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Top Forums Programming Write the source code for messenger Post 302094196 by nathan on Thursday 26th of October 2006 12:25:31 AM
Old 10-26-2006
I'm actually trying to do the same thing (write a simple instant messenger program) but am running into a few problems.

Right now I am just focusing on the "communication" portion, using a command-line interface. I plan to add the GUI stuff later.

I am using C++ and the sockets api and have taken the approach of building both a "Server" and "Client" class. I have designed my instant messaging application to have both the server and client in one executable program.

So, in my main() function, I will:
1) Create an instance of Server ( for example, "Server my_serv( ); " )
2) Create an instance of Client ( for example, "Client my_cli( ); " )
3) Start the server ( for example, my_serv.start() )
4) Client stuff... ( connect to remote computer, enter text data to send, etc ).

One problem I have run into with this approach:

I attempt to start the server then use the client functionality, but then my program hangs, because the socket program is listening for a connection. ( I've tried non-blocking IO with the fcntl call below ).
This bit just gets all current flags for the file descriptor sd1, then adds the O_NONBLOCK flag to it.
Code:
  rc |= fcntl( sd1 , F_SETFL , ((fcntl( sd1 , F_GETFL ))|O_NONBLOCK) );

I believe I might need to use the select() function, but I'm not sure if I'm headed down the wrong path.

Would it be best to split this up into 2 programs ( i.e. one as a server and the other as a client )? Or could (should?) I use fork(), start the server in one process, then the client in the other? (I've tried the fork()ing approach, but had some problems.)

I'm trying to get an idea of how the program would be best designed. Any ideas are appreciated.
 

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Wx::Socket(3pm) 					User Contributed Perl Documentation					   Wx::Socket(3pm)

NAME
Wx::Socket - wxSocket* classes USAGE
use Wx qw(:socket) ; use Wx::Event qw(EVT_SOCKET_INPUT EVT_SOCKET_LOST) ; use Wx::Event qw(EVT_SOCKET_CONNECTION) ; ########## # CLIENT # ########## my $sock = Wx::SocketClient->new(wxSOCKET_WAITALL); EVT_SOCKET_INPUT($parent , $sock , &onInput ) ; EVT_SOCKET_LOST($parent , $sock , &onClose ) ; $sock->Connect('localhost',5050) ; if (! $sock->IsConnected ) { print "ERROR " ;} sub onInput { my ( $sock , $this , $evt ) = @_ ; my $length = 123; my $buffer ; $sock->Read($buffer , 1024 , $length ) ; } ########## # SERVER # ########## my $sock = Wx::SocketServer->new('localhost',5050,wxSOCKET_WAITALL); EVT_SOCKET_CONNECTION($parent , $sock , &onConnect ) ; if ( !$sock->Ok ) { print "ERROR " ;} sub onConnect { my ( $sock , $this , $evt ) = @_ ; my $client = $sock->Accept(0) ; my ($local_host,$local_port) = $client->GetLocal ; my ($peer_host,$peer_port) = $client->GetPeer ; $client->Write("This is a data test! ") ; ... or ... $client->Write( $data , length($data) ) ; $client->Close ; } METHODS
All the methods work as in wxWidgets (see the documentation). The functions for reading data (Read, ReadMsg, Peek) take 3 arguments, like the Perl read() function: ## To read the data into the variable $sock->Read($buffer , 1024) ; ... or ... ## To append data at the given offset: $sock->Read($buffer , 1024 , $offset ) ; The write functions (Write, WriteMsg, Unread) can be used with 1 or 2 arguments: $client->Write("This is a data test! ") ; $client->Write($data , $length) ; EVENTS
The events are: EVT_SOCKET EVT_SOCKET_ALL EVT_SOCKET_INPUT EVT_SOCKET_OUTPUT EVT_SOCKET_CONNECTION EVT_SOCKET_LOST The EVT_SOCKET works as in wxWidgets, the others are wxPerl extensions. Note that EVT_SOCKET events of wxSocketClient and wxSocketServer work differently than other event types. First you need to set the event handler: $sock->SetEventHandler($handler, $id) ; Then you set what types of event you want to receive: ## this select all. $sock->SetNotify(wxSOCKET_INPUT_FLAG|wxSOCKET_OUTPUT_FLAG| wxSOCKET_CONNECTION_FLAG|wxSOCKET_LOST_FLAG) ; Enable the event notification: $sock->Notify(1) ; And only after this use: ## note that $handler must be the same that was used in ## SetEventHandler EVT_SOCKET($handler, $id , sub{...} ) To make the events easier to use, all the proccess is automatic, and you just use: EVT_SOCKET_INPUT($handler , $socket , sub{...} ) EVT_SOCKET_OUTPUT($handler , $socket , sub{...} ) EVT_SOCKET_CONNECTION($handler , $socket , sub{...} ) EVT_SOCKET_LOST($handler , $socket , sub{...} ) ## This is for the events not used yet by the above: EVT_SOCKET_ALL($parent , $socket , sub{...} ) ** The new way is better to handle more than one socket in the same time too. Take a look in the demos. SEE ALSO
Wx, The wxWxwindows documentation at <http://www.wxwindows.org/> AUTHOR
Graciliano M. P. <gm@virtuasites.com.br> COPYRIGHT
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2007-06-18 Wx::Socket(3pm)
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