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                $content_type = $type;
                last;
            }
        }
    }

    $r->headers_out->set( 'Vary'          => 'Accept' );
    $r->headers_out->set( 'Pragma'        => 'no-cache' );
    $r->headers_out->set( 'Expires'       => 'Thu, 01 Jan 1970 00:00:00 GMT' );
    $r->headers_out->set( 'Cache-Control' => 'no-store, no-cache, must-revalidate, post-check=0, pre-check=0' );

    my $callback = $MIMES->{$content_type};
    my $content  = $callback->( @$progress, $r );

    $r->content_type($content_type);
    $r->set_content_length( length $content );
    $r->write($content);

    return Apache2::Const::OK;
}

1;

__END__

=head1 NAME

Apache2::UploadProgress - Track the progress and give realtime feedback of file uploads

=head1 SYNOPSIS

In Apache:

    PerlLoadModule             Apache2::UploadProgress
    PerlPostReadRequestHandler Apache2::UploadProgress

In your HTML form:

 <script src="/UploadProgress/progress.js"></script>
 <link type="text/css" href="/UploadProgress/progress.css"/>
 <form action="/cgi-bin/script.cgi"
       method="post"
       enctype="multipart/form-data"
       onsubmit="return startEmbeddedProgressBar(this)">
 <input type="file" name="file"/>
 <input type="submit" name=".submit"/>
 </form>
 <div id="progress"></div>


=head1 DESCRIPTION

This module allows you to track the progress of a file upload in order
to provide a user with realtime updates on the progress of their file
upload.

The information that is provided by this module is very basic.  It just
includes the total size of the upload, and the current number of bytes that
have been received.  However, this information is sufficient to display lots of
information about the upload to the user.  At it's simplest, you can trigger a
popup window that will automatically refresh until the upload completes.
However, popups can be a problem sometimes, so it is also possible to embed a
progress monitor directly into the page using some JavaScript and AJAX calls.
Examples using both techniques are discussed below in the EXAMPLES section.


=head1 EXAMPLES

=head2 Simple Popup Upload Monitor

The simplest way to add a progress monitor to your forms is to use the popup
technique.  This will launch a popup window with a progress monitor that will
automatically refresh until the upload is complete.  The popup will use the XML
method by default, and format the page using an included XSL stylesheet (which
can be customized to suit your needs).  If the browser does not support XML
transformations, then content negotiation will automatically fall back on a
basic HTML page.

Here is what you need to do to get the popup technique working:

 <script src="/UploadProgress/progress.js"></script>
 <form action="/cgi-bin/script.cgi"
       method="post"
       enctype="multipart/form-data"
       onsubmit="return startPopupProgressBar(this, {width : 500, height : 400})">
 <input type="file" name="file"/>
 <input type="submit" name=".submit"/>
 </form>

So all we have done is add an onsubmit handler on the form that will pop up a
new window and load the progress monitor.  No changes need to be made to your
CGI script, and nothing else needs to be done (apart from the standard Apache
configuration directives listed in the SYNOPSIS above)

=head2 Embedded Upload Monitor

It is also possible to embed the progress monitor directly into the page and it
is just as easy:

 <script src="/UploadProgress/progress.js"></script>
 <link type="text/css" href="/UploadProgress/progress.css"/>
 <form action="/cgi-bin/script.cgi"
       method="post"
       enctype="multipart/form-data"
       onsubmit="return startEmbeddedProgressBar(this)">
 <input type="file" name="file"/>
 <input type="submit" name=".submit"/>
 </form>
 <div id="progress"></div>

The only difference is that we changed the onsubmit handler to call
startEmbeddedProgressBar, and then we added and extra 'div' tag to indicate
where we want the progress monitor to appear.


For complete runable examples please see the scripts in the examples directory.

=head1 APACHE CONFIGURATION

=over 4

=item UploadProgressBaseURI

Change the location of the extra support files, so that you can customize them
to suit your needs.

 UploadProgressBaseURI /CustomUploadProgess
 Alias /CustomUploadProgess /var/www/customprogressfiles

Make sure that you copy all the support files found in the 'extra' directory to
this new location and then you can customize them to your liking.

This currently only affects the urls used in the XML/XSL and HTML mime handlers
used in the popup progress monitor.

=back

=head1 HANDLERS

=over 4

=item handler

This handler should be run at the PerlPostReadRequestHandler stage,
and will detect whether we need to track the upload progress of the current
request.  There are 5 ways for the handler to determine if the upload progress
should be tracked:

=over 4

=item X-Upload-ID

There is an incoming header called X-Upload-ID which contains the progess ID

=item X-Progress-ID

There is an incoming header called X-Progress-ID which contains the progess ID

=item Query contains ID

The query portion of the URL consists of just a 32 character hexadecimal
string (for example http://localhost/upload.cgi?1234567890abcdef1234567890abcdef)

=item Query contains progress_id

There is a query parameter in the query string called progress_id, and it
contains a 32 character hexadecimal number (for example
http://localhost/upload.cgi?progress_id=1234567890abcdef1234567890abcdef)

=item Query contains upload_id

There is a query parameter in the query string called upload_id, and it
contains a 32 character hexadecimal number (for example
http://localhost/upload.cgi?upload_id=1234567890abcdef1234567890abcdef)

=back

Note that you can not pass the progress_id as a hidden POST parameter,
since the Apache2::UploadProgress module never actually decodes the POST
request so it will not be able to determine what the ID is.  The reason
for this is that we are trying to track the rate at which the POST request
takes to upload, so we need that ID before we even start counting the incoming
POST request.  So the ID must be passed as a header, or as a simple query parameter,
as part of the action attribute of the form.

=item progress

When called, this handler will return the upload progress of the request
identified by the given ID.  The ID can be provided in exactly the same way
as in the handler method given above (Although is usually easiest to just provide
is as a query parameter called progress_id).

This handler can return the results in several different formats.  By default,
it will return XML data, but that can be changed by altering the Accept header