- dfdl-wg - lists.ogf.org

Fwd: Daffodil Infoset File Size Comparison between xml, exi (schema un-aware) and exisa (schema aware) Parsing
by Mike Beckerle 03 Nov '22

03 Nov '22

I thought this might be of interest to the DFDL WG. ---------- Forwarded message --------- From: Thompson, Dave <dthompson@...> Date: Wed, Oct 19, 2022 at 8:41 AM Subject: Daffodil Infoset File Size Comparison between xml, exi (schema un-aware) and exisa (schema aware) Parsing To: users@... Just a heads up to daffodil users for the upcoming Daffodil v3.4.0 release, which will include EXI support. The attached spreadsheet shows the comparison of Daffodil infoset file size when parsing to xml, exi (schema un-aware) and exisa (schema aware) for some of the Daffodil supported schemas. The comparison shows a significant decrease in infoset size between xml and exi (schema un-aware) infoset files and even a greater reduction with exisa (schema aware) infoset files. In most cases of the exisa (schema aware) infoset files, the infoset file is only slightly larger than the original source file. *Source Data* *Daffodil Infoset File Sizes (bytes)* *Data Format* *Source File (bytes)* *XML* *EXI **(Schema Un-aware)* *EXISA **(Schema aware)* 1 bmp 4,264,316 8,529,476 8,528,926 4,264,305 21,600,054 43,200,952 43,200,406 21,600,044 2 cef 4,180 17,880 2,664 2,462 3 gif 950,734 2,353,949 1,916,689 966,667 4 iCal 5,370 47,345 4,606 4,019 5 Jpeg 1,030,473 2,076,278 2,062,048 1,030,817 15,477 47,023 32,181 15,821 6 Jpeg2000 55,399,819 124,654,407 112,527,466 56,438,548 16,298 41,260 33,989 16,590 7 nato-stanag-5516 (FOUO, not public) 1,952 123,818 5,208 2,366 62,464 3,954,922 122,760 71,682 8 Pcap 10,200 35,361 19,363 10,097 104,858,829 225,950,064 208,409,250 104,806,410 9 png 102,400 206,207 204,809 102,340 10 shp 25,048 255,124 42,122 22,505 2,487,024 14,953,554 3,734,330 3,031,262 11 vmf (FOUO, not public) 1,141 39,744 4,840 1,403

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Fwd: [OpenGridForum/DFDL] WIP: Binary num rep (PR #35)
by Mike Beckerle 03 Nov '22

03 Nov '22

I made a asciidoc that is intended to be reviewable on github, but also produce OGF-style (roughly) PDF output. It's a stub for an experimental features document describing new binary number rep and binary calendar reps. Take a look and let me know what you think. https://github.com/OpenGridForum/DFDL/pull/35

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Agenda for OGF DFDL WG Call
by Steve Hanson 07 Sep '22

07 Sep '22

Please find agenda for next call on GitHub at https://github.com/OpenGridForum/DFDL/blob/master/calls/2022-04-07_DFDL-WG-… Regards Steve Hanson IBM Hybrid Integration, Hursley, UK Architect, IBM DFDL<http://www.ibm.com/developerworks/library/se-dfdl/index.html> Co-Chair, OGF DFDL Working Group<http://www.ogf.org/dfdl/> smh(a)uk.ibm.com<mailto:smh@uk.ibm.com> mob:+44-7717-378890 Note: I work Tuesday to Friday

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[Announcement] Apache Daffodil VSCode Extension version 1.1.0
by Mike Beckerle 31 Aug '22

31 Aug '22

The Apache Daffodil community is pleased to announce the release of version 1.1.0 of the Daffodil VS Code Extension. This is the second official release of the Apache Daffodil VS Code Extension. Detailed release notes and downloads are available at: https://daffodil.apache.org/vscode/1.1.0/ The Apache Daffodil VS Code Extension is an open-source extension that utilizes Apache Daffodil to allow users to interactively debug a DFDL schema inside of VS Code. For more information about Daffodil visit: https://daffodil.apache.org/ Regards, The Apache Daffodil Team

