Re: Message Server Plug-In (was What About Price vs. Performance)

Jon,

My decision to write a "Message Server Plug-In" was influenced by quotes
like the following:

"CGI programs have always had a reputation of being slow and unable to
scale. The major reason for this is the way they are loaded. CGI programs
get loaded at each invocation in a process separate from the Web server.
This obviously requires a relatively large amount of resource, both in the
Web server and the operating system."

IBM's Gary Mullen-Shultz, from Servlets: The New 5250 Model.

The API for writing an HTTP Server Plug-in is described in the HTTP Server
Programming Guide.  Plug-ins run in the same address space as the HTTP
Server.  They must be designed to support it's multi-threaded architecture.
I wrote a generic plug-in to forward Web requests to RPG programs that are
waiting to receive them.  My plug-in interfaces with another server I call a
"switch" to get requests to the right application, and to balance loads.

Instead of starting more BCI Servers to handle peak loads, the HTTP Server
uses threads that are started from it's main BCH program.  I start multiple
instances of an RPG program if warranted by demand.

I've only done rough performance comparisons between this approach, and CGI.
But in each case, the performance was at least double.  And I've discovered
other benefits associated with running RPG programs as servers.

Hope that helps.

Nathan.



> ------------------------------
>
> Date: Fri, 6 Apr 2001 17:39:23 +0200
> From: Jon.Paris@hal.it
> Subject: Message Server Plug-In (was What About Price vs. Performance)
>
>  >> For the best possible performance, I decided to use a message
interface
> between the HTTP Server, and the ILE application.
>
> I may be slow today, but I still don't understand the basic implementation
> here Nathan.  What program places the message on the Q?  If it is a
> conventional CGI program, then I can't see how that helps any with
> performance relative to simply calling that program "directly" from the
> browser.  In fact it would seem to force you to introduce additional logic
> to start up multiple servers to handle peak loads - something the HTTP
> server jobs will do automatically.
>
> I guess I'm missing something here - but what?
>


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