getRate example

 else {
            $currency = $this->getShortName($currency, $this->getLocale());
        }

        $rate = 1;
        if ($currency !== $this->getShortName()) {
            $service = $this->getService();
            if (!($service instanceof Zend_Currency_CurrencyInterface)) {
                throw new Zend_Currency_Exception('No exchange service applied');
            }

            $rate = $service->getRate($currency, $this->getShortName());
        }

        $value *= $rate;
        return $value;
    }

    /** * Returns the set service class * * @return Zend_Currency_CurrencyInterface */