June 2012 - dfdl-wg - lists.ogf.org

AUTO: Sunil Dandamudi is out of the office (returning 06/28/2012)
by Sunil Dandamudi 27 Jun '12

27 Jun '12

I am out of the office until 06/28/2012. Note: This is an automated response to your message "dfdl-wg Digest, Vol 72, Issue 24" sent on 6/27/12 10:00:02. This is the only notification you will receive while this person is away.

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Re: [DFDL-WG] test case length_delimited_12_03
by Steve Hanson 27 Jun '12

27 Jun '12

After discussion by the DFDL WG, it was noted that applying a default lengthKind of 'delimited' to all the elements in a DFDL model for CSV would cause the root element to be using 'delimited' without any delimiters in scope. Further spec section 12.3.2 specifically allows for end-of-data being a valid reason for successfully ending a delimited scan. Therefore it is not correct for 'delimited' and no delimiters to give rise to an SDE. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Steve Hanson/UK/IBM To: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Cc: dfdl-wg(a)ogf.org, dfdl-wg-bounces(a)ogf.org Date: 21/06/2012 15:49 Subject: Re: [DFDL-WG] test case length_delimited_12_03 Hi Mike I think the test case can be explained by the fact that IBM DFDL does not yet support dfdl:lenghKind = 'endOfParent', hence any test case would try to use 'delimited'. I don't have an issue with saying that encountering dfdl:lengthKind 'delimited' while parsing but having no delimiters in scope, is an SDE. It's almost certainly an indication the model is wrong. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: dfdl-wg(a)ogf.org Date: 21/06/2012 13:20 Subject: [DFDL-WG] test case length_delimited_12_03 Sent by: dfdl-wg-bounces(a)ogf.org IBM published a set of test cases for DFDL. One of them is length_delimited_12_03. I want to discuss whether this is in fact the behavior we want for DFDL. In this example, there is data "abcde", and the default format is lengthKind="delimited", but no delimiters are defined anywhere.  <xs:element name="myStringSeq2" dfdl:lengthKind="explicit" dfdl:length="5"> <xs:complexType> <xs:sequence dfdl:initiatedContent="no" dfdl:separatorPosition="infix" dfdl:sequenceKind="ordered" dfdl:separator="" > <xs:element name="Test1" type="xs:string"> </xs:element> </xs:sequence> </xs:complexType> </xs:element> The only way for this to parse is for the inner element Test1 to be delimited by the end-of-data coming from the explicit surrounding box created by the myStringSeq2. I thought this should be a SDE because no delimiter is defined anywhere. I see that it can work, if we adopt a policy that delimited, but with no delimiters, means delimited by end-of-available-data. But, I thought that is what lengthKind="endOfData" is for. Can anyone comment as to why the lengthKind="delimited" but with no delimiter strings defined should NOT be an SDE? -- dfdl-wg mailing list dfdl-wg(a)ogf.org https://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 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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OGF DFDL WG Call Minutes 2012-06-26
by Steve Hanson 26 Jun '12

26 Jun '12

Please find minutes from the above call on GridForge at https://forge.ogf.org/sf/docman/do/downloadDocument/projects.dfdl-wg/docman… Errata document is now at v010 here: http://forge.gridforum.org/sf/go/doc16280?nav=1 Regards Steve Hanson Architect, DFDL, IBM SWG Co-Chair, OGF DFDL Working Group Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

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OGF DFDL WG Call Agenda 2012-06-26
by Steve Hanson 26 Jun '12

26 Jun '12

Please find agenda for the above call on GridForge at https://forge.ogf.org/sf/docman/do/downloadDocument/projects.dfdl-wg/docman… Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

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OGF DFDL WG Call Minutes 2012-06-19
by Steve Hanson 26 Jun '12

26 Jun '12

Please find minutes from the above call on GridForge at https://forge.ogf.org/sf/docman/do/downloadDocument/projects.dfdl-wg/docman… Regards Steve Hanson Architect, DFDL, IBM SWG Co-Chair, OGF DFDL Working Group Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

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Updated DFDL 1.0 Errata document
by Steve Hanson 22 Jun '12

22 Jun '12

The errata document is now at Version 010 and reflects all agreed errata up until 19th June 2012. https://forge.ogf.org/sf/docman/do/downloadDocument/projects.dfdl-wg/docman… Change bars show changes since Version 008. To view change bars but without formatting boxes, select 'Final with Markup' and under 'Show' uncheck 'Formatting'. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

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test case length_delimited_12_03
by Mike Beckerle 21 Jun '12

21 Jun '12

IBM published a set of test cases for DFDL. One of them is length_delimited_12_03. I want to discuss whether this is in fact the behavior we want for DFDL. In this example, there is data "abcde", and the default format is lengthKind="delimited", but no delimiters are defined anywhere.  <xs:element name=*"myStringSeq2"* dfdl:lengthKind=*"explicit"* dfdl:length=*"5"*> <xs:complexType> <xs:sequence dfdl:initiatedContent=*"no"* dfdl:separatorPosition=*"infix"* dfdl:sequenceKind=*"ordered"* dfdl:separator=*""* > <xs:element name=*"Test1"* type=*"xs:string"*> </xs:element> </xs:sequence> </xs:complexType> </xs:element> The only way for this to parse is for the inner element Test1 to be delimited by the end-of-data coming from the explicit surrounding box created by the myStringSeq2. I thought this should be a SDE because no delimiter is defined anywhere. I see that it can work, if we adopt a policy that delimited, but with no delimiters, means delimited by end-of-available-data. But, I thought that is what lengthKind="endOfData" is for. Can anyone comment as to why the lengthKind="delimited" but with no delimiter strings defined should NOT be an SDE?

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Re: [DFDL-WG] Possible DFDL spec errata - errata taken
by Steve Hanson 20 Jun '12

20 Jun '12

Errata taken for both this issues in this email thread: 2. Is parent/child alignment rule too strict? Yes, remove rule altogether. 3. Does DFDL need to support signed integer types with lengthUnits 'bits'? Yes, add support for signed integer types. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Steve Hanson/UK/IBM To: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Cc: dfdl-wg(a)ogf.org Date: 29/05/2012 19:08 Subject: Re: [DFDL-WG] Possible DFDL spec errata "Only the first child (aka "first anything" in the structure) gets aligned and can have the conflict of its local alignment specification, and that of some enclosing structure. " Yes that's what I was calling the first child rule. In DFDL terms, would that also mean that the first child can not have any leading skip, as that would throw off the alignment? We also need to bear in mind that we have complex element, sequence, first child element, all of which have alignment. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org Date: 29/05/2012 18:51 Subject: Re: [DFDL-WG] Possible DFDL spec errata I don't get it. Only the first child (aka "first anything" in the structure) gets aligned and can have the conflict of its local alignment specification, and that of some enclosing structure. If some later field gets aligned, then that's not relevant at all, as you treat that normally as another instance of alignment recursively (it could, afterall, also be a structure with sub fields having their own alignments, etc.) Is that the "first child rule" ...mike On Tue, May 29, 2012 at 1:45 PM, Steve Hanson <smh(a)uk.ibm.com> wrote: Hi Mike The one rule that C does apply is the first child rule. C does not allow padding before the first child in a struct, so the alignment of the first child must not be greater than the alignment of the parent. But it won't complain if the third element's alignment is greater than the parent's, for example. So the rule needs to be relaxed, I think the only question is whether we drop the rule altogether or go with the first child rule. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org Date: 29/05/2012 18:08 Subject: Re: [DFDL-WG] Possible DFDL spec errata On Tue, May 29, 2012 at 12:03 PM, Steve Hanson <smh(a)uk.ibm.com> wrote: These were on the agenda for today's cancelled call. 2. Is parent/child alignment rule too strict? Spec property description for alignment says "The alignment of a child component must be less than or equal the alignment of its parent element, sequence or choice". Experiments with creating DFDL schema from C structures have shown that this rule is violated. It seems unnecessary. Specifically, C ensures that the alignment of objects in a repeating structure is preserved by rounding up the length of the structure, rather than aligning it. I think the point of this restriction was to insure that we didin't have conflicting alignments. Where the begining of the structure was aligned, say 64, but the first element was aligned at some incompatible boundary. Like 128. It would almost certainly be an error if the first element in a structure has a larger alignment constraint than the overall structure, and the user should pick where to place the constraint, and not constrain both, except when the constraints on one are implied by the constraints of another. Example: I have a 4k page aligned structure. The first element is some type of double float coming from a global simple type def. The global simple type definition that says my specific kind of double floats are always 8-byte aligned. The 4k page is obviously 4096 byte aligned. There should be no conflict here. The page alignment "Wins" and the begining of the structure is 4k aligned, and that satisifies the 8-byte alignment of my specialized double float. The point of having any restriction at all, is to catch conflicts. Eg., what if I had something that was 64-byte aligned, and I put it inside a structure that has only 2-byte alignment....., this is probably an error. If this isn't going to catch any errors, then this restriction is unnecessary. 3. Does DFDL need to support signed integer types with lengthUnits 'bits'? Spec only allows unsigned integers to have lengthUnits 'bits', but it is possible in C structures to delare bit fields for signed integers. They behave like two's complement. It looks like the spec is being too restrictive in its types for 'bits'. I missed this over restriction. Signed are definitely needed. -- 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 -- 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 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] String literal syntax for hexBinary ?? - need DFDL string literal constructor
by Steve Hanson 19 Jun '12

