Re: Conventions for Sharing User Agent Profiles

> It may also be useful for vendors to say that their user agent
> emulates, let's say Netscape Navigator 2.0. It would be a win if
> the browser could send this as an additional HTTP header in the
> request, e.g. "UA-Emulates:". This would reduce the size of the
> UA profile database and reduce the hit taken by the first visitor
> with the this ua.

This hasn't worked doing matching on the user-agent. There are two
fundamental problems:

1) It requires a reasonable specification of what a working
   "emulation" is. While MS has released parts of this for MSIE,
   NetScape hasn't released one for NSN. A user-agent profile might
   qualify for this.

2) What part of the WWW mechanism is emulated? Supported MIME types?
   Various HTTP headers? The mapping of HTML META elements to HTTP
   headers? Or just the HTML? People have complained about emulations
   that weren't "good enough" for their purpose because they didn't
   support one or more of the non-HTML features.

If the user-agent profile provides descriptions of all those features
(and there's no reason it shouldn't), then authors can build their own
profile that cover the areas they use. In this case, an "emulates"
facility is worthless, because the document author doesn't know what
profile the client author used.

If NetScape can be talked into releasing an a profile for their
browsers, this problem goes away as well. But until they buy into
this, I suspect such work would be wasted.

	<mike

Received on Saturday, 10 August 1996 12:07:40 UTC