[dfdl-wg] alternate syntax for DFDL annotations

[Steve Hanson]

I can't say I am over keen on this, because
- you will end up with odd rules where some properties can be attributes
and some can't, which will confuse users.
- you have to invent errors and/or overide behaviour when you get a clash
between attribute and annotation
- (minor) it makes the job of any software that instantiates a dfdl memory
model harder

If we do adopt this then #2 is preferable.

Regards, Steve

Steve Hanson
WebSphere Business Integration Brokers,
IBM Hursley, England
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848


                                                                           
             "Myers, James D"                                              
             <jim.myers at pnl.go                                             
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                                       RE: [dfdl-wg] alternate syntax for  
             02/03/2005 17:35          DFDL annotations                    
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





I agree - I think I like #2. I know at one point in the past we had
complaints when we tried to use attributes with namespaces - it may just
have been that parsers weren't dealing with them correctly early on.
Whatever it was, option 2 would provide a work around as well as helping
us keep a single 'canonical' form for DFDL.

 Jim

> -----Original Message-----
> From: owner-dfdl-wg at ggf.org [mailto:owner-dfdl-wg at ggf.org] On
> Behalf Of Martin Westhead
> Sent: Wednesday, March 02, 2005 12:16 PM
> To: Mike Beckerle
> Cc: dfdl-wg at gridforum.org
> Subject: Re: [dfdl-wg] alternate syntax for DFDL annotations
>
>
> Hi Mike,
>
> This is interesting I wasn't aware you could do this. My
> concern would
> be if it turned out the schema tools couldn't handle it but I
> tried XML
> Spy which seems to just ignore the extra annotations.
>
> So I'd be happy to use them. As you point out we will need both these
> and annotations so we are left with a choice. Either we:
>
>    1. Specify some (most) dfdl additions in this non-native attribute
> form and use annotations when required or
>
>    2. We specify everything as annotations but allow this form as a
> systematic short hand.
>
> I think I prefer (2). The sort of thing I have in mind is making the
> annotation syntax look like:
>
> <xs:element name="foo" type="xs:string">
>    <annotation>
>      <appinfo>
>         <dfdl:attributes dfdl:repType="text"
>                          dfdl:charset="UTF-8"
>                          dfdl:repLength="10"/>
>      </appinfo>
>    <annotation
> </xs:element>
>
> And then this be directly equivalent (and trivially transformed
> into/from) what you had before:
>
> <xs:element name="foo"
>              type="xs:string"
>              dfdl:repType="text"
>              dfdl:charset="UTF-8"
>              dfdl:repLength="10"/>
>
> I'm not sure if it matters that much but it seems like it might be
> neater if everything could be represented in the same form.
>
> Also there may be times when you would like to use the
> annotation form
> because you have a bock of stuff that could be reused multiple times.
> Once your annotations have become attributes in the main
> schema they are
> more intimately tied to it.
>
> Cheers,
>
> Martin
>
>
>
> Mike Beckerle wrote:
> > Up til now we've considered DFDL annotations only as inside the
> > appinfo
> > context. However, we should consider whether we should use
> non-native
> > attributes as well or
> >
> > as an alternative: E.g., simple DFDL rep properties could also be
> > expressed like this:
> >
> >     <xs:element name="foo"
> >
> >                 type="xs:string"
> >
> >                 dfdl:repType="text"
> >
> >                 dfdl:charset="UTF-8"
> >
> >                 dfdl:repLength="10"/>
> >
> >
> >
> > This has the advantages of compactness, and is a fully
> supported way
> > of
> > extending XML Schema. That is, using non-native attributes is a
> > supported extension idiom. This won't handle things that
> really need the
> > syntactic support of element structure to express their complexity,
> > e.g., things like specifying text delimiters with quoting and
> > escape-sequence specifications. For those we'll still need
> to open an
> > appinfo annotation up. However, for basic things like
> byteOrder and such
> > it is far more attractive syntactically to use non-native
> attributes
> > than appinfo annotations.
> >
> >
> > Comments?
> >
> > ...mikeb
> >
>
>