Re: [PHP] Re: about php comet
On Fri, Jun 3, 2011 at 1:50 AM, 李白|字一日 calid...@gmail.com wrote: any idea? 2011/5/25 李白|字一日 calid...@gmail.com hello, I am every interested in comet applications recently, and sadly found php is very weak in this area. i am just wondering if it is possible to write an extension to extend the ability of the php to easy the way to comet applications? if it possible for php to hold the connect from the client when it is in fast cgi mode or apache mod php mode? Comet can use one of several techniques for low-latency data ( http://cometdaily.com/about/), with the long-polling mechanism to simulate the realtime pushing of data from the server being a popular option: http://cometdaily.com/2007/11/15/the-long-polling-technique/ http://en.wikipedia.org/wiki/Comet_(programming) http://en.wikipedia.org/wiki/Comet_(programming)To my understanding, PHP itself can accommodate this quite nicely. Merely start an infinite loop that breaks and returns new data when available. You'll probably have to adjust your web server settings and php.ini configuration to allow reasonably long requests for this particular need. However, when requests do time out, it's not a big deal as the javascript should be set up to reinitiate a new request if that happens, just as it would if the request returned new data and closed, giving the appearance of a continuous stream of pushed data. This all said, if you wanted to write an extension to facilitate long polling, you could, but given the natural latencies for these requests, I'm not sure you'd find a significant benefit. Adam -- Nephtali: A simple, flexible, fast, and security-focused PHP framework http://nephtaliproject.com
Re: [PHP] Re: about php comet
is there an efficient way to hold the requests while loop is an expensive way in most cases. and i don't know how to notify the holding connections if the change need to be notify to the holding requests? writing extension to php is also a very expensive way for me:( 2011/6/3 Adam Richardson simples...@gmail.com On Fri, Jun 3, 2011 at 1:50 AM, 李白|字一日 calid...@gmail.com wrote: any idea? 2011/5/25 李白|字一日 calid...@gmail.com hello, I am every interested in comet applications recently, and sadly found php is very weak in this area. i am just wondering if it is possible to write an extension to extend the ability of the php to easy the way to comet applications? if it possible for php to hold the connect from the client when it is in fast cgi mode or apache mod php mode? Comet can use one of several techniques for low-latency data ( http://cometdaily.com/about/), with the long-polling mechanism to simulate the realtime pushing of data from the server being a popular option: http://cometdaily.com/2007/11/15/the-long-polling-technique/ http://en.wikipedia.org/wiki/Comet_(programming) http://en.wikipedia.org/wiki/Comet_(programming)To my understanding, PHP itself can accommodate this quite nicely. Merely start an infinite loop that breaks and returns new data when available. You'll probably have to adjust your web server settings and php.ini configuration to allow reasonably long requests for this particular need. However, when requests do time out, it's not a big deal as the javascript should be set up to reinitiate a new request if that happens, just as it would if the request returned new data and closed, giving the appearance of a continuous stream of pushed data. This all said, if you wanted to write an extension to facilitate long polling, you could, but given the natural latencies for these requests, I'm not sure you'd find a significant benefit. Adam -- Nephtali: A simple, flexible, fast, and security-focused PHP framework http://nephtaliproject.com
Re: [PHP] Re: about php comet
On Fri, Jun 3, 2011 at 2:20 AM, 李白|字一日 calid...@gmail.com wrote: is there an efficient way to hold the requests while loop is an expensive way in most cases. You can call sleep(number_of_seconds_to_sleep) within the while loop to lower the cost, so to speak. and i don't know how to notify the holding connections if the change need to be notify to the holding requests? Sorry, I'm not sure what you mean here. Let's say you were checking a db table for new rows. When a new row appeared, you'd break out of the loop and return the data to the page with the javascript that initiated the request (maybe you're PHP is returning JSON, XML, or an HTML fragment for the javascript to manipulate.) The javascript would update the page content and then initiate a new long-polling request and wait for new data. writing extension to php is also a very expensive way for me:( I agree with you. That's in part why I suggested that the extension wouldn't be needed or worthwhile in this case and basic PHP would be a reasonable solution. -- Nephtali: A simple, flexible, fast, and security-focused PHP framework http://nephtaliproject.com
Re: [PHP] Re: about php comet