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Latest OGF DFDL WG Call Minutes
by Steve Hanson 12 Aug '22

12 Aug '22

Please find minutes from the latest call at https://github.com/OpenGridForum/DFDL/wiki/DFDL-Workgroup-News. Regards Steve Hanson IBM Hybrid Integration, Hursley, UK Architect, IBM DFDL<http://www.ibm.com/developerworks/library/se-dfdl/index.html> Co-Chair, OGF DFDL Working Group<http://www.ogf.org/dfdl/> smh(a)uk.ibm.com<mailto:smh@uk.ibm.com> mob:+44-7717-378890 Note: I work Tuesday to Friday

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binaryNumberRep limitations, xs:decimal and binaryDecimalVirtualPoint
by Mike Beckerle 10 Aug '22

10 Aug '22

Rather long email, apologies in advance. We are encountering many issues where DFDL is too limited in its binary number representations. 6 points are made in this email. To not bury the lead, which is Point 6, I am proposing that we make dfdl:binaryNumberRep an extensible enum, allowing QNames as values so that implementations can extend the set of supported binary number representations. E.g., dfdl:binaryNumberRep='dfdlx:onesComplement', or dfdl:binaryNumberRep='daffodil:signedASN1BERVariableLengthInteger' Point 1: I think this is just a needed clarification. But Points 1 and 2 drove the motivation for this whole discussion. So the description of dfdl:binaryDecimalVirtualPoint says it is allowed on types whose *base* is xs:decimal. That term 'base' is confusing. It can either mean allowed on types derived from xs:decimal, as all the signed and unsigned integer types are. Or it can mean literally <restriction base="xs:decimal"> .... </restriction>. That is, the base attribute of simple type restriction must be xs:decimal, or the type="xs:decimal" directly on the element. I believe the latter is the only thing that makes sense. If dfdl:binaryDecimalVirtualPoint is positive, as this type below is nonsense, as the type says it is an unsigned integer, but the binaryDecimalVirtualPoint says to divide by 100, so that 36000 would become 360.00, a non-integer. The infoset <angle>360.00</angle> makes no sense for an integer type, and would not validate treating the DFDL schema as an XSD. <element name="angle" type="with2DecimalFractionDigits"/> <simpleType name="with2DecimalFractionDigits" dfdl:binaryDecimalVirtualPoint="2">  <restriction base="xs:unsignedShort">  <maxInclusive value="360"/> </restriction> </simpleType> So based on that reasoning, I think we need to improve the clarity and say that dfdl:binaryDecimalVirtualPoint applies only to type xs:decimal alone. (Removing the word 'base' which creates the subtype confusion.) That brings me to the next related point. Point 2: Need for binaryNumberRep='unsignedBinary' We have a use case we cannot express. An angle from 0 to 360 degrees is represented by an unsigned 16 bit binary integer which if dfdl:binaryDecimalVirtualPoint works with that, can represent 000.00 to 360.00. <simpleType name="angle360" dfdl:lengthKind="explicit" dfdl:length="16" dfdl:binaryNumberRep="binary" dfdl:binaryDecimalVirtualPoint="2"> <restriction base="xs:decimal"> <minInclusive value="0"/> <maxInclusive value="360"/> </restriction> </simpleType> However, we have no way to say that the above is to be unsigned binary integer representation. dfdl:binaryNumberRep='binary' means unsigned binary if the type is unsigned, and means signed twos-complement if the type is signed, which xs:decimal is. So my definition of angle360 above is no good, as the maximum positive value is 327.67, which is insufficient. I think we need to revise dfdl:binaryNumberRep to allow for distinguishing binary unsigned from twosComplement signed types, as well as the packed types. Note that the packed types allow 'bcd' which is an unsigned representation, so there is sort of a precedent there for allowing the binaryNumberRep type to be unsigned even if the type is signed-capable. There is already a proposal to add "offsetBinary" as a signed binary integer representation. https://github.com/OpenGridForum/DFDL/issues/7 