Message-Id: <199602011453.IAA03079@library.wustl.edu> Date: Thu, 1 Feb 1996 09:40:58 -0500 From: Kevin Thomas <mailto:kevint@OVID.COM> Subject: Re: Search History To: Multiple recipients of list WEBCAT-L <mailto:WEBCAT-L@WUVMD.WUSTL.EDU>
On Wed, 31 Jan 1996, Michael Carroll wrote:> REPLY TO 01/31/96 08:34 FROM mailto:WEBCAT-L@WUVMD.WUSTL.EDU "WEBCAT-L LIST": Search
> History
>
> This is an instance of the more general problem, that the HTTP
> protocol is stateless, while Z39.50 is "stateful". Some
> implementations attempt to solve this problem by passing a session
> id to the Web client, which is then passed back to the Web server.
> This is not without its problems; for example, the session id must
> expire at some point in time, perhaps earlier than the user wants.
The same is true of almost all on-line service providers of almost every kind -- if you sit and stare at the screen for more than a certain amount of time (or go to lunch), the system will log you off. The only difference is that in the WWW case, the user is not given a message saying "I'm going to time you out in 1 minute unless you hit ENTER".
Enjoy, Kevin Thomas