Date: Sun, 18 Jan 1998 18:08:19 -0500
From: "Matthew Wall" <wall(_at_)cyrusoft(_dot_)com>
--On Sun, Jan 18, 1998 11:43 -0800 "Ned Freed"
<Ned(_dot_)Freed(_at_)innosoft(_dot_)com>
wrote:
Generally speaking the mail server has to assume that invalid scripts will
appear from time to time. Suppose the ACAP server doesn't validate
properly?
What then?
As such, good error handling has to be part of the server, and we need to
make sure we specify what that is.
OK, there's several approaches we could take here:
0 : relegate syntax checking to end agents, i.e. the generator, storing
agent, and/or interpreting agent, but not place specific requirements on
error conditions as part of the base specification.
Typos happen; errors have to be handled or there will be compliant
implementations that do arbitrarily stupid things on error.
I think a yes/no is enough, provided the interpreter can give a text
response explaining why. Trying to get a list of all the ways an
interpreter can fail is futile.
My only worry is how and when you communicate these back to the user. If
the ACAP server can't validate the script, when does the error get
returned? If the ACAP server does validate the script, but then a runtime
error happens, what happens?
I think the transporting agent *should* validate the code, but there's no
way to enforce that. The filtering agent has to do validation before
running the code so that syntax errors can be weeded out -- make sure that
the filter and the user agree that the script is at least valid before
trying to run it.
Asking the transport to verify the script is good, but not complete; it's
the server's responsibility because there's no other way to even suggest
that the client will get it right.
--
Tim Showalter
tjs+(_at_)andrew(_dot_)cmu(_dot_)edu