19 Jun '12

Agreed today that such a function is needed, errata taken. Proposals for function name welcome. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Steve Hanson/UK/IBM To: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Cc: dfdl-wg(a)ogf.org Date: 20/04/2012 09:04 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - need DFDL string literal constructor I think what we need is a function that takes a string and returns the equivalent DFDL string literal. It looks for the characters that need cause problems (%, space) and replaces them (with '%%' and '%SP;' respectively), and if the string is the empty string replaces it with '%ES;'. I think it's just those that are problematic, as all other characters will be interpreted correctly (the entity syntax is primarily just for convenience of data entry). Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org Date: 19/04/2012 14:27 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof Ok, these are very good reasons. So we need the function(s) in our xpath library to make doing this same substitution easy (e.g., the replace function discussed elsewhere in this thread would do it I believe because all we have to do is replace "%" with "%%".) On Thu, Apr 19, 2012 at 9:20 AM, Steve Hanson <smh(a)uk.ibm.com> wrote: The reason that % needs escaping is that most entities start with just % - eg %NUL; - and it means we have simple rules - you want to use a literal % then escape it. and if you use just % then we expect to see an entity next. If we don't do it this way, then we will not be able to extend the list of entities in the future without breaking existing expressions, and we won't detect the very common error of leaving off the trailing semi-colon by mistake.. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: Tim Kimber/UK/IBM@IBMGB, dfdl-wg(a)ogf.org Date: 19/04/2012 14:01 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof I don't think % by itself requires any escaping. There is only a need for escaping when the characters after the % match the syntax for one of our entities. I don't expect Dfdl:terminator="%done%" to require any escaping. On Apr 19, 2012 7:16 AM, "Steve Hanson" <smh(a)uk.ibm.com> wrote: Tim, thinking some more on this: - A DFDL expression is sometimes allowed to *return* a DFDL String Literal. In this case, the returned value is an xs:string that conforms to the DFDL String Literal syntax That is indeed how properties like initiator, terminator and separator behave today. But there is a problem. Let's say I have dynamically defined a separator at the start of my data. The value in the data is %. My dfdl:separator expression therefore returns %. That will give an error as a badly formed DFDL entity. DFDL string literal rules say that you must use %% to represent a single % character. The expression itself can work around this by checking for % and if so substituting %%, but that's a bit unfriendly especially as fn:replace() is not in the DFDL XPath subset - I think this is because it comes under this category http://www.w3.org/TR/xpath-functions/#string.match and not http://www.w3.org/TR/xpath-functions/#substring.functions. Perhaps we should include fn:replace() or provide a DFDL function that handles %? I started wondering whether these properties' expression should return a list of String. I can envisage no format that has in its data a value that contains DFDL entity syntax and intends it to mean a DFDL entity! That is too contrived to be real. However I can certainly envisage an expression like this: dfdl:separator = "{if ../version eq 1 then %CR;%LF; else %LF;}" So I think String is not sufficient and DFDL String Literal must be allowed. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Tim Kimber/UK/IBM To: Steve Hanson/UK/IBM@IBMGB Cc: Mike Beckerle <mbeckerle.dfdl(a)gmail.com>, dfdl-wg(a)ogf.org Date: 19/04/2012 11:32 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof I agree with all of that. One refinement, though. I don't think it's necessary to *require* an implementation to auto-cast the result of a DFDL Expression into the target type. If an implementation wants to be picky about the return type AND issue a clearly-worded Schema Definition Error stating what the problem is then I think we should allow it. Arguably, this would reduce the portability of DFDL schemas, but there is precedent for defining a portable subset of a language while allowing conveniences for users who don't need portability ( e.g. ANSI 'C' ). We already take that line for the regular expression syntax, so there is precedent for this in the DFDL specification too. 