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RRD-CGI-Image-0.01
River stage zero No dependents
++
/ RRD::CGI::Image

NAME

RRD::CGI::Image - accept CGI-style rrdgraph args to build and print image

NOTICE

This is development code - the API may change!

SYNOPSIS

    use RRD::CGI::Image;
        use CGI qw[Vars header];

    my $image = RRD::CGI::Image->new(
                rrd_base  => '/var/rrd',
                error_img => '/var/www/.../path/to/graphing_error.png',
        );

        print header( 'image/png' );
        $image->print_graph( Vars() );

METHODS

new() - create new object to handle your bidding

Behaves like any other new(), really.

The graph will be sent to the location specified by output_file(); STDOUT by default.

In addition to the regular rrdgraph options, you can also add a tz=timezone param which will render the graph in the given timezone.

The key-value pairs need a little translation to get them successfully passed through the URL. Your URL or CGI library will probably handle most of this automatically. Here's the full examplanation.

Let's convert a fairly standard set of args for RRDs::graph() to GET-style CGI params, starting with:

        RRDs::graph(
                '/path/to/output/file.png',
                '--start' => '-1d',
                '--end' => 'now',
                '--height' => 200,
                '--width' => 600,
                '--imgformat' => 'PNG',
                '--lower-limit' => 0,
                '--title' => 'This is a title',
                '--vertical-label' => 'bps',
                'DEF:ds0' => '/var/rrd/router/data/router.example.com/gigabitethernet101.rrd:ds0:MAX',
                'DEF:ds1' => '/var/rrd/router/data/router.example.com/gigabitethernet101.rrd:ds1:MAX',
                'CDEF:in:ds0,8,*',  # convert bytes to bits
                'CDEF:out:ds1,8,*',
                'LINE1:in#33ee33:Input',
                'LINE1:out#0000ff:Output',
        );

First, completely drop the first argument. We don't need an output filename anymore - that's handled by output_file() instead.

Next, change the Perl hash-style key-value params to from key > value to CGI-style: key=value;

Next, delete the first half of the path - the rrd_base() - from your DEF statements. That will change the DEF lines to:

        'DEF:ds0' => 'router.example.com/gigabitethernet101.rrd:ds0:MAX',
        'DEF:ds1' => 'router.example.com/gigabitethernet101.rrd:ds1:MAX',

Finally, make sure your params are encoded so they pass through the CGI interface. URI::Escape::uri_escape() will, for example, convert the hashmarks in LINE1 statements from # to %23. Here's what the LINE1 entries should look like after encoding:

        'LINE1:in%2333ee33:Input',
        'LINE1:out%230000ff:Output',

Many of these will be handled automatically if you're relying on a CGI or URL module to construct the URL for you.

output_file() - where will the new graph be created?

Defaults to STDOUT (-).

rrd_base() - pathname to your RRD files.

Users will be able to specify partial paths to the RRDs beneath this directory in their DEF declarations but they will be sandboxed into this directory. Don't be too permissive - it's a security risk.

Must end with "/".

error_img() - pathname (not URL) to an image that says "an error happened".

Check your webserver's logs to see what went wrong.

tz() - get/set the timezone for the graph.

Pertinent if you have RRDs in different timezones.

normalize_params() - clean up and reassemble the input params

Called internally.

logging() - if true, will print the normalized (processed) params to log

AUTHOR

Joshua Keroes, <joshua at cpan.org>

BUGS

Please report any bugs or feature requests to bug-rrd-cgi-image at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=RRD-CGI-Image. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc RRD::CGI::Image

You can also look for information at:

SEE ALSO

RRDs

COPYRIGHT & LICENSE

Copyright 2008 Joshua Keroes, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.