I know that when I first explored persistent CGI (that is what you are
talking about is it not?) that IBM warned against performance impacts.
No, I wasn't talking about IBM's persistent CGI interface. I should
acknowledge that persistent CGI uses Job-based sessions, which is similar.
But I find persistent CGI inadequate for broadly-scoped projects. Our web
portal submits a Job, then redirects browsers to communicate with that Job.
This type of interface is a lot more flexible. In the portal, you can
defined the allowed period of inactivity (in seconds) for every
application. Users can end their Jobs by clicking on its Exit link.
Developers don't have to code anything to enable "persistence"; They just
set a Y/N flag when they add a new application to the portal.
In regard to the IBM performance warning, I'd need more information about
that concern. Do you know the context? Or the rationale?
All my experience suggest that performance of this type of interface is
much better because functionally-complex applications have a lot of
overhead associated with session management. Session management includes
saving and restoring end-user state, including reopening files and
refreshing cursors.
I would suggest that developers who use Job-based session management tend
to develop more functionally-rich applications than those who write code to
manage state. A lot of programmers on other platforms and language
environments dumb down their web applications, which I attribute at least
partly to their having to write code to manage end-user state.
I suspect that it works fine when used in similar situations to
green-screen i.e. a number of known users. Perhaps not such a good idea for
a customer facing site where the number of users is indeterminate.
We support tens of thousands of concurrent interactive users with Job-based
sessions. And we deploy these applications on servers that require about
1/10th to 1/20th the number of CPU cores that our competitors require, who
are using Java and other language environments that require programmers to
manage session state.
midrange.com