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 Cc: Mike Beckerle <mbeckerle.dfdl(a)gmail.com>, dfdl-wg(a)ogf.org Date: 19/04/2012 11:04 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof Hi Tim Firstly, both your bulleted assertions are correct, but your conclusion is not. Secondly, let me flesh out my earlier reply about constructor functions. The last paragraph of Section 23 says: "The result of evaluating the expression must be a single atomic value of the type expected by the context, and it is a schema definition error otherwise". This is where the XPath constructors come into play. Eg: <element name="myHexBin" type="xs:hexBinary" dfdl:inputValueCalc="{ xs:hexBinary (...) }"/> These xs: constructors, plus the special fn:dateTime() constructor that DFDL adds, allow the correct types to be created. Note that you don't always need the constructors. An expression that returns a quoted value is returning an XPath string literal so that is automatically xs:string. An expression that returns an unquoted number is returning an XPath number literal so that can be xs:decimal, xs:integer, xs:double (depends whether the number contains a '.' or 'e' or 'E'). This is described here: http://www.w3.org/TR/xpath20/#id-literals So simply returning the literal 'DEADBEEF' will return an xs:string and if the context requires xs:hexBinary that is a schema definition error according to DFDL spec. A clarification is worth while though. Take the following expression: {if ../type eq 'A' then 10000 else 20000}. That returns xs:integer. - What if my context was xs:decimal? xs:integer is a restriction of xs:decimal so the value will always be in range, so is that 'auto-cast' allowed? - What if my context was xs:long or another restriction of xs:integer? The value may or may not be in range, so is that 'auto-cast' iff value in range? I think that we should auto-cast when type restrictoions are involved, and clarify that in the spec. We *could* change the spec to say that the result of the expression is always automatically cast to the type expected by the context. That takes some of the burden off the modeler and makes it much more likely that expressions written by XPath novices will return the correct results. But it could also hide accidental errors. Note this proposal I shall call (d) as it not the same as Mike's (c). If we made this change, then returning the literal 'DEADBEEF' for xs:hexBinary would succeed. I don't think it affects the desire for expressions to be statically type checkable - because it is known whether type X can be cast to type Y, so a cast mismatch can be statically detected. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 From: Tim Kimber/UK/IBM To: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Cc: dfdl-wg(a)ogf.org, dfdl-wg-bounces(a)ogf.org, Steve Hanson/UK/IBM@IBMGB Date: 19/04/2012 09:35 Subject: Re: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof I'm pretty sure that the rules are: - DFDL expressions must not *contain* DFDL String Literals. They must be valid XPath 2.0 expressions except that the list of allowable function names includes the DFDL extension functions. - A DFDL expression is sometimes allowed to *return* a DFDL String Literal. In this case, the returned value is an xs:string that conforms to the DFDL String Literal syntax. But that does not apply to your example because the dfdl:inputValueCalc must return a value ( an XML value ) that is valid for the type of the element. I think that corresponds to your answer a) ; 'DEADBEEF' is a valid xs:hexBinary lexical value. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert(a)uk.ibm.com Tel. 01962-816742 Internal tel. 246742 From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org Date: 19/04/2012 07:42 Subject: [DFDL-WG] String literal syntax for hexBinary ?? - Re: String literals - various usage patterns thereof Sent by: dfdl-wg-bounces(a)ogf.org What is the DFDL string literal syntax for a hexBinary type value? E.g., I want a hex binary whose value is the 4 bytes described by this hex: DE AD BE EF. <element name="myHexBin" type="xs:hexBinary" dfdl:inputValueCalc="{ ... }"/> So, what can one syntactically put, for literal constant values, in the input value calculation expression? Note that this is legal pure (non-DFDL) XSD (I think) <element name="aHexBin" type="xs:hexBinary" fixed="DeadBeef"/> That is, the fixed/default are allowed and one specifies these values as just strings of hex digits. Notice no special escaping or anything. You just use a string that just so happens to contain hex digits. I think there are three possibilites (a) we allow "DEADBEEF" i.e., because the type of the expression is hexBinary, a string is cast to hexBinary by interpreting it as hex nibbles. (b) we require a special kind of string literal - a bytes-only string literal, so for example: "%#rDE;%#rAD;%#rBE;%#rEF;" is the way you create 4 bytes. If you just put characters, then that's a processing error - like a cast failure. Only raw-bytes allowed. (c) Anything you return from the expression is converted to a hexBinary by unparsing it to bytes (using current properties), then using the bytes as the hexBinary data. So you could have an expression that returns a double, and that would create 8 bytes if representation="binary". In this case the decimal number 3735928559 (hex 0xdeadbeef) as a binary bigEndian int would produce the 4 bytes I want. -- dfdl-wg mailing list dfdl-wg(a)ogf.org https://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 -- 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 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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OGF DFDL WG Call Agenda 2012-06-18/19 - updated
by Steve Hanson 18 Jun '12

18 Jun '12

Please find agenda for the above call on GridForge at https://forge.ogf.org/sf/docman/do/downloadDocument/projects.dfdl-wg/docman… We have quite a few items building up, so there are two calls this week, with a single agenda as per link. Mon 18th @ 16:00 UK (extra call) Tues 19th @ 15:00 UK (regular time) The document has been updated with the results of the 18th call. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

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