Re: [gnet] Multicasting - UDP

[Nelio Pereira <nelio_pereira yahoo com br>]

Hi David.

Let me tell you more about my application. I'm
developing a cluster membership service, i.e, a
service that runs on every node of a cluster to keep
each one of them with the same view of the members of
this cluster.

To send asynchronous messages to group members, I
decided to use multicast messages. I don't know too
much about them, so I don't know exactly what are
their limitations. I had already looked at
recv/recvfrom, but there's no way to read more data
than what my buffer can receive. 

The messages that I exchange among the nodes will be
larger as the cluster grows. That's why I don't want
to be limited on the message size. 

Given this scenario, do you have any sugestion/warning
? I'd appreciate any comments.

Cheers,

Nelio 


 --- "David A. Helder" <dhelder gizmolabs org>
escreveu: > 
> Nelio,
> 
> Use recv() or recvfrom().  It will tell you the
> buffer length, so you
> don't need the \0.
> 
> The buffer should be large enough to fit the largest
> possible packet for
> your application.  Typically you want to keed it
> under ~1500 bytes,
> since that's the maximum packet size for ethernet. 
> If it's above that,
> the packet will be fragmented, which increases the
> chance the whole
> packet will be dropped.
> 
> David
> 
> 
> On Fri, 2003-05-30 at 22:30, Nelio Pereira wrote:
> > I want to send a piece of information over
> multicast,
> > and this information doesn't have a pre-determined
> > size. That is, its length will vary according to
> the
> > the moment. To determine that the buffer is over,
> I'm
> > attaching a '\0' at its end. My question: how can
> I
> > receive this kind of information over UDP sockets?
> If
> > I have a receiver buffer large enough to
> accomodate my
> > message, everything is fine; if my receiver buffer
> is
> > smaller than the information being sent, I cannot
> make
> > two consective reads on the UDP socket to get the
> rest
> > of the message.
> > 
> > Does anyone can help me with this issue?
> 
> 
> 
> -- 
> David Helder - dhelder gizmolabs org -
> http://www.gizmolabs.org/~dhelder
>  

=====
+------------------------------------------------------------------------+
                       http://www.ime.usp.br/~nelio

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