RE: ASN.1 is an XML Schema Language (Fix those lists!)and Bina
John Cowan wrote: > > Alaric B Snell scripsit: > > > The ASN.1 'equivelant' of a normal XML parser would just need to > > support > > BER, which is the current conventional "minimal" encoding. An ASN.1 > > toolkit that supported "BER, PER, CER, DER, XER, and > probably LWER, OER, > > and SER" would be more closely related to an XML parser > that supported > > US-ASCII, UTF-8, UTF-7, UTF-16, EBCDIC, ISO-8859-[1..15], > Shift-JIS, > > Baudot, etc... > > Hardly. Except for some feedback from the encoding > declaration, which can be handled by a sniffer, charset > decoding is a completely separate layer from parsing in XML. I agree with you here. This has the following implication: When using BER or PER, you don't need to understand many different possible character encodings. When using XER, you do, because the encoding is XML 1.0. > The differences between BER, PER, and XER parsing are so > profound as to cause the three parsers to have essentially > nothing in common. > > When using XER, is one constrained to a specific encoding? Yes and no. Encoders must use UTF-8, but there is a requirement for decoders to be "non-validating XML processors", which implies a requirement for understanding both UTF-8 and UTF-16. > > Also, I'm curious about which encoding-rules transformations > one can perform without knowledge of the schema: > > BER to PER? > XER to PER? > BER to XER? > XER to BER? None. You always need the schema. For parsing PER you absolutely need the schema. For *parsing* BER you don't need the schema, but there is very little you can do with it without the schema, especially when "implicit tagging" is used. For parsing XER, you don't *need* the schema. Using ASN.1 with XML is much like using XML Schema - you can use the schema either just for validation purposes or for generating program structures to support data binding. Alessandro Triglia > > -- > I suggest you call for help, John Cowan > or learn the difficult art of mud-breathing. > jcowan@r... > --Great-Souled Sam > http://www.ccil.org/~cowan > > > ----------------------------------------------------------------- > 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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