[dfdl-wg] Transform examples

[Martin Westhead]

Hi Alan,

Thanks for this. Some thoughts/questions/comments that occurred to me 
looking at your example.

First a general point:

  - On one of the calls which I think was just me and the IBMers they 
pointed out quite strongly that the ther "transformation" has other 
connotations that make it very confusing here, Mike also agrees. I think 
we need to choose a different name to avoid such confusion. Mike 
suggested "converters"/"convertions" which is suitably general. I also 
thought about "casting" but I think that's perhaps too specific. Either 
way it would be nice to choose something or our discussions will be 
rather difficult to follow.

(I'll continue to use transform for this email...)

On the example:
  - I was expecting the definition of the input and output types to the 
transform should have equal status. Here it seems that the input is 
specified implicitly in the parameter set it will accept.

  - Why does asciiToInt read byte[]? I would expect it to read at least 
char[] (or probably xs:string, since there is no xs:char). The intent 
would be that you could then compose it with a character converter of 
your choice.

  - In general I think the typing and compositional properties of the 
transformations are the nut that requires cracking here. My proposal is 
that the types should be specified in XML data model at all levels so 
instead of byte[] you would have:

<xs:sequence>
   <xs:element name="anon" type="xs:byte" minOccurs="0" 
maxOccurs="unbounded"/>
</xs:sequence>

that's all for now...

Cheers,

Martin








Chappell, Alan R wrote:
> Third try... No zip, just the 3 files important to the simple transform 
> example....
> 
> ------------------------------------------------------------------------
> *From:* Chappell, Alan R
> *Sent:* Friday, November 19, 2004 1:39 PM
> *To:* dfdl-wg at gridforum.org
> *Subject:* *MJ-REJECTED* Transform examples
> 
> Second try on sending these examples. I've cut the set down to the 3 
> important files so hopefully it will get through this time.
> 
> ------------------------------------------------------------------------
>  *From:* Chappell, Alan R
> *Sent:* Thursday, November 18, 2004 8:47 AM
> *To:* dfdl-wg at gridforum.org
> *Subject:* *MJ-REJECTED* Transform examples
> 
> Here is the example I mentioned yesterday. Look particularly at 
> dfdltransforms.xsd, BasicAsciiIntExp.xsd, and BasicBinIntExp.xsd. Note 
> the "Exp" on those last two files indicate that they are expansions of 
> the information in the original versions of those files. These make a 
> first stab at giving a fully verbose description of the structure and 
> the transforms, i.e., it’s working towards the canonical representation 
> Martin talked about yesterday. The "dfdltransforms" gives the 
> definitions of transforms and their components.
> 
> There are lots of things that can be improved here.
> <<dfdl-examples.zip>>
> Alan R. Chappell
> chappella at battelle.org
> 
> Pacific Northwest National Laboratory
> Battelle Seattle Research Center
> (206) 528-3228
> 
>