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   Re: [xml-dev] SAX for Binary Encodings (preserving investment) (ASN.1 an

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Ed Day wrote:
> Binary encodings don't have attributes, processing
> instructions, etc..  So how are we going to fire non-
> existent events?  This does not make it any less SAX
> compliant.
     However, ASN.1 X.694 defines encoding control notation 
that allows the definer of a schema to say that when the 
encoding format is XML, a certain element should be treated 
as an attribute and the constraints on attributes should 
apply (i.e. SIZE(0..1), etc.). I argue that if something is 
marked to be an attribute when converted to XML, then it 
should be marked as an attribute when it is passed through an 
interface like SAX which is commonly used to process XML-like 
data. If this were not the case, then binary data would look 
different to the user of SAX when it was read directly via 
SAX rather than being read from a chunk of XML written by the 
XML encoder. This would be silly and unproductive.
     Implementors of ASN.1 defined encodings who provide SAX 
interfaces *MUST* ensure that the full richness of the XML 
model is exposed to SAX in just the same way that it is 
supported by the XML encoders. If you don't do this, then, to 
get consistency, we will be forced to serialize the binary 
streams to XML prior to passing them to SAX and we won't use 
your SAX interface.

>This does not make it any less SAX compliant.
    Of course, passing data without attributes doesn't make 
the system any "less SAX compliant." However, it certainly 
does end up in a result that it *not* what one would expect. 
The encoding controls defined in X.694 are there to ensure 
that ASN.1 defined binary encodings "look like" XML in all 
contexts in which "looking like" XML is important. SAX is one 
of those contexts. Thus, a SAX interface on such data streams 
that did not pass attribute information for things which are 
flagged as attributes in the schema should be considered 
wrong, bad, not in the spirit of X.694, not useful, etc. even 
if it otherwise appears to conform to the SAX interface. 
Either do it right or don't do it at all. Please.

     bob wyman


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