Is there a way to set TCP_NODELAY to Socket.flush(), NetConnection.call() or sendToURL()?

Question

I'm writing a real-time app using a Flex/Flash client and my own server running on Linux.

I'd like to be able to send data from the Flex client in real time (in response to user actions). I've tried the following methods:

• flash.net.NetConnection.call()
• flash.net.sendToURL()
• flash.net.Socket.write() followed by flash.net.Socket.flush()

In each case these calls always wait for the server to send an ACK before they can send data again. In other words, if you do:

var nc:NetConnection;
// Setup code left out
nc.call("foo", someData);
// Some more code left out
nc.call("foo", moreData);

The second nc.call() above won't send data to the server until the ACK for the first call has been recieved. I'd like to be able to send data immediately without waiting for that ACK.

If the round-trip time to the server is long (e.g. 300ms) I can only send data to the server 3 times a second. Ideally I'd like to be able to send data up to 30 times per second, but this is only possible with a RTT of around 30ms at the moment.

It doesn't matter if the server itself gets the data 300ms late - I realise I can't beat the speed of light.

Is there any way to get the Flash Player to send data without waiting for an ACK? In other environments this is done by setting the TCP_NODELAY flag on the socket but it seems I don't have that level of control in Flash/Flex.

Update: I think I may have stumbled on a workaround for this. I think the Flash Player tries to get the host browser to give it a separate TCP connection for each NetConnection object, subject to the connection limit for each browser, e.g. 2 for IE. The connection limit can be got around by using sub-domains (haven't tried this yet) so hopefully it should be possible to get closer to real-time behaviour by using a pool of NetConnections.

Thanks.

Answer 1

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