[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: SAX for Binary Encodings (preserving investment) (ASN.1 an
I wrote: > > > Bob Wyman wrote: > > > > 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. > > > I absolutely agree. Another way of saying this is that the > stream of SAX > callbacks coming from parsing/decoding an encoding of ASN.1 (BER, PER, > EXTENDED-XER) has to be exactly the same stream, for a given > schema and a > given instance, regardless of the encoding rules in use (BER, PER, > EXTENDED-XER), and has to be the same stream as would be > generated by a > "normal" SAX parser parsing the XML document. It must be possible to > replace a normal SAX parser used by an application with an ASN.1 > parser/decoder for either XML or binary encodings with > minimum changes to > the application code. This will give us the interoperability we need > between the two worlds. And it is not just about attributes vs. elements. It is also about: - mixed content, - variable-order sequences (those consisting in a group of elements whose order in the instance "doesn't matter" (*)), - removing wrappers around multiple occurrences of things, - CHOICEs corresponding to XSD's type derivation hierarchies, - CHOICEs corresponding to XSD's element substitution groups, - CHOICEs corresponding to XSD's unions, - "SEQUENCE OF"s corresponding to XSD's lists, - support of wildcards, and so on. All these features (and others) are supported by an XER-specific notation in the ASN.1 schema, which affects EXTENDED-XER encodings but does not affect BER/PER encodings. However, a SAX XMLReader over BER/PER should behave *as if* BER/PER encodings contained some representation of the above things as EXTENDED-XER does. Alessandro Triglia (*) or "matters", depending on people's views and use cases (ASN.1 supports both views/use cases). > > Alessandro Triglia > > > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://lists.xml.org/ob/adm.pl> > >
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