I'll throw in one more vote for JSON, having used it on a recent project and had great success with that. The above mentioned readability concern is a non-issue imo, because the Perl JSON module has a built-in 'pretty' parameter that takes care of that: 
my $str = $json->objToJson($obj, {pretty => 1, indent => 4});

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In reply to Re: Which format is best to consume from a webservice? by dmorgo
in thread Which format is best to consume from a webservice? by Anonymous Monk

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