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Forum Topic - Few questions on Qnet: (3 Items)
   
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Amit Gourgonda
04/04/2008 9:47 AM
post6462
Few questions on Qnet   
1. Does Qnet support only Connection-Oriented communication?
   - If YES, then how can we implement one process communicate with
multiple other processes through a single port(as in case of UDP)?
   - If Connection-less is also supported then, is the communication a
RELIABLE communication?

2. How a process can be contacted? Is it only through the Name of the
process or is there any port numbers associated with it(as in UDP and
TCP cases)?

3. Is the UDP supported in QNX? Does the UDP use the Qnet as an underlying transport?

Regards,
Amit
Andrew Boyd(deleted)
04/04/2008 9:57 AM
post6463
RE: Few questions on Qnet   
> 1. Does Qnet support only Connection-Oriented communication?

Yup

> If YES, then how can we implement one process communicate with
> multiple other processes

Qnet doesn't do that very well.  Perhaps something like the mqueue
utility?  This might work ok for control messages, but for high
performance data throughput (eg video) you probably want a true
multicast implementation.

> 2. How a process can be contacted? 

See ConnectAttach() function documentation.  It takes a nid/pid/chid
of a server thread as it's args.

> 3. Is the UDP supported in QNX?

Sure, of course!

> Does the UDP use the Qnet as an underlying transport?

Nope.  Qnet and IP are different protocols.  Actually,
I lie like a rug.  Most of the time, that is true, but
it is possible to run qnet on top of IP, but not the
other way 'round

--
aboyd
Amit Gourgonda
04/04/2008 10:13 AM
post6464
Re: RE: Few questions on Qnet   
Thank you Andrew for quick reply,

I think I didnt convey my query properly in the first question.

Actually I want UDP like behavior where in I can just create only one socket in a process and through that I should be 
able to communicate with different processes at probably different times, unlike TCP where one connected socket of a 
process can be used to communicate with only other process with which it is connected.

But your answer to the first question was also informative for me as I wanted to multicasting also.

Thank you and Regards,
Amit

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