[DFDL-WG] Consolidated Notes including both DFDL WG Call 2018-08-07 along with other recent clarification email threads
Mike Beckerle
mbeckerle.dfdl at gmail.com
Fri Aug 17 11:15:39 EDT 2018
I discovered that erratum 5.10 already includes modified wording equivalent
to one of the things discussed:
5.10 says: Add a clause in 9.4.2.2 and 9.4.2.3 so that the statement about
optional occurrences says "If dfdl:emptyValueDelimiterPolicy *is in effect
and* is not 'none'...", as the words today do not cover cases when it is
ignored (no initiator or terminator).
Our discussion in this thread is slightly different wording:
Sections 9.4.2.2 and 9.4.2.3
The phrase "Optional occurrence: If dfdl:emptyValueDelimiterPolicy is
not 'none'*[12]* <http://daffodil.apache.org/docs/dfdl/#_ftn12>," Change
to "Optional occurrence: if dfdl:emptyValueDelimiterPolicy is applicable
and is not 'none',...." (retaining the footnote)
I prefer the terminology "is applicable" here, as "in effect" can have the
connotation of just "is set".
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are
subject to the OGF Intellectual Property Policy
<http://www.ogf.org/About/abt_policies.php>
On Wed, Aug 15, 2018 at 10:12 AM Steve Hanson <smh at uk.ibm.com> wrote:
> Mike, thanks for writing this up.
>
> I am in the process of incorporating it into the minutes of the WG call.
> There is one paragraph that on re-reading and comparing with what is in the
> spec already, I am not so sure about.
>
> Section 9.2.2
> The sentence: "The *empty representation* is special in DFDL,
> because when parsing it is this condition that can trigger the creation of
> a default value for an element occurrence." replace with: "The empty
> representation is special in DFDL because when parsing it it is used to
> determine when default values are created in the Infoset, and when optional
> recurring elements are omitted from the Infoset. The empty representation
> can require initiators or terminators be present so as to enable data
> formats to explicitly distinguish empty-string/hexBinary values (which
> might cause default values to be used) from emptiness meaning the absence
> of any representation."
> (This is to clarify an error of omission - prior language suggested
> that EVDP is only relevant when the element has a default value, because
> only that need was mentioned.)
>
> What is the significance of 'optionally recurring elements'? I would have
> thought that is just 'optional occurrences' as it applies to (0,1) elements
> too.
>
> Actually I'm not convinced that clause is needed at all. The point of this
> paragraph is to call out defaulting. Not adding occurrences to the infoset
> happens for absent and missing occurrences too, as described in later
> paragraphs.
>
> I would prefer:
>
> "The empty representation is special in DFDL because when parsing it is
> used to determine when default values are created in the Infoset. The empty
> representation can require initiators or terminators be present so as to
> enable data formats to explicitly distinguish occurrences with empty
> string/hexBinary values from occurrences that are missing or are absent."
>
> 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 at uk.ibm.com* <smh at uk.ibm.com>
> tel:+44-1962-815848
> mob:+44-7717-378890
> Note: I work Tuesday to Friday
>
>
>
> From: Mike Beckerle <mbeckerle.dfdl at gmail.com>
> To: DFDL-WG <dfdl-wg at ogf.org>
> Date: 07/08/2018 18:46
> Subject: [DFDL-WG] Consolidated Notes including both DFDL WG Call
> 2018-08-07 along with other recent clarification email threads
> Sent by: "dfdl-wg" <dfdl-wg-bounces at ogf.org>
> ------------------------------
>
>
>
> This message includes two parts.
>
> Part 1 is the things we discussed on the DFDL WG Call of 2018-08-07.
> Part 2 is the other recent emails where the conclusion from the email
> thread is repeated here for finalization/refinement, and for consolidation
> so all these changes can be considered together.
>
> ================================
>
> Part 1 - Discussed on the call.
> *Re: [DFDL-WG] Clarification discussion points for next call(s) - DFDL
> Spec issues around nil, empty, normal, absent, defaulting, and separator
> suppression.*
> Dated August 2nd
>
> Conclusions:
>
> Section 9.3.1.1
> Delete phrase "...this of course implies that....". Note that there is
> already a correction to create numbered bullets of 3 sentences. The
> sentence containing this phrase will be bullet #3 of that list.
>
> Section 9.4
> Item 2 under "For elements and element refs:" Change to: "dfdl:element
> following property scoping rules, which includes establishing
> representation as described in Section 9.3.2 and conversion to element type
> for simple types."
>
> Section 9.3.2
> The phrase "The first step is to see if the content is trivaill of
> length zero." Change to: "The first step is to see if the SimpleContent or
> ComplexContnet region is of length zero as a first approximation."
> The bullet "delimited => length is zero (delimiter is immediately
> encountered)" Insert "in scope" after the open parenthesis.
>
> Section 9.4.2.3.
