ecs.amazonaws.com Api我们遇到了内部错误

Question

我最近遇到了amazon lookupitem搜索API的问题。以前工作在一个脚本中我已经成功执行了数百个请求，但现在我不知道是什么问题这是我的Amazon.php

class Amazon
{
    // public key
    var $publicKey = "[public key]";
    // private key
    var $privateKey = "[private key]";
    // affiliate tag
    var $affiliateTag = 'affiliateTag';

    /**
     * @param $param
     * @return mixed
     */

    public function generateSignature($param)
    {
        // url basics
        $signature['method'] = 'GET';
        $signature['host'] = 'ecs.amazonaws.' . $param['region'];
        $signature['uri'] = '/onca/xml';

        // necessary parameters
        $param['Service'] = "AWSECommerceService";
        $param['AWSAccessKeyId'] = $this->publicKey;
        $param['Timestamp'] = gmdate("Y-m-d\TH:i:s\Z");
        $param['Version'] = '2009-10-01';
        ksort($param);
        foreach ($param as $key => $value) {
            $key = str_replace("%7E", "~", rawurlencode($key));
            $value = str_replace("%7E", "~", rawurlencode($value));
            $queryParamsUrl[] = $key . "=" . $value;
        }
        // glue all the  "params=value"'s with an ampersand
        $signature['queryUrl'] = implode("&", $queryParamsUrl);

        // we'll use this string to make the signature
        $StringToSign = $signature['method'] . "\n" . $signature['host'] . "\n" . $signature['uri'] . "\n" . $signature['queryUrl'];
        // make signature
        $signature['string'] = str_replace("%7E", "~",
            rawurlencode(
                base64_encode(
                    hash_hmac("sha256", $StringToSign, $this->privateKey, True
                    )
                )
            )
        );
        return $signature;
    }

    /**
     * @param $params
     * @return string
     *
     */
    public function getSignedUrl($params)
    {
        $signature = $this->generateSignature($params);

        return $signedUrl = "http://" . $signature['host'] . $signature['uri'] . '?' . $signature['queryUrl'] . '&Signature=' . $signature['string'];
    }
}

这里是我称之为回复的地方

  

错误500我们遇到了内部错误。请再试一次。'

$Amazon = new Amazon();

$parameters = array(
    "region" => "com",
    "AssociateTag" => 'affiliateTag',
    'ResponseGroup' => 'Medium',
    "Operation" => "ItemLookup",
    "SearchIndex" => "Books",
    "IdType" => "ISBN",
    "ItemId" => $isbn,
);

$queryUrl = $Amazon->getSignedUrl($parameters);

$response = simplexml_load_file($queryUrl);