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Thomas B. Passin wrote:
> national standards relating to surface transportation -
> they used asn.1 as a schema language, but now want to
> use xml for the actual messages while sticking with the
> asn.1 for schemas, because the existing versions already used it.
Today, now that we've got an updated X.693 and vendor support
for it, these folk can simply use an E-XER encoder/decoder and they'll
have XML moving in an out of the systems that used to only support
binary encodings. And, they won't have to change any code other than
the one or two lines of code that tell the ASN.1 layer which
encoder/decoder to use. Thus, implementors can produce
encoding-independent implementations that will accept either binary
encodings or XML encodings. This means that both new and old systems
can be supported with the same code base.
If these standards groups are smart, they won't force a
complete switch over to XML. What they should do is agree on the ASN.1
schemas and then allow either XML or PER to be used for interchange.
There is no reason to insist on one or the other. In this way, if
someone ends up having a requirement for binary encodings, they won't
have to go change the standard or produce a non-conforming
implementation.
bob wyman
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