Re: Websockets on the IBMi

Kevin

On Jul 11, 2012, at 1:07 PM, "Nathan Andelin" <nandelin@xxxxxxxxx> wrote:

Additionally, you will be limited to the number of forked Apache
processes.

Careful there, aren't we talking about forked Apache threads handling socket I/O? Why not set that limit has high as the number of persistent connections you might want to support simultaneously?

While it is no guarantee, most servers that handle WS will not limit you like that ...

I've never seen any socket server that didn't have a limit on the number of concurrent connections, using some sort of configuration directive.

If you are using the prefork MPM then the maximum number of HTTP connections you can have is limited to the number of processes. This is usually under a hundred, defaulting around 25. You can, of course, bump that as high as you like, but idle Apache processes are not cheap, in terms of memory.

If you are using the prefork MPM, threading does not play into it. The way it works is that Apache opens the server socket and then forks. The the OS round robins new accept() calls onto the child forked processes. Once you have a negotiated TCP connection it is bound to that forked process and is the only one that the process will handle.

instead, connecting to some kind of queue,

An Apache thread can connect to a queue too.

It is possible to have a handler connect to a message queue, or use single process nonblocking IO with event listeners. But I don't know of any MPMs that do that.

I built a setup last week using ActiveMQ, JMS and Stomp over
websockets connecting to PHP over FastCGI. You are able to
send data over WS whenever you like.

Sorry, I don't understand that. Are you saying that a server process initiates I/O with a Web Socket client? I don't think that's possible.

No. The client initiates the connection, but once it's open the communication is bi-directional.

-Nathan.

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