[DFDL-WG] Fwd: [dfdl] initiatedContent w/o initiators

[Mike Beckerle]

I really prefer (b) below.

My rationale: replace the hidden group by a real group reference to the
same group. Behavior should not change except for some things show up in
the infoset that would have been omitted.

That principle should hold anywhere it can, hopefully everywhere.

...mike

On Fri, May 31, 2013 at 4:09 AM, Steve Hanson <smh at uk.ibm.com> wrote:

> I agree with Mike's use of a nested choice, I have used this same pattern
> to model a catch-all branch on several occasions.
>
> I would also add that working out which branch of a choice to take can be
> an expensive operation for a DFDL parser, and one where optimisations will
> be applied. The more alike that the branches are, the more likely it will
> be that the parser can optimise the selection.
>
> We still need to answer James' question about schema definition error
> though.  The spec says *"**When the dfdl:hiddenGroupRef property is
> specified, all other DFDL properties are ignored.**"*  which is saying
> other properties are not applicable. In other words, such a sequence is
> present in the schema purely as a device to hide the contents of the group
> that it refers to.  So I think we have a couple of choices when the context
> in which the sequence appears means that it can not be silent about certain
> properties:
>
> a) The use of dfdl:hiddenGroupRef in that context is a schema definition
> error.
>
> b) Go to the model group content of the hidden group and see whether its
> properties satisfy the context.
>
> Regards
>
> Steve Hanson
> Architect, IBM Data Format Description Language (DFDL)
> Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/>
> IBM SWG, Hursley, UK*
> **smh at uk.ibm.com* <smh at uk.ibm.com>
> tel:+44-1962-815848
>
>
>
> From:        Mike Beckerle <mbeckerle.dfdl at gmail.com>
> To:        dfdl-wg at ogf.org,
> Date:        31/05/2013 06:37
> Subject:        [DFDL-WG] Fwd:  [dfdl] initiatedContent w/o initiators
> Sent by:        dfdl-wg-bounces at ogf.org
> ------------------------------
>
>
>
> Forgot to copy the workgroup.
>
> ---------- Forwarded message ----------
> From: *Mike Beckerle* <*mbeckerle.dfdl at gmail.com*<mbeckerle.dfdl at gmail.com>
> >
> Date: Fri, May 31, 2013 at 1:32 AM
> Subject: Re: [DFDL-WG] [dfdl] initiatedContent w/o initiators
> To: "Garriss Jr., James P." <*jgarriss at mitre.org* <jgarriss at mitre.org>>
>
>
> You need two nested choices. Only the inner one uses initiated content.
>
> <xsd:choice>
>     <xsd:choice dfdl:initiatedContent="yes">
>            <xsd:element ref="Date"/>
>
>            <xsd:element ref="From"/>
>
>            <xsd:element ref="MessageId"/>
>
>             <xsd:element ref="Subject"/>
>
>     </xsd:choice>
>
>     <!-- all unknown and unwanted headers -->
>
>     <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/>
>
> </xsd:choice>
>
>
>
> On Thu, May 30, 2013 at 2:49 PM, Garriss Jr., James P. <*
> jgarriss at mitre.org* <jgarriss at mitre.org>> wrote:
> Spec says:
>
>
>
> It is a schema definition error if any children have their dfdl:initiator
> property set to the empty string.
>
>
>
> Does that include a sequence with a hiddenGroupRef?
>
>
>
> For example, part of a schema for email headers is this:
>
>
>
>
> <xsd:choice dfdl:initiatedContent="yes">
>
>
> <xsd:element ref="Date"/>
>
>
> <xsd:element ref="From"/>
>
>
> <xsd:element ref="MessageId"/>
>
>
> <xsd:element ref="Subject"/>
>
>
> <!-- all unknown and unwanted headers -->
>
>
> <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/>
>
>
> </xsd:choice>
>
>
>
> Date, From, and the other headers are all elements with initiators, but
> UnwantedHeadersGroup does not have an initiator (because I don’t know it a
> priori).
>
>
>
> Should this throw an error in a DFDL implementation?  I suspect it should,
> though I hope it shouldn’t.
>
> --
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>
>
>
> --
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | *
> www.tresys.com* <http://www.tresys.com/>
>
>
>
>
> --
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | *
> www.tresys.com* <http://www.tresys.com/>
> --
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>


-- 
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
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