Help Center/ IAM Identity Center/ API Reference/ Calling APIs/ Making an API Request
Updated on 2024-04-10 GMT+08:00
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Making an API Request

This section describes the structure of a REST API request and use the API for listing instances as an example to describe how to call an API.

Request URI

A request URI is in the following format:

{URI-scheme} :// {Endpoint} / {resource-path} ? {query-string}

Table 1 Request URL

Parameter

Description

URI-scheme

Protocol used to transmit requests. All APIs use HTTPS.

Endpoint

Domain name or IP address of the server bearing the REST service. The endpoint varies between services in different regions. It can be obtained from Regions and Endpoints. For example, the endpoint of IAM Identity Center is identitycenter.myhuaweicloud.com.

resource-path

Access path of an API for performing the specified operation. Obtain the path from the URI of an API. For example, the resource-path of the API for listing instances is /v1/instances.

query-string

An optional query parameter. Ensure that a question mark (?) is included before each query parameter that is in the format of Parameter name=Parameter value. For example, ?limit=10 indicates that a maximum of 10 data records will be queried.

For example, to list instances in IAM Identity Center, obtain the endpoint of IAM Identity Center (identitycenter.myhuaweicloud.com) and find resource-path (/v1/instances) in the URI of the API for Listing Instances. Then, construct the URI as follows:

1
 
https://identitycenter.myhuaweicloud.com/v1/instances

To simplify the URI display in this document, each API is provided only with a resource-path and a request method. The URI-scheme value of all APIs is HTTPS, and the endpoints of all APIs in the same region are identical.

Request Methods

The HTTP protocol defines the following request methods that can be used to send a request to the server:

  • GET: requests the server to return specified resources.
  • PUT: requests the server to update specified resources.
  • POST: requests the server to add resources or perform special operations.
  • DELETE: requests the server to delete specified resources, for example, an object.
  • HEAD: requests the server to return the response header.
  • PATCH: requests the server to update partial content of a specified resource. If the resource does not exist, a new resource will be created.

For example, in the URI of the API used to list instances, the request method is GET. The request is as follows:

GET https://identitycenter.myhuaweicloud.com/v1/instances

Request Header

You can also add additional header fields to a request, such as the fields required by a specified URI or HTTP method. For example, to request for the authentication information, add Content-Type, which specifies the request body type.

Common request headers are as follows:

  • Content-Type (mandatory): specifies the type or format of the message body. The default value is application/json.
  • Authorization (mandatory): specifies the signature information contained in the request. For details about AK/SK authentication, see AK/SK Authentication.
  • X-Sdk-Date (mandatory): specifies the time when the request was sent, for example, 20221107T020014Z.
  • Host (mandatory): specifies the host address, for example, identitycenter.myhuaweicloud.com.

    APIs support AK/SK authentication, which uses SDKs to sign a request. During the signature, the Authorization (signature information) and X-Sdk-Date (time when the request is sent) headers are automatically added in the request. For details about AK/SK authentication, see AK/SK Authentication.

For the API in Listing Instances, the request is as follows:

GET https://identitycenter.myhuaweicloud.com/v1/instances
content-type: application/json
X-Sdk-Date: 20230330T021902Z 
host: identitycenter.myhuaweicloud.com
Authorization: SDK-HMAC-SHA256 Access=xxxxxxxxxxxxxxxxxxx, SignedHeaders=content-type;host;x-sdk-date, Signature=xxxxxxxxxxxxxxxxxxxx

(Optional) Request Body

The body of a request is often sent in a structured format as specified in the Content-Type header field. The request body transfers content except the request header.

The request body varies between APIs. Some APIs do not require the request body, such as the APIs requested using the GET and DELETE methods.

Parent topic: Calling APIs