> We agreed that the paragraphs beginning with "For both required and
> optional..." need to be better tied to the material above. Wording TBD -
> pending Steve Hanson doing some tests on IBM DFDL.
>
> ============================
>
> Part 2 - Below are conclusions from the prior email threads. This is for
> email review in lieu of discussion on this week's call.
> *Re: [DFDL-WG] clarification: on suppressed ZL string/hexBinary - do we
> keep variable assignments?*
> Of Aug 6 (last date in the thread)
>
> These corrections apply:
>
> Sections 9.4.2.2 and 9.4.2.3
> The phrase "Optional occurrence: If dfdl:emptyValueDelimiterPolicy is
> not 'none'*[12]* <http://daffodil.apache.org/docs/dfdl/#_ftn12>," Change
> to "Optional occurrence: if dfdl:emptyValueDelimiterPolicy is applicable
> and is not 'none',...." (retaining the footnote)
>
> Section 9.4.2
> Before the final phrase "There are three main cases to consider:"
> Insert this sentence: "The sections below indicate when an item is added to
> the infoset, and whether it has a default or other value. If there is no
> processing error then regardless of whether an item is added to the infoset
> or not, any side-effects due to dfdl:discriminator statements evaluating to
> true, or dfdl:setVariable statements, are retained."
>
> Section 12.2
> For property emptyValueDelimiterPolicy, before the phrase "It is a
> schema definition error if...", insert this sentence: "The value of
> dfdl:emptyValueDelimiterPolicy should only be checked if there is a
> dfdl:initiator or dfdl:terminator in scope. If so, and
> dfdl:emptyValueDelimiterPolicy is not set, it is a schema definition error.
> If dfdl:initiator is not "" and dfdl:terminator is "" and
> dfdl:emptyValueDelimiterPolicy is 'terminator' it is a schema definition
> error. If dfdl:terminator is not "" and dfdl:initiator is " and
> dfdl:emptyValueDelimiterPolicy is 'initiator' it is a schema definition
> error."
>
> Section 13.16
> For property nilValueDelimiterPolicy, before the phrase "It is a
> schema definition error if...", insert this sentence: "The value of
> dfdl:nilValueDelimiterPolicy should only be checked if there is a
> dfdl:initiator or dfdl:terminator in scope. If so, and
> dfdl:nilValueDelimiterPolicy is not set, it is a schema definition error.
> If dfdl:initiator is not "" and dfdl:terminator is "" and
> dfdl:nilValueDelimiterPolicy is 'terminator' it is a schema definition
> error. If dfdl:terminator is not "" and dfdl:initiator is " and
> dfdl:nilValueDelimiterPolicy is 'initiator' it is a schema definition error
> ."
>
> Section 9.2.2
> The phrase "the occurrence's content in the data..." replace with
> "the occurrence's SimpleContent or ComplexContent region in the data..."
> The sentence: "The *empty representation* is special in DFDL,
> because when parsing it is this condition that can trigger the creation of
> a default value for an element occurrence." replace with: "The empty
> representation is special in DFDL because when parsing it it is used to
> determine when default values are created in the Infoset, and when optional
> recurring elements are omitted from the Infoset. The empty representation
> can require initiators or terminators be present so as to enable data
> formats to explicitly distinguish empty-string/hexBinary values (which
> might cause default values to be used) from emptiness meaning the absence
> of any representation."
> (This is to clarify an error of omission - prior language suggested
> that EVDP is only relevant when the element has a default value, because
> only that need was mentioned.)
>
> *Re: [DFDL-WG] Clarification needed: separator for empty sequence*
> Of Aug 2
>
> Section 14.2
> For property dfdl:separator. The sentence: "Separators occur in the
> data either before, between or after all occurrences of the elements or
> groups that are the children of the sequence." replaced with "Separators
> occur in the data either before, between or after all occurrences of
> *represented* elements (that is, elements without the dfdl:inputValueCalc
> property) or model groups that are the children of the sequence. Elements
> with dfdl:inputValueCalc have no representation in the data stream, and so
> never have separators. Children of a sequence that are model groups are
> always separated, even if they are empty (meaning have no children of their
> own - which is allowed for sequence groups), or both the model group child
> and its contained children occupy zero-length in the data stream."
> (note: Some of the above is redundant with stipulations in the
> dfdl:inputValueCalc property description, but I believe it is wise to have
> this little redundancy.)
>
> ======================
>
> These email threads are mentioned here to indicate that they are resolved
> by one or another of the above corrections:
>
> *Re: [DFDL-WG] clarification needed - ambiguity about empty string and
> optional element*
> Of Aug 2
> *Re: [DFDL-WG] Spec correction ? - Section 9.3.2.1 - second list missing
> "empty" representation*
> Of Aug 2
>
> -----------
>
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
> *www.tresys.com* <http://www.tresys.com>
> Please note: Contributions to the DFDL Workgroup's email discussions are
> subject to the *OGF Intellectual Property Policy*
> <http://www.ogf.org/About/abt_policies.php>
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