in reply to Re^2: Handling asynchronous events with Perl
in thread Handling asynchronous events with Perl

I would use Tk. You can read "perldoc Tk" then "perldoc Tk::UserGuide". You can ask questions here, google for sample code at groups.google.com, and ask questions in the friendly newsgroup, comp.lang.perl.tk

I was thinking about your problem, and thought how nice it would be to actually make each AUV an object, then just make a big Tk canvas, put an gridded ocean map on it, and have little icons for each AUV object. You could have a little red indicator to blink when they are surfaced, and when submerged, plot their approximate position based on last readings, etc. You could work out a "coordinate translation" between GPS coordinates and your "gridded-ocean map". It sounds like a doable and fun project.

Of course, as always, the devil is in the details, like error handling, restarting crashed servers, etc. You will probably need to store your AUV object data in a simple database, with backup, in case your monitoring computer crashes and needs to be rebuilt and restarted.

I have posted a few examples which may "stimulate" ideas for you. Like this is a possible way to setup grid patterns -> Tk ImageMap-color-zones.

And here is a nice little intro to how to make independent objects and display them on the screen. I call them bubbles. Anyways, don't get confused by the all the effects. My main purpose was to find a way to make alot of objects, and reuse them so as not ot get memory increases in a long running program. I also used Zinc, because it makes rotations and translations alot easier than the plain Canvas. But this could all be done on a plain Tk::Canvas.....you don't need fancy rotations, just translations, and the plain Canvas does them just fine. Also the package bubble, could be put into it's own .pm, I just make this monolithic for ease of testing the script. This is mostly to show how to make objects which "update their own display". So............ 

#!/usr/bin/perl
use Tk;
use Tk::Zinc;
#use MeM; 

# there is a penalty for creating objects, a slight overhead 
# so if you are going to create alot of objects, you must 
# reuse them....this reconfigures and reuses the bubble objects 

my $mw = MainWindow->new;
$mw->geometry("700x600");
$mw->resizable(0,0);

my $launcher;
my $zinc = $mw->Zinc(-width => 700, -height => 565,
                    -backcolor => 'black',
                    -borderwidth => 3, -relief => 'sunken')->pack();

#my $zwidth  = $zinc->reqwidth; 
#my $zheight = $zinc->reqheight; 
#print "$zheight $zwidth\n";     

# Then we create a filled rectangle, in which we will display explain 
+text. 
$zinc->add('rectangle', 1 , [200, 400, 490, 490],
           -linewidth => 2,
           -filled => 1,
           -fillcolor => 'SkyBlue',
           -priority => 1,
           );

my $text = $zinc->add('text', 1,
                      -position => [350, 445],
                      -anchor => 'center',
                      -priority => 3,
                      -width => 200,
                      );

#####setup 100 bubble objects for reuse############################# 
my %bubs;       #reusable object space 
my @bubjects = (1..100);
my @x = (1,-2,3,-4,5, -1,2,-3,4,-5 ); #give random diagonal motion 
my $count = 0;

foreach my $bub (@bubjects){
     $count++;
     $tag = $count;
     push (@x,shift(@x));
     $afterdelay = 1 + int(rand(99));

# Create the 100 ztkbubble object (see Package ztkbubble below) 
 $bubs{$bub} = ZtkBubble->new(
                 -widget => $zinc,
                 -name => $count,
                 -bub => $bub,
                 -tags => $tag,
                 -x => rand 700,
                 -y => 700,
                 -radius => 10 + rand(30),
                 -color => 'green',
                 -dx => $x[0],
                 -dy => -20,
                 -afterdelay => $afterdelay,
                );
}
########################################################### 

# Display comment 
&comment("Strike any key to begin");

# Create Tk binding 
$mw->Tk::bind('<Key>', \&openmode);

my $closebutton = $mw->Button(-text => 'Exit',
    -command => sub{
                 if(defined $launcher){$launcher->cancel};
                exit(0);
                })->pack;

MainLoop;
##################################################### 
sub openmode {
    $mw->Tk::bind('<Key>', \&closemode);
     &comment("Bubbling!!");


# 50 is about my max on a 800 Mhz K6, adjust accordingly 
$launcher = $mw->repeat(100,sub{
         my $bub = shift @bubjects;
        $bubs{$bub}->bubble_move();
   });
}


sub closemode {
    # and then inform user 
    &comment("We are bubbling baby !!");
}

# Just display comment  
sub comment {
    my $string = shift;
    $zinc->itemconfigure($text, -text => $string);
}

#=====================================================================
+======== 
#                 Bubble  Class 
#=====================================================================
+======== 
package ZtkBubble;

use strict 'vars';
use Carp;
#==================== 
# Object constructor 
#==================== 
sub new {
    my ($class, %arg) = @_;