So I'm suggesting adding "unsignedBinary' as well. So the complete set (so far) would be dfdl:binaryNumberRep: - 'twosComplementBinary' (with legacy 1.0 name 'binary') - 'unsignedBinary' - 'offsetBinary' - 'packed' - 'bcd' - 'ibm4690Packed' Point 3: There are other binary integer representations that will be needed. This table comes from a format specification we use: [image: image.png] Ignore the 'Logical' column above, that's about enums. Ignore the "*" which is just about when a value must be reserved as an in-band null indicator which is the suggested such value. What is called 'Mod Twos Complement' here is what our existing proposed DFDL 2.0 feature calls 'offsetBinary'. So this table suggests the need for 'unsignedBinary' (already mentioned), but also two others: 'signPlusMagnitudeBinary', and 'onesComplementBinary'. Point 4: Zig Zag Integer representation is getting popular There's one other representation I know of which is more recent/modern called zig-zag integers, popularized by google protocol buffers, but it's a clever representation and seemingly used in many places now. *Binary Value* *Zig Zag* 000 0 001 -1 010 1 011 -2 100 2 101 -3 110 3 111 -4 Point 5: Variable Length Binary Integers There are also variable-length integer formats that are not just strings of bits. A common one I have seen is used by ASN.1 BER representation where each byte if its MSB is 1 indicates that the integer extends an additional byte, contributing 7 bits to the value. Unsigned integers are just the concatenation of these bits. Signed integers are handled after the bits are concatenated together. If the first bit of the concatenation is 1, the value is twos complement negative value. Hence, if a positive value would have a first bit of 1, then an additional byte containing 10000000 must be used as the most significant byte so that the first bit will not be 1. There is no way in DFDL to represent such a variable length integer representation and get an integer in the infoset. You have to use a hexBinary byte array. There is a need for a variable-length integer like this to support not only explicit length (used by ASN.1 BER), but implicit length as well. In this case the last byte of the variable length integer does not have the MSB set. Hence, a single byte can represent signed -64 to +63, or unsigned 0 to 127. Outside that range multiple bytes must be used, each byte contributing 7 bits. This suggests a need for several additional dfdl:binaryNumberRep enums. Point 6: Extensibility by implementations is needed here There are many other representations out there as well. I think we should have a convention where there is a core set that all DFDL representations must provide, and a convention by which DFDL implementations can provide additional support. To me, a good way to do this is to allow the enum values for dfdl:binaryNumberRep to be not only regular enums (all of which are reserved) but QName syntax, where the prefix can be for a namespace recognized by an implementation for providing an extended set of binary number representations. (Perhaps the dfdlx: prefix and namespace, or maybe we just allow implementation specific namespaces?) This means of extending enums for existing properties is not part of our existing 'experimental features' conventions, but I propose that it should be added. To me, this is a good way to generally allow property enums to be extended with experimental features in DFDL implementations, and applies to other places such as dfdl:binaryCalendarRep, and numerous other properties where we are finding a need for additional enums and want to add them as experimental features. That was long. Thanks for your consideration. Mike Beckerle Apache Daffodil PMC | daffodil.apache.org OGF DFDL Workgroup Co-Chair | www.ogf.org/ogf/doku.php/standards/dfdl/dfdl Owl Cyber Defense | www.owlcyberdefense.com

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default case needed for choice-by-dispatch
by Mike Beckerle 15 Jul '22

