29 Mar
2009
29 Mar
'09
6:29 p.m.
Hi all!
I have a simple question about OSC, or more specifically, the liblo
implementation: Is it possible to broadcast OSC messages to multiple
receiving ends *in different processes*? That is, without needing to
create N 1-1 communication channels, using N ports?
The obvious thing would be to create two servers listening to the same
port (using lo_server_thread_new ). But liblo doesn't allow creating two
servers listening the same port.
Ideas to work-around this?
P
29 Mar
29 Mar
7:38 p.m.
Hi,
Please check out LibLo's multicast support, this is probably what you want.
There is also very limited support for broadcast messages (to
255.255.255.255), but I think (imho) that multicast is a preferred
solution.
In short, with multicast, each server joins a "group" in a specific IP
range (starting with 224), and clients can send messages to this group
for anyone listening.
http://en.wikipedia.org/wiki/IP_Multicast
Steve
On Sun, Mar 29, 2009 at 4:29 PM, Pau Arumí <pau.arumi(a)barcelonamedia.org> wrote:
Hi all!
I have a simple question about OSC, or more specifically, the liblo
implementation: Is it possible to broadcast OSC messages to multiple
receiving ends *in different processes*? That is, without needing to
create N 1-1 communication channels, using N ports?
The obvious thing would be to create two servers listening to the same
port (using lo_server_thread_new ). But liblo doesn't allow creating two
servers listening the same port.
Ideas to work-around this?
P
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8:38 p.m.
El dg 29 de 03 de 2009 a les 17:38 -0400, en/na Stephen Sinclair va
escriure:
Hi,
Please check out LibLo's multicast support, this is probably what you want.
There is also very limited support for broadcast messages (to
255.255.255.255), but I think (imho) that multicast is a preferred
solution.
In short, with multicast, each server joins a "group" in a specific IP
range (starting with 224), and clients can send messages to this group
for anyone listening.
But in my case I have multiple processes in the same computer that
listens the same source (another process also in the same computer). If
I understand well multicast, it does not help in my situation, right?
Thanks,
P
On Sun, Mar 29, 2009 at 4:29 PM, Pau Arumí <pau.arumi(a)barcelonamedia.org> wrote:
> Hi all!
>
> I have a simple question about OSC, or more specifically, the liblo
> implementation: Is it possible to broadcast OSC messages to multiple
> receiving ends *in different processes*? That is, without needing to
> create N 1-1 communication channels, using N ports?
>
> The obvious thing would be to create two servers listening to the same
> port (using lo_server_thread_new ). But liblo doesn't allow creating two
> servers listening the same port.
>
> Ideas to work-around this?
>
> P
>
> _______________________________________________
> Linux-audio-dev mailing list
> Linux-audio-dev(a)lists.linuxaudio.org
> http://lists.linuxaudio.org/mailman/listinfo/linux-audio-dev
>
9:14 p.m.
On Mon, Mar 30, 2009 at 12:38:38AM +0200, Pau Arumí wrote:
But in my case I have multiple processes in the same
computer that
listens the same source (another process also in the same computer). If
I understand well multicast, it does not help in my situation, right?
If your destination processes are just waiting for
commands without creating a permantent connection to
the source of these commands (in other words. they
are UDP receivers) then multicast is the way to go.
Instead of listining on a normal IP address the
receivers should join a multicast group. Liblo
does provide this AFAIK. Such a receiver is still
a 'server', which is somewhat misleading.
When creating a multicast socket you normally need
to provide not only the multicast IP address and
port but also an interface address. Liblo seems
to use INADDR_ANY for this in its multicast receiver,
which is rather strange.
AFAICS liblo does not provide a way to create a multicast
sender. Strangely there is a IP_MULTICAST_TTL option set,
but no I've found no IP_MULTICAST_IF option which would
be required in a sender.
Ciao,
--
FA
Io lo dico sempre: l'Italia è troppo stretta e lunga.
30 Mar
30 Mar
12:05 p.m.
On Sun, Mar 29, 2009 at 7:10 PM, Fons Adriaensen <fons(a)kokkinizita.net> wrote:
On Mon, Mar 30, 2009 at 12:38:38AM +0200, Pau Arumí
wrote:
In particular, the TTL setting on outgoing multicast messages can be
used to make sure the message stays within the local host, if that's
what you intend. So you have pretty good control on how far the
message will go. (Usually one stays within the current subnet.)
But in my case I have multiple processes in the
same computer that
listens the same source (another process also in the same computer). If
I understand well multicast, it does not help in my situation, right?
If your destination processes are just waiting for
commands without creating a permantent connection to
the source of these commands (in other words. they
are UDP receivers) then multicast is the way to go.
Instead of listining on a normal IP address the
receivers should join a multicast group. Liblo
does provide this AFAIK. Such a receiver is still
a 'server', which is somewhat misleading. When creating a multicast socket you normally need
to provide not only the multicast IP address and
port but also an interface address. Liblo seems
to use INADDR_ANY for this in its multicast receiver,
which is rather strange.
AFAICS liblo does not provide a way to create a multicast
sender. Strangely there is a IP_MULTICAST_TTL option set,
but no I've found no IP_MULTICAST_IF option which would
be required in a sender.
I wrote the multicast implementation, but I'm by no means an expert.
I tried to follow the advice here:
http://www.tldp.org/HOWTO/Multicast-HOWTO.html
If you know of something that could be done better, please don't
hesistate to let me know. From what I understood, setting
IP_MULTICAST_TTL and sending to a multicast group IP address is all
that's required to send a multicast message.
"If the host has more than one interface and the IP_MULTICAST_IF
option is not set, multicast transmissions are sent from the default
interface."
Since I don't regularly deal with anything but the default interface,
I never noticed this omission. Thanks for pointing it out.
Can you give some more details on why INADDR_ANY is strange for the
receiver? Looking further at that document..
"Some considerations: first, note that you don't just join a group.
You join a group on a particular network interface."
Is this what you're referring to?
thanks,
Steve
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4 comments
3 participants
participants (3)
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Fons Adriaensen -
Pau Arumí -
Stephen Sinclair