[lug] Web based streaming updates - how to get started?

[Michael D. Hirsch]

On Wednesday 22 January 2003 03:22 pm, Michael J. Hammel wrote:
> I have a project at work where I need to launch an application via a CGI
> script/program and have that application send multiple "status" updates
> back to the script/program.  I've done a modest amount of web
> programming but nothing that makes the CGI program display data, get
> more data, then display the new data over the place where the last data
> was displayed.  I think this is something akin to Push technology.
> Maybe not.  Java is a possibility but I have no experience with Java.
> I'd prefer either a C based solution if possible, and if not, then
> perhaps Perl.
>
> Is there a C library that will take incoming HTTP requests, allow me to
> parse them (similar to CGI.pm) and then send the results back (probably
> just formatted HTML using printf's if this C program is running as a CGI
> script, I would think).  And how can I get the output to refresh the
> browser with each 'status" update I get from the launched application?

The one time I did this we used the "nph" or "non parsed headers" 
capability.  I don't remember the exact details, but essentially your cgi 
tells the web server not to put any headers on your ourput.  You CGI can 
then keep the connection open for a long time and keep sending new output.

A google search for "nph parsed headers" yielded  lot of stuff.  In a quick 
scan I came up with this: 
http://lists.backhand.org/pipermail/backhand-users/2002-February/000710.html

--Michael