http://qs1969.pair.com?node_id=183730


in reply to Inter-Process Communication

Win32::Pipe will let you establish a bidirectional named pipe. I guess the question becomes: can you establish a named pipe in server context with your win32 app? If so, then your win32 app sets up a pipe as a server, and your Perl script calls

if( $Pipe = new Win32::Pipe( $PipeName ) ) {
    # talk...
}
else {
    # continue polling. The client's call failed.
}

[download]

That way your win32 app is blocking, but your Perl app isn't.


Replies are listed 'Best First'.
Re: Re: Inter-Process Communication
by Nitrox (Chaplain) on Jul 21, 2002 at 03:08 UTC
    Unfortunately the win32 app is a Home Automation engine that currently doesn't execute its scripts in a separate thread, so I can't put it in a blocked state either.

    -Nitrox

[reply]

      OK, some other ideas:

      Set up some shared memory. Most of the CPAN stuff is SYSV based, but perhaps use Cache::Cache.

      Or perhaps have your Win32 app write the data to a normal file, and then send a signal to the perl process. Put a signal handler in the script so that it knows when it is time to read the file.


[reply]
        Thanks for the tip perigeeV I think I found my solution, albeit not as elegant as I had hoped.

        I couldn't use the shared memory function because IPC::ShareLite won't compile on Win32 and is required. But Cache::Cache will still compile with it.

        So my solution is to use Cache::FileCache. I've include two quick proof of concept scripts to demonstrate:

        First run the 'writer': 

        # Program 1
use Cache::FileCache;

my $cache = new Cache::FileCache({ 'namespace' => 'SharedCache', 'defa
+ult_expires_in' => 600 } );

my $passed_data = "This is a passed string";

$cache->set( "Data", $passed_data, "10 minutes" );

        [download]
        Then run the 'reader': 
        #Program 2
use Cache::FileCache;

my $cache = new Cache::FileCache( { 'namespace' => 'SharedCache', 'def
+ault_expires_in' => 600 } );

my $passed_data = $cache->get("Data");

print "$passed_data\n";

        [download]
        Looks like a winner, and only after about 18hrs of banging my head against the pile of soda cans on my desk!

        -Nitrox

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom