Subject: Renamed: Backward Compatibility

From: "Frank Dawson" <[email-masked]>
Date: Tue, 23 Mar 1999 09:54:22 -0500

On Monday, March 22, 1999 5:44 PM, Doug Royer wrote, in part:

>If you don't provide the ability for the CUA to set the version,
>it breaks CUA's when the new servers come out.
>
>I had mentioned that it was what I saw as a large bug in IMAP.
>

<snip>

>How would existing CUA's adjust to a new CS?
>
>I can imagine that any one vendor would keep their CS and CUA in sync.
>However it would break interoperability if your ISP upgraded and
>the only way you found out is your 3rd party product broke.
>

<snip>

>And how would the CUA coose to tell the CS that it does not have
>a clue what V1.x is? Whithout the CUA sending a V1.0 as the only
>version supported in a capability command to the CS?

This whole backward compatibility issue can be addressed in a much more
simpler way.

On the CONNECT command in CAP, allow the CUA to specify the version of CAP
services that it wants to connect to. The return code can indicate if that
connection was successful. In addition, the CAPABILITY command can be used
after connection to find out other service levels that the CS supports. This
is a much simpler on the wire exchange than a feeble service negotiation
protocol within the CAP protocol.

- - Frank