Subject: Re: PROPOSAL: CAP Error codes definition and handling

From: Frank Dawson/CAM/Lotus <[email-masked]>
Date: Mon, 24 May 1999 15:31:18 GMT

Patrik:

My concern with not specifying some standardized text is as you just
suggested, that an implementation can "specify any text they want". Suppose
that text was entirely contrary to the intended meaning of the numeric
status code? It would be difficult to argue, unless we specify a
standardized text that describes the intended semantics of the numeric
status code. Hence, we need to specify some "recommended" but standard
text.

I agree with you that an implementation may choose to specify a different,
but semantically equivalent text string. Do you agree?

-- Frank

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From: John Stracke <[email-masked]>
Date: Mon, 24 May 1999 16:00:38 +0000

Frank Dawson/CAM/Lotus wrote:

> status code?

What if it does? It doesn't break interoperability, because the CAP
implementation at the other end doesn't do anything with it.  It doesn't
confuse the user, because the user never sees this text.  It does make it
harder to debug, but for that very reason it's unlikely to happen;
implementors don't want to make more work for themselves.  And, if you're
trying to debug a program that's talking to such an implementation, text that
means the wrong thing is a red flag that the other implementor didn't
understand the status code, which is useful data in itself.

--
/=============================================================\
|John Stracke    | My opinions are my own | S/MIME & HTML OK  |
[email-masked]|============================================|
|Chief Scientist | NT's lack of reliability is only surpassed |
|eCal Corp.      |  by its lack of scalability. -- John Kirch |
\=============================================================/

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From: Patrik Fältström <[email-masked]>
Date: Mon, 24 May 1999 18:56:50 +0200

>that text was entirely contrary to the intended meaning of the numeric

It doesn't matter! The program which reads the codes should _only_ 
read the numeric responses. The text is only a help to the person 
debugging the protocol, installation or whatever.

We do have experience of this kind of behavior from many many 
protocols, and you should not do different in this.

The numeric codes should be defined, that's all. You define the codes 
and when they occur. For example 401-Authentication verification 
problems. The numeric code means that the software (server) which the 
user tried to authenticate to could not verify the password, and 
because of that the server can not let the client access the server. 
That is different from 501 which means that the password was verified 
and wrong. 401 basically means "please try again" (in SMTP the 
starting 4 means temporary failure, while the leading 5 means 
permanent failure). The text message together with the 401 error can 
be exactly what kind of problem the server had, for example "Could 
not contact Oracle backend" or "Could not access Notes Database" or 
"Time is out of bounds so Kerberos authentication failed".

The text should _not_ be defined.

See my point?

    Patrik