Help Center> API Gateway> Developer Guide> Calling APIs Through App Authentication> C#
Updated on 2024-01-29 GMT+08:00
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C#

Scenarios

To use C# to call an API through app authentication, obtain the C# SDK, open the project file in the SDK, and then call the API by referring to the API calling example.

Prerequisites

  • You have obtained API calling information. For details, see Preparation.
  • You have installed Visual Studio 2019 version 16.8.4 or a later version. If not, download it from the official Visual Studio website and install it.

Obtaining the SDK

Log in to the APIG console, and download the SDK on the SDKs page by referring to section "SDKs" in the API Gateway User Guide.

Alternatively, download the latest SDK version. Then obtain the ApiGateway-csharp-sdk.zip package. The following table shows the files decompressed from the package.

Name

Description

apigateway-signature\Signer.cs

SDK code

apigateway-signature\HttpEncoder.cs

sdk-request\Program.cs

Sample code for signing requests

backend-signature\

Sample project for backend signing

csharp.sln

Project file

licenses\license-referencesource

Third-party license

Opening a Project

Double-click csharp.sln in the SDK package to open the project. The project contains the following:

  • apigateway-signature: Shared library that implements the signature algorithm. It can be used in the .Net Framework and .Net Core projects.
  • backend-signature: Example of a backend service signature.
  • sdk-request: Example of invoking the signature algorithm. Modify the parameters as required. For details about the sample code, see API Calling Example.

API Calling Example

  1. Import the C# SDK to your project.

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    using APIGATEWAY_SDK;

  2. Generate a new signer and enter the AppKey and AppSecret.

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    Signer signer = new Signer();
// Directly writing AK/SK in code is risky. For security, encrypt your AK/SK and store them in the configuration file or environment variables.
// In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, set environment variables HUAWEICLOUD_SDK_AK and HUAWEICLOUD_SDK_SK.
signer.Key = Environment.GetEnvironmentVariable("HUAWEICLOUD_SDK_AK");
signer.Secret = Environment.GetEnvironmentVariable("HUAWEICLOUD_SDK_SK");

  3. Generate an HttpRequest, and specify the method, request URL, and body.

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    HttpRequest r = new HttpRequest("POST",    
                    new Uri("https://c967a237-cd6c-470e-906f-a8655461897e.apigw.exampleRegion.com/app1?query=value"));
r.body = "{\"a\":1}";

  4. Add the x-stage header to the request to specify an environment name. Add other headers to be signed as necessary.

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    r.headers.Add("x-stage", "RELEASE");

  5. Execute the following function to generate HttpWebRequest, and add the X-Sdk-Date and Authorization headers for signing the request:

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    HttpWebRequest req = signer.Sign(r);

  6. Access the API and view the access result.

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    var writer = new StreamWriter(req.GetRequestStream());
writer.Write(r.body);
writer.Flush();
HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
var reader = newStreamReader(resp.GetResponseStream());
Console.WriteLine(reader.ReadToEnd());