated there, but also introduced at point of first use, or should we put the definitions only at the places where they are discussed, and xref from the glossary? · TBD: Issue - semantics of expressions containing relative paths that are inherited via ref to a dfdl:defineFormat. (also section 10.3) · TBD: Issue - XPath term - we are not consistent about using the term XPath, or "expression" when referring to our expression language. I prefer to call it our expression language, and then in the section that defines it state that it is a strict subset of XPath 2.0. · TBD: Issue - fn:position is unclear given that we've just said we don't support sequences in the expression language. · TBD: Issue - order of sections. Scoping rules section should come before variables section, which uses these concepts. TBD: Issue: Case sensitivity of enum names - did we say whether this is case sensitive or not? I believe it should be case sensitive. · Issue: dfdl:representation - Strings in binary rep. I see no reason why elements of type xs:string will examine dfdl:representation. They shouldn?t' care what it is, they are always "text". I should be able to specify a bunch of inter-mixed binary number and string elements without having to specify dfdl:representation="text' just to avoid an error on the string type elements. I believe xs:string type ignores dfdl:representation (always behaves as if dfdl:representation is 'text').(If we change this then the property precedence section for simpletypes changes slightly as representation="text" is implied if type is string.) That will make it impossible to introduce a binary representation of text later What is "a binary representation of text"? Is there a real issue here. This is a primary convenience and clarity issue for me. I do not want to have to change to representation="text" for every string inside a cobol structure, which is ultimately a binary representation object. To me type="string" is enough. I want to put in the file scope level of the schema a representation="binary", and then decorate the elements with the specifics of their types, but I do not expect to have to put representation="text" on anything. I do not understand what you are trying to achieve by requiring representation="text" for things that are already textual based on the type. The rest of the issues below I think we need to discuss on calls. textStringPadCharacter textNumberPadCharacter - did we agree that this character must be a "minimum width" character if the char set encoding is variable width? (i.e., the pad char must be 1 byte if the encoding is UTF-8. numberInfinityRep numberNanRep - Is this applicable only to xs:double and xs:float? Also, what I've seen requires a distinction of sign. I.e., there are positive and negative infinities often printing as -inf and +inf. · TBD: Issue - \n in regular expressions - clarify relationship of this to entities like NL entity. Also, if I include an entity like WSP* in a regular expression (can I?) does it then match accordingly? It appears that some of our multi-valued entities like WSP+ create conditional "matching" behavior without having to use regular expressions, e.g., when WSP+ is used as a separator. But can you use entities like WSP+ in a regular expression? It seems you should be able to use regular "single valued" entities in a regular expression, its these multi-valued ones that have tricky semantics. Added Unicode values to /n, /t,/r. Disallow DFDL entities in regular expressions. 14.1 Alignment - TBD: Issue - zero-based thinking here. But all the bits stuff and everything else in DFDL uses 1-based reasoning. Need to revisit to make this sensible for 1 based world. Added implicit alignment table. TBD zero-based finalTerminatorCanBeMissing - spec is not clear. Also is there a finalSeparatorCanBeMissing Chaned to finalDocumentTerminatorCanBeMissing and finalDocumentSeparatorCanBeMissing. Not sure where finalDocumentSeparatorCanBeMissing should be specified. Looks odd on 'distinguished root'. These properties operate differently from other properties as they are defined on the 'distinguished root' but affect some lower down element. Effectively they are put in scope by a different mechanism Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)uk.ibm.com 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 [attachment "Resolving Uncertainty and Discriminators- parent exists- v3.doc" deleted by Alan Powell/UK/IBM] [attachment "Resolving Uncertainty and Discriminators- component exists- v3.doc" deleted by Alan Powell/UK/IBM] -- dfdl-wg mailing list dfdl-wg(a)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

