rupesh has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I have a perl executable (kindof like an application) which is running on a remote machine... And people in that place only could control the exe ( like input data, accept choices etc. )
To do all that from my place, i've started to use sockets. Since I'm new to sockets and i've got to do the code in less than a week, i've not experimented with it much.
My client looks like this: 
 $sockclient = new IO::Socket::INET (PeerAddr => $remote_host,
                                  PeerPort => $remote_port,
                                  Proto    => 'tcp',
                                 );
    die "Socket could not be created. Reason: $!\n" unless $sockclient
+;

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And my server like this : 
foreach my $hostvar (@remote_host)
    {
    $sockserver = new IO::Socket::INET (LocalHost => $hostvar,
                                  LocalPort => $remote_port,
                                  Proto     => 'tcp',
                                  Listen    => 5,
                                   Reuse     => 1                     
+        
                                 ) or
    warn "Socket could not be created in $hostvar. Reason: $!" unless 
+$sockserver;
    }
    
    while ($new_sock = $sockserver->accept()) 
    {
        while (defined ($buf = <$new_sock>)) 
        {
      # do something with $buf, and ask confirmation, input #etc. from
+ the client and again come back ... in a  loop.
        }
    }
    close ($sockserver);
}

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Could anybody suggest a reliable approach to this so that :
1. My server is running infinitely,
2. My client is connected to the server, and sends info.
3. My server does something with the data and asks client for more input..
4. 2 and 3 continously until some pre-defined key is pressed.

Thanks...Rupz.

Replies are listed 'Best First'.
Re: Sock-Server and Sock-Client
by AcidHawk (Vicar) on Apr 16, 2003 at 10:18 UTC

    Appologies for the VERY long post. I assume that you are running on a Win32 platform as you talk about an exe. You might have a look at running your server as a Win32 Service (Not for the faint hearted) but Re: Install a perl script as a Win NT/2000/XP service. should give you some ideas, or Re: kill a child / parent process (Service Skeleton) where you can get a kick start for the service stuff.

    As far as the client connecting to the server, the server doing stuff with what it receives and exiting the client when a key is pressed there are many references to this type of thing you just need to scratch around a bit. If you have made the server into a Win32 Service all you have to do to stop the server is to Stop the Service.

    Below is a simple example. I cant remember if I made any changes to the following code and so, have NOT tested it, but it should give to a good start.

    Update:Added Service Installer code.

    Read more... (13 kB)
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Re: Sock-Server and Sock-Client
by castaway (Parson) on Apr 16, 2003 at 11:36 UTC
    Umm, that looks a little confused. Your server only needs to listen to one (local) IP and port, which the clients then connect to, thats the point of it being a server. (Unless I misunderstood what you are trying to do).
    For an example of doing that and looping indefinitely, see Re: Daemons in Perl, and just add:
    $x-add(\*STDIN);

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    and:
    if($handle == \*STDIN) ..

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    in appropriate places to be able to read from the command line and stop the program when a key is pressed.
    And fill in the parse_external_command sub to deal with data from the client.

    C.

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      My first problem is this:
      how do i write back to the client from the server, which is running indefenitely?
      And Yes, the server listens to only one client...
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        You just print to the socket you accepted. It's two-way.. So in your example, that would be:
        print $new_sock "Hallo!\n";

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        I'm not sure what you mean by only listening to one client, I meant one IP/Port pair.

        C.

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Re: Sock-Server and Sock-Client
by rupesh (Hermit) on Apr 16, 2003 at 09:30 UTC
    Update:
    The server code states 
    foreach my $hostvar (@remote_host)
    {
    $sockserver = new IO::Socket::INET (LocalHost => $hostvar,

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    because, the requirement is that the client can be run from anyplace.. so the server listens to many clients present in the array, until a connection is established and then continues...
    Any alternatives regarding this issue also will be great!

    Thanks again!!!
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