Dear Monks,

I have a problem with preventing the web clients from caching my scrolling graph and would like to seek your helps. Attached below is a piece of my code. Basically, the code would display a continuous scroll graph. However, the second time I ran the code, the same image is redisplayed on the client screen. If I clicked on refresh, then I would see a new image. I searched the web and the examples I found are similar to this

print "Content-type: image/gif\n\n";
print "Cache-control: no-cache\n";
print "Pragma: no-cache\n";
print "Expires: Mon, 06 May 1996 04:57:00 GMT\n";

[download]

However, when I put this into my code, I got an error about incorrect format in my image and nothing is display on the client window. I had to move the

print "Content-type: image/gif\n\n";

[download]

below the other three lines to get the error message to go away but then I have a caching problem. Any helps would be appreciated. Thanks.

my @data = (  
 \@xlabel,
 \@reads,
 \@writes,
 \@updates
 );
my $graph = GD::Graph::lines->new(400,300);
$graph->set(
   x_label      => 'Average Read/Write/Update',
   y_label      => 'Performance ms',
   title        => 'Performance Monitor',
   y_min_value => 0,
   y_max_value  => $ysp,
   y_tick_number => 5,
   y_label_skip => 'auto',
   x_label_skip => 10,
   box_axis => 0,
) or die $graph->error;
$graph->set_legend( 'Read/Item', 'Write/Item', 'Update/Item');
my $myimage = $graph->plot(\@data);
print "Cache-control: no-cache\n";
print "Pragma: no-cache\n";
print "Expires: Mon, 06 May 1996 04:57:00 GMT\n";
print "Content-type: image/gif\n\n";
print $myimage->gif;
print "\n";
print "\n--magicalboundarystring\n";

[download]

In reply to Preventing Web Client From Caching by Anonymous Monk

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