Vinod, Interesting...
Okay unless I'm mistaken, what you want to do can't be accomplished through PHP. However, you may want to take a look at libnet. http://www.packetfactory.net/Projects/Libnet/ I've always wanted someone to create a PHP interface for this- unfortunatly my C isn't quite there yet, but I'm working on it... Have fun! On Tuesday 21 May 2002 22:55 pm, Vinod Panicker wrote: > Hi, > > It still seems like I havent made the problem clear enough. > > I am aware of the print(), echo() and flush() functions and what > they do. It does not fit in as a solution. Let me explain my > problem more elaborately - > The client calls a PHP script, script_a.php on the Apache web > server, using a Keep-Alive connection. The script returns some > response to the client which it uses. Now since the connection is > a Keep-alive, apache still has it open for reading and writing. > When the client wants to call other scripts, it just sends the > request over the same connection. Now the thing is that if the > server needs to send some ASYNCHRONOUS data to the client, without > the client requesting for anything, a normal PHP script wont be > able to do it, since the script would get executed by the web > server ONLY on a client request (coz thats the way HTTP works). > Now what i was thinking was - if i could get hold of the socket > that is being used by apache to send data to the client, I could > effectively write() to it, from a C++ app or a PHP script (which > gets invoked from lets say another server). print(), echo() etc > are functions that write to the output stream, which is opened as > a result of the clients request, by the web server. > > I want the ability to write to a socket thats been created earlier > - i want to steal it from Apache, so that i can use it when and > where i like. > > Functions like echo() and print() are not going to work here, i > will have to use write() so that i can specify the socket to which > the data has to be written! > > Hope the problem is understood now. > > Now for your question - > When the client wants to send data to the server, it just has to > open a socket connection with the web server, and issue a GET or a > POST request! if the connection is a keep-alive connection, and > it has already been created, the client just has to do a GET or a > POST without the need to connect(). > > This mechanism, where the client frequently connects() to the > server and checks for messages is called polling. One way of > reducing the high overhead of this is to reuse the connection by > using a keep-alive connection. A still better improvement would > be to remove the need for a poll altogether, by doing something > (thats what my question is all about) on the server so that it can > send data asynchronously to the server. > > > Tx, > Vinod. > > On Wed, 22 May 2002 Bogdan Stancescu wrote : > >For your specific problem, I think Mr. Lemos has provided a > >viable solution (using print() or echo() and flush() whenever you > >need to, instead of grabbing the socket and write() to it). My > >problem however is how you envision solving the communication the > >other way around (i.e. when the CLIENT wants to send data to the > >server). > > > >Bogdan > > > >Vinod Panicker wrote: > >>Hi, > >> > >>Tx for your very prompt reply. > >> > >>Yeah, I'll post the solution as soon as I find it someplace. > >> > >>Let me outline the problem in more detail - > >> > >>Client (VC++) calls a PHP script on the server, specifies the > >>connection type as Keep-Alive. The PHP script, somehow (still a > >>big question) gets the socket on which the apache server has > >>received the client request (so that it can send data to the > >>client later) and stores it in a database. > >> > >>Now whenever another PHP script wants to send data > >>asynchronously to the client, it gets the socket from the > >>database, and just calls a write() on it. Since the connection > >>is still open (Keep-Alive), the client receives the information, > >>and doesnt have to poll the server periodically. > >> > >>The application of this is indeed destined for a messaging > >>product, and could benefit a lot of other areas as well. > >> > >>The only thing that is needed is the socket from apache. > >> > >>Someone somewhere knows how to get this done, i'm sure :) > >> > >>Possibly a hack into the PHP module can get this done, i'm open > >>to suggestions. > >> > >>Tx, > >>Vinod. > >> > >>On Tue, 21 May 2002 Bogdan Stancescu wrote : > >>>Hi! > >>> > >>>I'm looking for an answer to your questions as well, so if you > >>>do find a solution on other lists, could you please post it > >>>here as well? > >>> > >>>Regarding the issue, your proposal wouldn't make for > >>>full-duplex as far as I understand since I don't see how the > >>>client would be able to send any data on the same connection > >>>_after_ getting connected. > >>> > >>>What are you using on the other end of the pipe (on the > >>>client)? Plain HTML? Flash? Java? Something else? > >>> > >>>Bogdan > >>> > >>>Vinod Panicker wrote: > >>>>Hi, > >>>> > >>>>We have developed a client-server application where the server > >>>>needs to send asynchronous data to the client. Now since we > >>>>are using Apache/PHP/MySQL, the client needs to poll the > >>>>server periodically for information. > >>>> > >>>>I was thinking if there was some way to get around this basic > >>>>problem. I understand that this is how things are supposed to > >>>>work, but it would be just great if i could PUSH data from the > >>>>server to the client, using HTTP. > >>>> > >>>>Since HTTP is a request/response based protocol, Apache would > >>>>not send any data to the client asynchronously. So what i was > >>>>thinking was - If i tell the server to allow Keep-Alive > >>>>connections, and increase the timeout value and max requests, > >>>>I would effectively have a constant TCP connection. Now the > >>>>only problem would be of sending asynchronous data to the > >>>>client. Solution? Here goes - If there was some way in which > >>>>i could get hold of the file descriptor(socket) that is being > >>>>used by apache to write data to the client, then i could, from > >>>>a PHP script also send any data to the client using the socket > >>>>functions of PHP since i already have the socket with me. > >>>> > >>>>This would mean that the client doesnt have to poll the server > >>>>for data any more... and if the connection does get closed, > >>>>the client could reconnect to the server asking for another > >>>>keep-alive connection. > >>>> > >>>>Now I know that this is probably the wrong place to put such a > >>>>query - maybe the apache list would have been better. But > >>>>since I'm using PHP out here, i thought i'd give it a try. > >>>> > >>>>Does the solution sound very outlandish? Are there any > >>>>pitfalls? And finally, how do i get hold of the socket? > > > >-- PHP General Mailing List (http://www.php.net/) > >To unsubscribe, visit: http://www.php.net/unsub.php > > _________________________________________________________ > Click below to visit monsterindia.com and review jobs in India or > Abroad > http://monsterindia.rediff.com/jobs -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