15 Jul '22

I know this feature was discussed at one time. The priority of this has gone up for us substantially, as the idiom in DFDL v1.0 for a choice-by-dispatch to have a default case when the choiceDispatchKey doesn't match any choiceBranchKey is far too complex. This appears to be what is needed:  <group name="discriminateTrue"> <sequence> <annontation><appinfo ...> <dfdl:discriminator>{ fn:true() }</dfdl:discriminator> </appinfo></annotation> </sequence> </group> .... <choice> <choice dfdl:choiceDispatchKey='{ ... dispatch key expr... }'> <sequence dfdl:choiceBranchKey="key1"> <group ref="p:discriminateTrue"/> ... parse the key1 branch .... </sequence> ... <sequence dfdl:choiceBranchKey="keyN"> <group ref="p:discriminateTrue"/> ... parse the keyN branch .... </sequence> </choice>  <element name="invalidKey" ....> ... </element> </choice> ..... The need for a discriminator for the outer choice on every single branch of the inner choice is tedious at best. This is needed because if you don't have this discriminator, then the backtrack will choose the other choice alternative for any failure of a branch, not just no branch key match, and one will get a diagnostic that the branch key was not found when it was found but the subsequent parse failed. This structure is too complex for DFDL schema authors to get right. A way to specify an additional choice branch which is the default to be used on no-match to the other branch keys, is needed. An explicit dfdlx:choiceBranchDefault="yes" is one way to do this. A final choice branch with no dfdl:choiceBranchKey would also work but seems too error-prone for my taste. A default case should be explicitly marked as such, even if we require it to be the last branch. Mike Beckerle Apache Daffodil PMC | daffodil.apache.org OGF DFDL Workgroup Co-Chair | www.ogf.org/ogf/doku.php/standards/dfdl/dfdl Owl Cyber Defense | www.owlcyberdefense.com

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updates to experimental features convention document: enums
by Mike Beckerle 14 Jul '22

14 Jul '22

Updates to allow enumeration properties to be extended with new experimental enum values. See https://github.com/OpenGridForum/DFDL/pull/32 Mike Beckerle Apache Daffodil PMC | daffodil.apache.org OGF DFDL Workgroup Co-Chair | www.ogf.org/ogf/doku.php/standards/dfdl/dfdl Owl Cyber Defense | www.owlcyberdefense.com

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Suggest new lengthKind 'patternMatch' where failure to match is a parse error
by Mike Beckerle 12 Apr '22

12 Apr '22

Apache Daffodil users have had quite a lot of trouble with understanding and proper use of dfdl:lengthKind 'pattern'. This is due to the fact that no match does *not* cause a parse error, but provides a successful parse with length of zero. People generally find this unintuitive given that if they wanted a zero-length match they could have defined their regex to allow a zero-length match. I have made this mistake repeatedly myself when creating DFDL schemas, and supposedly I'm an expert in DFDL. This has been so problematic that I suggest we add an additional enum for lengthKind of 'patternMatch' or maybe 'patternMatchRequired' (I'm open to suggestions for best name here) which is the same as 'pattern', except that failure to match results in a parse error instead of zero length success. I would argue that the existing 'pattern' behavior is badly designed, but it is too late to change it for DFDL v1.0. Rather, for DFDL v2.0 we should add a new correct behavior and call it 'patternMatch' and then we can deprecate the existing lengthKind 'pattern'. Has anyone else had similar difficult experience with lengthKind 'pattern' ? Mike Beckerle Apache Daffodil PMC | daffodil.apache.org OGF DFDL Workgroup Co-Chair | www.ogf.org/ogf/doku.php/standards/dfdl/dfdl Owl Cyber Defense | www.owlcyberdefense.com

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[ANNOUNCE] Apache Daffodil VS Code 1.0.0 Released
by Mike Beckerle 05 Apr '22

05 Apr '22

The Apache Daffodil community is pleased to announce the release of version 1.0.0 of the Daffodil VS Code Extension. This is the first official release of the Apache Daffodil VS Code Extension. Detailed release notes and downloads are available at: https://daffodil.apache.org/vscode/1.0.0/ The Apache Daffodil VS Code Extension is an open-source extension that utilizes Apache Daffodil to allow users to interactively debug a DFDL schema inside of VS Code. For more information about Daffodil visit: https://daffodil.apache.org/ Regards, The Apache Daffodil Team

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