try {
 
  $http = new Varien_Http_Adapter_Curl();
  $config = array('timeout' => 30); # Or whatever you like!

  ## You attach proxy with your custom implementation like this::
  if ($this->getUseProxy()) {
    $config['proxy'] = $this->getProxyHost(). ':' . $this->getProxyPort();
  }
 
  ## You can add ssl certificate with your custom implementation like this::
  if ($this->getUseCertAuthentication()) {
    $config['ssl_cert'] = $this->getApiCertificate();
  }
  $http->setConfig($config);
 
  ## make a POST call
  $http->write(Zend_Http_Client::POST, $this->getApiUrl(), '1.1', array(), $requestQuery);
 
  ## Get Response
  $response = $http->read();
 
} catch (Exception $e) {
 
  $debugData['http_error'] = array('error' => $e->getMessage(), 'code' => $e->getCode());
  $this->_debug($debugData);
  throw $e;
}
 
# Close Call
$http->close();