On Fri, Jun 3, 2011 at 3:43 AM, 李白|字一日 calid...@gmail.com wrote: 2011/6/3 Adam Richardson simples...@gmail.com On Fri, Jun 3, 2011 at 2:20 AM, 李白|字一日 calid...@gmail.com wrote: is there an efficient way to hold the requests while loop is an expensive way in most cases. You can call sleep(number_of_seconds_to_sleep) within the while loop to lower the cost, so to speak. yes, an interrupt will be a better way. currently libevent is in beta state, and i don't know if the libevent extension can be used in mod_php to implement comet applications. Oh, I see. Yes, I'm not sure I'd try using that extension yet. and i don't know how to notify the holding connections if the change need to be notify to the holding requests? Sorry, I'm not sure what you mean here. please forgive my poor english, i mean we may have projects need interaction with mulitple users and the state changes of one user should be send to the users involved, like online games chatting rooms. I believe I understand you, now. This could get costly in terms of resources, and I now better understand your interest in the libevent extension. I'd be tempted to write custom C extensions for a web server like nginx, which naturally handles asynchronous IO. And, in this case, you could even make use of fast polling instead of long polling, due to the performance of nginx, such as demonstrated in the this example: http://amix.dk/blog/post/19414 And, don't worry about your English too much. My Chinese stops after ni hao ;) Adam -- Nephtali: A simple, flexible, fast, and security-focused PHP framework http://nephtaliproject.com
Re: [PHP] Re: about php comet
On Fri, Jun 3, 2011 at 7:11 AM, Adam Richardson simples...@gmail.comwrote: On Fri, Jun 3, 2011 at 1:50 AM, 李白|字一日 calid...@gmail.com wrote: any idea? 2011/5/25 李白|字一日 calid...@gmail.com hello, I am every interested in comet applications recently, and sadly found php is very weak in this area. i am just wondering if it is possible to write an extension to extend the ability of the php to easy the way to comet applications? if it possible for php to hold the connect from the client when it is in fast cgi mode or apache mod php mode? Comet can use one of several techniques for low-latency data ( http://cometdaily.com/about/), with the long-polling mechanism to simulate the realtime pushing of data from the server being a popular option: http://cometdaily.com/2007/11/15/the-long-polling-technique/ http://en.wikipedia.org/wiki/Comet_(programming) http://en.wikipedia.org/wiki/Comet_(programming)To my understanding, PHP itself can accommodate this quite nicely. Merely start an infinite loop that breaks and returns new data when available. You'll probably have to adjust your web server settings and php.ini configuration to allow reasonably long requests for this particular need. However, when requests do time out, it's not a big deal as the javascript should be set up to reinitiate a new request if that happens, just as it would if the request returned new data and closed, giving the appearance of a continuous stream of pushed data. This all said, if you wanted to write an extension to facilitate long polling, you could, but given the natural latencies for these requests, I'm not sure you'd find a significant benefit. One word of caution... While PHP can be used to implement long polling, bear in mind that PHP is fairly expensive in terms of resource usage per connection. Unless you're swimming in servers or only expecting a few concurrent connections at any one time, I'd recommend using something that holds multiple connections per process, rather than one process per connection. IMO, web-based PHP is not the right solution to this problem. You could write a select-based comet server in PHP, but it definitely wouldn't be in my top 10 language choices. I've just seen a later email in this thread that mentions that this is a chat-type system. Watch this and have your mind blown... http://vimeo.com/20605470 - at some point he describes how to write a pretty efficient chat server in PHP using ZeroMQ, but the whole thing is worth watching. -Stuart -- Stuart Dallas 3ft9 Ltd http://3ft9.com/
Re: [PHP] Re: about php comet
2011/6/3 Adam Richardson simples...@gmail.com On Fri, Jun 3, 2011 at 3:43 AM, 李白|字一日 calid...@gmail.com wrote: 2011/6/3 Adam Richardson simples...@gmail.com On Fri, Jun 3, 2011 at 2:20 AM, 李白|字一日 calid...@gmail.com wrote: is there an efficient way to hold the requests while loop is an expensive way in most cases. You can call sleep(number_of_seconds_to_sleep) within the while loop to lower the cost, so to speak. yes, an interrupt will be a better way. currently libevent is in beta state, and i don't know if the libevent extension can be used in mod_php to implement comet applications. Oh, I see. Yes, I'm not sure I'd try using that extension yet. and i don't know how to notify the holding connections if the change need to be notify to the holding requests? Sorry, I'm not sure what you mean here. please forgive my poor english, i mean we may have projects need interaction with mulitple users and the state changes of one user should be send to the users involved, like online games chatting rooms. I believe I understand you, now. This could get costly in terms of resources, and I now better understand your interest in the libevent extension. I'd be tempted to write custom C extensions for a web server like nginx, which naturally handles asynchronous IO. And, in this case, you could even make use of fast polling instead of long polling, due to the performance of nginx, such as demonstrated in the this example: http://amix.dk/blog/post/19414 thanks for the advice, but i don't know if it can be integrated into web pages. where in web pages, browsers will stop the requests to different ports even when the url having the save domain name. if i want to host more pages, add more interactions, it would be every difficult. so it would be better to have php solutions to make it easier :) And, don't worry about your English too much. My Chinese stops after ni hao ;) ni hao is a good start:) Adam -- Nephtali: A simple, flexible, fast, and security-focused PHP framework http://nephtaliproject.com
