X.400 is a binary format, Internet Mail looks like text
As noted in the ASN.1 arguments,
using text for transferring data has some interesting implications.
Traditional arguments in this debate include:
- The binary format of X.400 makes it easy to include binary
stuff without encoding it for transfer. Transferring binary
data in Internet mail requires stuff like UUencode or Base64.
On the one hand, this grows the data by up to 33%; on the other
hand, encoded stuff like this has a good chance of surviving
the vagaries of mail gateways, where binary data is notably
prone to trigger "interesting" behaviour.
- The text format used in Internet Mail headings makes it
trivially easy to show all present headings, no matter why they
were added or by whom it is defined; in a binary format like
X.400 headings, the most reasonable thing you can do with
heading extensions that you don't understand is hide them.
- When you want to debug a problem with a text oriented protocol
like SMTP, you can often simply telnet to the SMTP port on the
troublesome system and type commands by hand; this is
impossible using X.400. This makes the debugger's life easier,
but also makes faking mail quite a bit easier.
- When something comes in that does not fit in with the specific
syntax, an ASN.1 compiler will usually have to resort to
general messages like "syntax error" (there are examples of
products that return "syntax error" when a timezone value of
+3000 is encountered); a text oriented protocol can
display the unparseable value as text, which can be quite
confusing to a naive user, but at least preserves the information.
Last modified: Wed Jul 19 04:53:25 1995