if ($category === 'All') {
    $request = aws_signed_request($locale, array(
            'Operation' => 'ItemSearch',
            'Keywords' => $keywords,
            'SearchIndex'  => $category,
            'ResponseGroup' => 'VariationSummary, Medium, Reviews, Offers'), $public_key, $private_key, $associate_tag);
 }
else{
    $request = aws_signed_request($locale, array(
            'Operation' => 'ItemSearch',
            'Title' => $keywords,
            'SearchIndex'  => $category,
            'BrowseNode' => $childid,
            'Count' => '20',
            'Sort' => 'salesrank',
            'ItemPage' => '1',
            'ResponseGroup' => 'VariationSummary, Medium, Reviews, Offers'), $public_key, $private_key, $associate_tag);
}