    # object attributes 
    my $self = {
        'widget' => $arg{-widget},      # widget reference into which 
+it goes 
        'name'  => $arg{-name},         #identifying name  
        'bub'  => $arg{-bub},           #which reusable bubble space i
+t's using 
        'tags' => $arg{-tags},            # tag object of self 
        'x' => $arg{-x},
        'y' => $arg{-y},               # origin coordinates 
        'radius' => $arg{-radius},      # radius 
        'color' => $arg{-color},        # top Group item 
        'dx' => $arg{-dx},              # initial x direction  
        'dy' => $arg{-dy},              # initial y direction  
        'afterdelay' => $arg{-afterdelay},       # repeater time delay
+ 
    };
    bless $self;

#   print "just blessed $self\n"; 

    $self->{topgroup} = $self->{widget}->add('group', 1,
                                       -priority => 2,
                                       -visible => 1);

    $self->{widget}->coords($self->{topgroup}, [$self->{x},$self->{y}]
+);
    $self->{timer}; #declare variable to store internal timer  
    $self->{'init'} = $self->{widget}->tget( $self->{topgroup}  );
    # print join ' ',@{ $self->{init}  },"\n";  #initial position 

   my $color1 = '#';
   for (0 .. 2){
     my $rgb = unpack('H*', pack('n', (int(rand(192)+64))));
     $rgb =~ s/.+(\w\w)$/$1/;
     $color1 .= $rgb;
}

#add items to self group 
    $self->{arc1} =
    $self->{widget}->add('arc',  $self->{topgroup},
                     [-$self->{radius}, -$self->{radius}, $self->{radi
+us}, $self->{radius}],
                     -visible => 1,
                     -filled => 1,
                     -closed => 1,
                     -extent => 360,
                     -pieslice => 1,
                     -fillcolor => $color1,
                     -linewidth => 1,
                     -startangle => 0 ,
                     -tags => [$self->{tags},'bubble'],
                     );
  $self->{arc2} =
  $self->{widget}->add('arc',  $self->{topgroup},
                     [-$self->{radius}/2, -$self->{radius}/2, $self->{
+radius}/2, $self->{radius}/2],
                     -visible => 1,
                     -filled => 1,
                     -closed => 1,
                     -extent => 360,
                     -pieslice => 1,
                     -fillcolor => $self->{color},
                     -linewidth => 1,
                     -startangle => 0 ,
                     -tags => [$self,'bubble'],
                     );

    # Create the Text item representing the jackpot. 
    $self->{txt} =
    $self->{widget}->add('text', $self->{topgroup},
                 -position => [0, 0],
                 -anchor => 'center',
                 -text => $self->{'name'},
                 );

    $self->{line} =
    $self->{widget}->add('curve',  $self->{topgroup},
                     [-$self->{radius}, -$self->{radius},$self->{radiu
+s}, $self->{radius}],
                     -visible => 1,
                     -linecolor => 'white',
                     -linewidth => 3,
                     -tags => [$self,'bubble'],
                     );
    return $self;
}
############################################# 
sub DESTROY{
  my ($self) = @_;
    print "destroying->",$self,' ', $self->{bub}. "\n";
}
########################################### 
#================ 
# Public methods 
#================ 

# Start motion of $self  
sub bubble_move {
    my $self = shift;
$self->_move();
}

#================= 
# Private methods 
#================= 

sub _close {
    my ($self) = @_;
    my $widget = $self->{widget};
    my $group = $self->{topgroup};
    my $name = $self->{name};
    my $bub = $self->{bub};
    my $tag = $self->{tags};

    &main::comment("Poof!!   name->$name    bub#->$bub");
    $widget->dtag($tag);
    $self->{timer}->cancel;
    push @bubjects, $self->{bub};  #return to pool 
#   $self->DESTROY;    #don't use this, since we are reusing them 
}
# Generate motion and  rotation animation. 
sub _move {
    my ($self) = @_;
    my $widget = $self->{widget};
    my $group = $self->{topgroup};
    $widget->translate($group, $self->{'dx'} ,$self->{'dy'});

   $self->{x} += $self->{'dx'};
   $self->{y} += $self->{'dy'};

 #check for side collisions 
   if( ( $self->{x} < 0) or ($self->{x} > $self->{widget}->reqwidth ) 
+)
       { $self->{'dx'} *= -2 }


 #reset bubbles for next run with new name 
 if($self->{y} < -$self->{radius}){
             $self->_close();

             $self->{widget}->tset( $self->{topgroup} , @{ $self->{ini
+t} } );
             # print join ' ',@{ $self->{init}  },"\n"; 
             $self->{x} = ${ $self->{init} }[4];
             $self->{y} = ${ $self->{init} }[5];
             # $self->{widget}->coords($self->{topgroup}, [$self->{x},
+$self->{y}]); 
             $self->{name} = $count++;
             $self->{widget}->itemconfigure($self->{txt}, -text => $se
+lf->{'name'} );
             return }

 $widget->rotate($group,.9,$self->{x},$self->{y} );

#use $self->timer instead of anonymous timer, in order to cancel on cl
+ose  
$self->{timer} = $widget->after($self->{afterdelay}, sub { $self->_mov
+e() });
}

1;

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I'm not really a human, but I play one on earth. flash japh

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