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Re: [DFDL-WG] Action Item 049: Built-in specification description and schemas
by Suman Kalia 02 Feb '10

02 Feb '10

Thanks Steve for your note.. Comments below I agree there will be handful of escape schemes and the opportunity for their reuse is very high.. Looking at Calendar format - the attribute that would vary most are calendarPattern followed by calendarTimeZone. calendarPatternKind goes along with calendarPattern; it tells whether to use calendar pattern from schema date/time type or from DFDL properties. Rest of the attributes are likely to be same for a particular format. For consistency with textNumberFormat, I am fine to add all attributes defined in calendarFormat to dfdl:element and dfdl:simpleType.. Suman Kalia IBM Toronto Lab WMB Toolkit Architect and Development Lead WebSphere Business Integration Application Connectivity Tools http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.h… Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia(a)ca.ibm.com From: Steve Hanson/UK/IBM@IBMGB To: Suman Kalia/Toronto/IBM@IBMCA Cc: dfdl-wg(a)ogf.org Date: 02/02/2010 04:59 AM Subject: Re: Action Item 049: Built-in specification description and schemas Thanks for highlighting this Suman. The reason for hiving off the properties for text numbers into a separate named annotation was reuse. It was considered that a given data format might have a large number of text number fields, but that they could be described by a far lesser number of annotations, because a limited set of 'number patterns' were used. In Suman's example that's clearly not the case, but it is an artificial one. We need to consider real world formats. I've had a look through example COBOL copybooks, and while there is a large variation in text number fields, reuse of 'number patterns' would be a benefit. For example, a set of related values might be declared the same: 15 ORIGINAL-PRICE PIC 9(013)V99. 15 DISCOUNTED-PRICE PIC 9(013)V99. 15 SALE-PRICE PIC 9(013)V99. 15 STAFF-PRICE PIC 9(013)V99. 15 TOTAL-PRICE PIC 9(013)V99. The question then becomes what is the best way to achieve this reuse. If you look at a dfdl:textNumberFormat annotation, it is the number pattern that varies. Everything else would be defined once in a dfdl:format annotation and scoped. So it does seem overkill to have a dfdl:textNumberFormat for every number pattern, because the contained properties can not be scoped and must be redeclared each time. I suggest the best reuse mechanism for this scenario is the simple type. In the above example I could declare a PRICE simple type and put the number pattern on that. I therefore agree with Suman. Remove dfdl:textNumberFormat and dfdl:defineTextNumberFormat, add all the properties to dfdl:element and dfdl:simpleType. In practice most will be set in a dfdl:format and scoped, only the number pattern will vary per element or simple type. We should also consider whether the same issue applies to dfdl:calendarFormat and dfdl:escapeScheme. For both these the reuse opportunity is high. There is likely to be just one escape scheme per data format. There is likely to be a small number of calendar formats per data format (eg, one for a date, one for a time, one for a timestamp). But in the latter case, it is typically just the calendarPattern that would vary, the rest of the properties would be set once. I suggest that whatever we adopt for text numbers we also adopt for calendars, for consistency. Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh(a)uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Suman Kalia/Toronto/IBM@IBMCA To: Alan Powell/UK/IBM@IBMGB, Steve Hanson/UK/IBM@IBMGB, Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Cc: dfdl-wg(a)ogf.org Date: 02/02/2010 00:21 Subject: Action Item 049: Built-in specification description and schemas I am trying to create DFDL definition for COBOL copy book and have experienced a usability issue with TextNumberFormat which have to be named and referenced from dfdl:element and dfdl:simpleType annotations. Consider a sample COBOL copy book, attached below, where I have 3 elements having PIC 9999 display clause (a.k.a zoned decimal) and 2 external (standard) decimal. They all have same length but the main difference between them is number is sign which could leading or trailing. As per the V.38 spec, I would have to create a named textNumberFormat for each of the picture clause. The key difference in the named textNumberFormats for these definitions would be numberPattern and rest of the attributes for standard decimal and zoned decimal are going to be same for a particular platform or data definition format. The generated DFDL schema will be containing many occurrences of TextNumberFormat and in the worst case scenario one for each element defined in the COBOL copy book. This is not very usable and also user would have to carefully choose the name for these formats so he can easily identify and distinguish if wants to resue them something like TextNumberStandardLength5SignLeading etc.. 01 CobolTypes. * External decimal ( Zoned decimal) 05 elem9 PIC 9999 DISPLAY. 