Getting an XML-RPC array with Frontier::Client

[jaldhar]

i'm using Frontier::Client to get back information from Advogato's XML-RPC interface and I'm having trouble with the methods that return an array. Here is a sample invocation of the test.guess method:

---- request ----
<?xml version="1.0"?>
<methodCall>
<methodName>test.guess</methodName>
<params>
</params>
</methodCall>
---- response ----
<?xml version="1.0"?>
<methodResponse>
  <params>
    <param>
      <array>
        <data>
          <value>
            <string>You guessed</string>
          </value>
          <value>
            <int>42</int>
          </value>
        </data>
      </array>
    </param>
  </params>
</methodResponse>

I try to access it from perl like this:

my $client = Frontier::Client->new(
  'url' => 'http://www.advogato.org/XMLRPC', use_objects => 1, 
  debug => 1,);
my ($string, $int) = $client->call('test.guess') or die "$!\n";

and get back the XML above plus:

wanted `value' or `name' tag, got `array' at line 5 column 6

and the variables don't get filled in. Is this a limitation in the module or did I do something wrong?

--
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[tall_man]

It seems the Frontier::Client only expects to return simple values, not arrays. You'll have to go down to the Frontier::RPC2 level and do "decode" calls for yourself. Here's an example:

sub doCommand {
   # Decode the results of the raw command from XML.
   my ($uri, $coder, @rest) = @_;
   my $encoded = doRawCommand($uri, $coder, @rest);
   return $encoded if ($encoded eq "");
   my $result;

   # Decode XML RPC wrapper case.
   my $decoded = $coder->decode($encoded);
   # Note: the result is an array ref with params inside
   $result = $decoded->{value}[0];

   return $result;
}

Update: I should explain that doRawCommand is a routine I wrote to encode and make an XML-RPC request, and that $coder is an instance of Frontier::RPC2.

Update2: One thing about your original code is that Frontier::Client::call will never return an array of values, even if the decoding had worked. It should be able to do an array reference, though.

Update3: I just tried an encoding example, trying to match what Advogato returns:

use strict;
use Frontier::RPC2;
my $coder = Frontier::RPC2->new(use_objects => 1);
my $result = [ "you guessed", 42 ];
my $xml_string = $coder->encode_response($result);
print $xml_string,"\n";

This is the result I got:

<?xml version="1.0"?>
<methodResponse>
<params>
<param><value><array><data>
<value><string>you guessed</string></value><value><i4>42</i4></value><
+/data></array></value>
</param>
</params>
</methodResponse>

The difference is a "value" tag around the "array" level. I believe that is what is throwing off your decode. Advogato must be using a different version of the encoding scheme.

I would suggest asking their support board. If they can't help, you could use a wrapper like my subroutine above and munge the return value to the right syntax before decoding it.

[jaldhar]

Update: nicer error-handling code, correction of syntax errors.

Sorry I got sidetracked by other things (or rather I got retracked from this side track :-) but I returned to this subject and your advice was invaluable.

In the end though I used RPC::XML which is just as easy to use and apparently more complete. Here is what my example code would look like with this module:

use RPC::XML::Client;

my $client = RPC::XML::Client->new('http://www.advogato.org/XMLRPC');
my $result = $client->send_request('test.guess');
die $result unless defined($result);
die $result->code . ': ' . $result->string if $result->is_fault;
print join(' ',  @{$result->value}), "\n";

--
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[Anonymous Monk]

Dude, I found a real cool solution.. Just pass the array elements like below $result1 = $server->call('method1',reasonsArray =>"reason1","reason2","reason3") Thanks, Sarat

[Anonymous Monk]

you have to keep all your array elemement in square braces. in the above comment square braces were removed by this site tagging process