Call method

Common request parameters specify the request parameters that must be used by every interface.

Name	Type	Required	Description
Format	String	No	Type of value returned, JSON and  XML supported. The default value is XML.
Version	String	Yes	The API version, with the date format:YYYY-MMDD. The current version is 2014-11- 11.
AccessKeyId	String	Yes	The secret key ID used to access services, issued to a user by Alibaba Cloud.
Signature	String	Yes	The signature result string. See the description of the signature mechanism for details on the signature calculation method.
SignatureMethod	String	Yes	The signature method, HMACSHA1 currently supported.
Timestamp	String	Yes	The request’s timestamp. The date format follows the ISO8601 standard and uses UTC time. Format: YYYY-MM-DDThh:mm:ssZ. E.g.: 2014-11-11T12:00:00Z (Equivalent to 11/11/2014 20:00:00 Beijing time)
SignatureVersion	String	Yes	Signature algorithm version. The current  version is 1.0.
SignatureNonce	String	Yes	A unique random number, used to prevent replay attacks. The user must use different random numbers for different requests.

Request example:

https://cdn.aliyuncs.com/?Format=xml&Version=2013-01-10&Signature=Pc5WB8gokVn0xfeu%2FZV%2BiNM1dgI%3D&SignatureMethod=HMAC-SHA1&SignatureNonce=15215528852396&SignatureVersion=1.0&AccessKeyId=key-test&Timestamp=2012-06-01T12:00:00Z

Example of XML results returned:

<? xml version="1.0" encoding="UTF-8"? > 
<!—Result Root Node-->
<Interface Name+Response>
    <!—Return Request Tag-->
    <RequestId>4C467B38-3910-447D-87BC-AC049166F216</RequestId>
    <!—Return Result Data-->
</Interface Name+Response>

Example of XML results returned:

{
"RequestId": "4C467B38-3910-447D-87BC-AC049166F216",
/* Return Result Data */
}

Example of XML results returned: (XML results returned include a message stating if the request was successful and the specific service data.)

<? xml version="1.0" encoding="UTF-8"? > 
<!—Result Root Node-->
<API name+Response>
    <!—Return Request Tag-->
    <RequestId>4C467B38-3910-447D-87BC-AC049166F216</RequestId>
    <!—Return Result Data-->
</Interface name+Response>

JSON example:

{
    "RequestId": "4C467B38-3910-447D-87BC-AC049166F216",
    /* Return result data */
}

XML example:

<? xml version="1.0" encoding="UTF-8"? >
<Error>
<RequestId>8906582E-6722-409A-A6C4-0E7863B733A5</RequestId>
   <HostId>cdn.aliyuncs.com</HostId>
   <Code>UnsupportedOperation</Code>
   <Message>The specified action is not supported.</Message>
</Error>

JSON example:

{
    "RequestId": "8906582E-6722-409A-A6C4-0E7863B733A5",
    "HostId": "cdn.aliyuncs.com",
    "Code": "UnsupportedOperation",
    "Message": "The specified action is not supported."
}

The CDN service will perform identity authentication for every access request. Therefore, you must contain the signature information in the request no matter whether you submit a request via the HTTP or HTTPS protocol. By using Access Key ID and Access Key Secret, the CDN performs symmetric encryption to authenticate the request sender. Access Key ID and Access Key Secret are officially issued to visitors by Alibaba Cloud (visitors can apply for and manage them on the official Alibaba Cloud website).

When a user calls a server, the following method is used to sign the request:

1. The Canonicalized Query String is constructed using the request parameters
   1. The request parameters are ordered alphabetically by the parameter names (this includes the “common request parameters” and user-defined parameters for the given request interfaces described in this document, but not the Signature parameter mentioned in “Common Request Parameters”).

      	Note
      	When a request is submitted using the GET method, these parameters are the parameter section of the request URI (i.e. the section in the URI following the “?” and connected by “&”).