05 elem9Signed PIC S9999 DISPLAY. 05 elem9SignedLeading PIC S9999 DISPLAY SIGN LEADING. * in DFDL - modeled as standard decimal 05 elem9SignedLeadingSeparate PIC S9999 DISPLAY SIGN LEADING SEPARATE . 05 elem9SignedTrailingSeparate PIC S9999 DISPLAY SIGN TRAILING SEPARATE . Number Format When textNumberRepresentation is ?zoned? only the pattern for positive numbers is used. Only the following pattern characters may be used: '+' to indicate whether the leading or trailing digit carries the overpunched sign, 'V' to indicate the location of an implied decimal point and '0' to indicate the number of digits (including overpunched). The number is '0' characters must match the number of digits in the representation otherwise it is a schema definition error. Better approach would be Add numberPattern to dfdl:element and dfdl:simpleType annotation and rest of the attributes from TextNumberFormat block to either a) dfdl:format only or (b) both dfdl:format and dfdl:element and dfdl:simpleType. Let's discuss this in the DFDL workgroup call tomorrow .. Attached below is a schema coded with the assumption (a) listed above.. <xsd:complexType name="CobolTypes"> <xsd:sequence>  <xsd:element name="elem9" dfdl:ref= "dfdlCobolFmt:CobolZonedDecimalFormat" dfdl:length="4" dfdl:representation="text" dfdl:numberPattern="0000"> <xsd:simpleType> <xsd:restriction base="xsd:short"> <xsd:minInclusive value="0" /> <xsd:maxInclusive value="9999" /> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="elem9Signed" dfdl:ref= "dfdlCobolFmt:CobolZonedDecimalFormat" dfdl:length="4" dfdl:representation="text" dfdl:numberPattern="0000+" > <xsd:simpleType> <xsd:restriction base="xsd:short"> <xsd:minInclusive value="-9999" /> <xsd:maxInclusive value="9999" /> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="elem9SignedLeading" dfdl:ref= "dfdlCobolFmt:CobolZonedDecimalFormat" dfdl:length="4" dfdl:representation="text" dfdl:numberPattern="+0000"> <xsd:simpleType> <xsd:restriction base="xsd:short"> <xsd:minInclusive value="-9999" /> <xsd:maxInclusive value="9999" /> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="elem9SignedLeadingSeparate" dfdl:ref= "dfdlCobolFmt:CobolStandardDecimalFormat" dfdl:length="5" dfdl:representation="text" dfdl:numberPattern="+0000;-00000" > <xsd:simpleType> <xsd:restriction base="xsd:short"> <xsd:minInclusive value="-9999" /> <xsd:maxInclusive value="9999" /> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="elem9SignedTrailingSeparate" dfdl:ref= "dfdlCobolFmt:CobolStandardDecimalFormat" dfdl:length="5" dfdl:representation="text" dfdl:numberPattern="0000+;00000-"> <xsd:simpleType> <xsd:restriction base="xsd:short"> <xsd:minInclusive value="-9999" /> <xsd:maxInclusive value="9999" /> </xsd:restriction> </xsd:simpleType> </xsd:element> ----- Data format Definitions <xsd:defineFormat name="CobolStandardDecimalFormat"> <xsd:format ref:= "tns:BaseTextNumberStandardDecimal" dfdl:lengthKind="explicit" dfdl:lengthUnits="bytes" dfdl:alignment="1" dfdl:alignmentUnits="bytes" dfdl:leadingSkipBytes="0" dfdl:trailingSkipBytes="0" /> </xsd:defineFormat> <xsd:defineFormat name="CobolZonedDecimalFormat"> <xsd:format ref:="tns:BaseTextNumberZonedDecimal" dfdl:lengthKind="explicit" dfdl:lengthUnits="bytes" dfdl:alignment="1" dfdl:alignmentUnits="bytes" dfdl:leadingSkipBytes="0" dfdl:trailingSkipBytes="0" /> </xsd:defineFormat> -- Text number Formats ( added here for reference to identify applicable attributes for standard and zoned decimal) <xsd:defineTextNumberFormat name="ZonedDecimalNumberFormat"> <xsd:textNumberFormat numberCheckPolicy="lax" numberRoundingMode="roundUp" numberZonedSignStyle="asciiStandard" /> </xsd:defineTextNumberFormat> <xsd:defineTextNumberFormat name="StandardDecimalFormat"> <xsd:textNumberFormat numberGroupingSeparator="," numberDecimalSeparator="." numberExponentCharacter="E" numberCheckPolicy="lax" numberInfinityRep="\u221E" numberNanRep= "\uFFFD" numberRoundingMode="roundUp" numberZeroRep="" "" /> </xsd:defineTextNumberFormat> Suman Kalia IBM Toronto Lab WMB Toolkit Architect and Development Lead WebSphere Business Integration Application Connectivity Tools http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.h… Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia(a)ca.ibm.com

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