# Response

#### Status Code

After sending a request, you will receive a response, including a status code, response header, and response body.

A status code is a group of digits, ranging from 1xx to 5xx. It indicates the status of a request. For more information, see Status Codes.

For example, if status code 201 is returned for calling the API used to obtain a user token, the request is successful.

#### Response Header

Similar to a request, a response also has a header, for example, Content-Type.

Figure 1 shows the response header fields for the API used to obtain a user token. The x-subject-token header field is the desired user token. This token can then be used to authenticate the calling of other APIs.

Figure 1 Header fields of the response to the request for obtaining a user token

#### (Optional) Response Body

The body of a response is often returned in structured format as specified in the Content-Type header field, such as JSON or XML. The response body transfers content except the response header.

The following is part of the response body for the API used to obtain a user token.

    {
        "token": {
            "expires_at": "2019-02-13T06:52:13.855000Z",
            "methods": [
                "password"
            ],
            "catalog": [
                {
                    "endpoints": [
                        {
                            "region_id": "******",
    ......

If an error occurs during API calling, an error code and a message will be displayed. The following shows an error response body.

    {
        "error_msg": "The format of message is error",
        "error_code": "AS.0001"
    }

In the response body, error_code is an error code, and error_msg provides information about the error.

Parent topic: Calling APIs