Posted by Jerry Stuckle on 06/03/07 15:09

amygdala wrote:
> "Jerry Stuckle" <jstucklex@attglobal.net> schreef in bericht
> news:YrqdnQcjBsSkq__bnZ2dnUVZ_j6dnZ2d@comcast.com...
>> amygdala wrote:
>>> "Alexey Kulentsov" <crimaniak@crimaniak.com> schreef in bericht
>>> news:4661b521$0$90262$14726298@news.sunsite.dk...
>>>> DavidNorep wrote:
>>>>> I do not know PHP, consider to write a CGI with this technology and
>>>>> have the following question.
>>>>>
>>>>> Is it possible to invoke a PHP script and let it endlessly wait for
>>>>> requests from a website (a Java applet in my case) and serve the
>>>>> requests when they arrive? I want to avoid loading the script for each
>>>>> request.
>>>> Yes, but only for output. I done web chat with this technology (I call
>>>> it endless connection) long time ago, before AJAX era. It was PHP script
>>>> on server-side and javascript on client-side. You need set_time_limit()
>>>> to prevent timeout on server so you can't do it in safe mode. And you
>>>> need to send periodically something to prevent timeout on client.
>>>> Request sent to additional short script who put it to database or
>>>> another place. Main script in endless loop checks for new requests,
>>>> process it and sends result back to client.
>>>> Now here is no reasons to do such things.
>>> Correct me if I'm wrong here, but I thought there was some sort of
>>> solution for this, using sockets. Or is this perhaps what you are
>>> refering to already?
>>>
>>> I once ran a very small test with socket connections as a command line
>>> script. My goal was to write a little http chat app. I didn't follow up
>>> on that anymore. But I had the feeling though that this little script
>>> could easily be ported to some webserver environment. Probably not too a
>>> stressful environment, but still.
>>>
>> Good thing you didn't follow up with this though. A socket-attached
>> script is much different than a web-based one.
>>
>>> @ DavidNorep: you mentioned the use of a JAVA applet. I don't know much
>>> about JAVA but I assume JAVA has some socket interfaces itself too, no?
>>> This could rule out client timeouts I think.
>>>
>> Yes, java has socket interfaces. But it doesn't rule out client timeouts.
>>
>>> Also, I vaguely recall the script didn't need to loop, it would just
>>> listened to a socket, and started doing things as soon as it got input on
>>> the socket. I'll have look around to see if I can find the script.
>>>
>>> In the meanwhile do a search for sockets. That should give you some
>>> direction.
>> As I said - socket interfaces are much different that web-based ones. For
>> one thing - sockets typically stay open as long as the chat (or whatever)
>> session is active. Sockets used for HTTP are closed at the end of each
>> page.
>>
>> A BIG difference.
>>
>
> Hmm, I probably didn't express myself good enough then. Or perhaps I'm
> missing essential knowledge here. But the point I was hoping to get accross
> was, that perhaps because JAVA can handle socket connections it wouldn't
> have to be an HTTP socket that the applet connects to. Rather it could
> maintain a statefull connection on some port? Does that make any sense? Or
> am I talking complete rubbish here? Could very well be. ;-) Cause my
> networking knowledge is very poor.
>
>

You made a comment: "My goal was to write a little http chat app."

Is this an http app? If so, the client will get timeouts - it can't be
helped. It's part of the protocol (and built into the browsers), no
matter what port you're running on (and no, http is not restricted to
port 80, although that's the most common one). But in general you'll
want some kind of webserver to help with the connections and processing.

If it's not a http app, you have more control over timeouts, although
they can still occur. But you won't be able to use browsers.

You can set up connections on many ports. But there's a lot more to
handling network connections than just opening a port - especially if
you're going to have multiple people connecting. And that's true in any
language.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

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