   2. The name and value of each request parameter are encoded. The names and values must undergo URL encoding using the UTF-8 character set. The URL encoding rules are as follows:
      • The characters A-Z, a-z, 0-9, and “-“, “_”, “.”, “~” are not encoded.
      • Other characters are encoded in “%XY” format, with XY representing the characters’ ASCII code in hexadecimal notation. For example, the English double quotes (“) are encoded as %22.
      • Extended UTF-8 characters are encoded in “%XY%ZA…” format.
      • It must be noted that the English space ( ) is encoded as %20, rather than the plus sign (+).

        	Note
        	Generally, libraries that support URL encoding (e.g. Java’s java.net.URLEncoder) are all encoded according to the rules for the “application/x-www-form-urlencoded” MIME type. If this encoding method is used, replace the plus signs (+) in the encoded strings with %20, the asterisks (*) with %2A, and change %7E back to the tilde (~) to conform to the encoding rules described above.

   3. Connect the encoded parameter names and values with the English equals sign (=).
   4. Then, order the parameter name and value pairs connected by equals signs in alphabetical order and connect them with the & symbol to produce the Canonicalized Query String.
2. Follow the rules below to construct the string used for signature calculation by using the Canonicalized Query String constructed in the previous step:

   StringToSign=
   HTTPMethod + “&” +
   percentEncode(“/”) + ”&” +
   percentEncode(CanonicalizedQueryString)

   Here, HTTPMethod is the HTTP method used for request submission, e.g. GET.

   The percentEncode(”/”) is the encoded value (”%2F”) of the character “/”, which is obtained according to the URL encoding rules described in 1.b.

   percentEncode(CanonicalizedQueryString) is the encoded string of the Canonicalized Query String constructed in Step 1, produced by following the URL encoding rules described in 1.b.

3. According to RFC2104 definitions, use the above signature sting to calculate the signature’s HMAC value.

   	Note
   	When calculating the signature, the Key is the Access Key Secret held by the user with the “&” character (ASCII:38) added on the end. The SHA1 hashing algorithm is used.

4. According to Base64 encoding rules, encode the above HMAC value into a string. This gives you the signature value.
5. Add the obtained signature value to the request parameters as the Signature parameter. This completes the request signing process.

   	Note
   	When the obtained signature value is submitted to the CDN server as the final request parameter value, it must undergo URL encoding like other parameters according to RFC3986 rules.

   Using DescribeCdnService as an example, the request URL prior to signing is as follows:

   http://cdn.aliyuncs.com/?SignatureVersion=1.0&Format=JSON&Timestamp=2015-08-06T02:19:46Z&AccessKeyId=testid&SignatureMethod=HMAC-SHA1&Version=2014-11-11&Action=DescribeCdnService&SignatureNonce=9b7a44b0-3be1-11e5-8c73-08002700c460

   Thus, the StringToSign is:

   GET&%2F&AccessKeyId%3Dtestid&Action%3DDescribeCdnService&Format%3DJSON&SignatureMethod%3DHMAC-SHA1&SignatureNonce%3D9b7a44b0-3be1-11e5-8c73-08002700c460&SignatureVersion%3D1.0&Timestamp%3D2015-08-06T02%253A19%253A46Z&Version%3D2014-11-11

   If we assume the Access Key Id is“testid”, Access Key Secret is “testsecret”, and the Key used for HMAC calculation is “testsecret&”, the calculated signature value is:

   KkkQOf0ymKf4yVZLggy6kYiwgFs=

   The signed request URL is (note the added Signature parameter):

   http://cdn.aliyuncs.com/?SignatureVersion=1.0&Format=JSON&Timestamp=2015-08-06T02%3A19%3A46Z&AccessKeyId=testid&SignatureMethod=HMAC-SHA1&Version=2014-11-11&Signature=KkkQOf0ymKf4yVZLggy6kYiwgFs%3D&Action=DescribeCdnService&SignatureNonce=9b7a44b0-3be1-11e5-8c73-08002700c460