The HTTP::Request::content() method is described as: "$r->content( $bytes ) ... Note that the content should be a string of bytes.", so what do you expect it to do with an anonymous array containing a list of strings:  $req->content([%post_parameters]);?

You should be using the LWP::UserAgent::post() method: "$ua->post( $url, \%form )".

I have seen that method, but it is not clear on how to add the additional MD5 header I need to add, as well as adding the contents of the file. Would you be able to expand a little on your example to show that?

Completely untested, but my interpretation of the docs suggests it should look something like this:

use LWP::UserAgent;
use HTTP::Request::Common;
use Digest::MD5::File qw(file_md5_hex);
use File::Slurp;

#text file to upload
my $text_file = 'file.txt';

#calulate Content-MD5 Header
my $md5hash = file_md5_hex($text_file);

#read file
my $file_contents = read_file($text_file);

#fields to post
my %post_parameters = (
    'a' => 'red',
    'b' => 'blue',
    'c' => 'green'
);

$ua = LWP::UserAgent->new();
$ua->agent('Blah/Perl');
$ua->post( 'http://amazonmws.blah', 
    Content_Type =>'form-data',
    Content-MD5  => $md5hash,
    Content      => [
        file => [ $file_contents, $text_file ],
        %post_parameters 
    ],
);

print STDERR $rsp->status_line;
[download]

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

I've never used the MWS but after a quick skim of the dev guide I think your reading of the spec is incorrect(?). This snippet from their docs seems to line-up with the AWS/APA/BlahBlah.vπ interface neatly–

SignatureMethod—The HMAC hash algorithm you are using to calculate your signature, either HmacSHA256 or HmacSHA1

Good news is you should be able to pull some code from or reuse URI::Amazon::APA. Bad news, you need to read the spec again. Might ask around the forums if one of the CPAN modules (none of which seems to contain "MWS") works for this.

Actually the MD5 hash is one part that is working here. I think the problem is in the LWP syntax with adding the parameters hash and the the file contents. Doesn't like both of those there. I just can seem to find any examples of how to add parameters and the file contents to a post.