xinetd or any other suggestion

[Jerry Feldman]

On Sunday 10 April 2005 3:28 pm, Anand Rao wrote:
> hi ,
>   I have a text based interactive application that I need to run on a
> port.
>
> I had read some articles regarding the usage  of  xinet or  inetd for
> this purpose .. any Good pointers or  suggestions to start  on this ?
There are a few ways you can do this.
One way is to have the application listening on the port. Depending on its 
design, it could listen, then spawn a child (process or thread).  The ssh, 
http and smtp(mail) daemons are usually set up this way. Other comm 
applications are initiated by xinetd (or inetd) where xinetd listens on 
multiple ports, and initiates the appropriate daemon. 

For the first pass, I would take the first approach. Internally, the 
application would:
1. open a socket using socket(2) system call.
2. bind(2) to that port.
3. listen(2) on that port. When an application tries to connect to that 
port, listen(2) returns 0 on success.
4. Upon successful return, use the accept(2) function to accept the 
connection. Accept returns a non-negative integer on success that becomes 
the file descriptor for subsequent read/write operations. At this point you 
can fork a child process (or thread), while the main process (thread) goes 
back and listens. 

Remember in Unix and Linux, open files are passed to child processes, so the 
listener process could be just a stub. 
-- 
Jerry Feldman <gerald.feldman at hp.com>
Partner Technology Access Center (contractor) (PTAC-MA)
Hewlett-Packard Co.
550 King Street LKG2a-X2
Littleton, Ma. 01460
 (978)506-5243