Re: [PHP] PHP connection to external application

[Per Jessen <per@xxxxxxxxxxxx>]

hce wrote:

> I am not certain if the msg_send / msg_receive in PHP can talk to the
> external C program msg_send  / msg_receive as PHP and external C
> program are in different processes, different memory spaces. 

System V message queues are intended for just that; IPC = Inter Process
Communication. 

> (a) A simple way is if for every PHP request, it opens socket, sends a
> request and gets a response from the C server then closes the socket.
> It should work, but I am not sure:
>    (i) if the open / close socket per request will cause delays and
> performance issues.

They will cause both delays and performance issues.  But whether these
will matter for your use is a different question.  The process you've
describe (open,get,close) is no different to sending an email or
getting a web-page.  People send a lot of email and serve a lot of
webpages without major performance issues :-)

> (ii) What is the maximum number concurrent requests in a PHP web
> application? 

That's up to your webserver - if it's big enough, you can serve a lot of
concurrent requests. 

> Will the maximum socket number  / or port number (up to 2^16) be a
> bottleneck for large number of concurrent requests (hundred 
> and thousands)?

Probably not. 

> (b) If for all PHP requests share only one socket to connect to the
> external C server, I am not sure if the PHP is able to do multiplex
> responses for each request as the PHP is stateless.

"PHP is stateless" ??  PHP is a scripting language, not a protocol. 
Besides, it would take quite a bit of work to make your thousands of
concurrent PHP requests share a single socket. 


/Per Jessen, Zürich


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