Go

Scenarios

To use Go to call an API through App authentication, obtain the Go SDK, create a project, and then call the API by referring to the API calling example.

This section uses IntelliJ IDEA 2018.3.5 as an example.

Prerequisites

• You have obtained the domain name, ID, request URL, and request method of the API to be called, and the AppKey and AppSecret of the App for calling the API. For more information, see Preparation.
• You have installed the Go programming language. If not, download the Go installation package from the official Go website and install it.
• You have installed IntelliJ IDEA. If not, download IntelliJ IDEA from the official IntelliJ IDEA website and install it.
• You have installed the Go plug-in on IntelliJ IDEA. If not, install the Go plug-in according to Figure 1.
  Figure 1 Installing the Go plug-in
  

Obtaining the SDK

1. Log in to the DataArts Studio console.
2. Click DataArts DataService.
3. In the navigation pane, choose DataArts DataService Exclusive > SDKs.
4. On the SDKs page, download the SDK package.
5. Verify integrity of the SDK package. In Windows, open the CLI and run the following command to generate the SHA-256 value of the downloaded SDK package. In the command, D:\java-sdk.zip is an example local path and name of the SDK package. Replace it with the actual value.

   certutil -hashfile D:\java-sdk.zip SHA256

   The following is an example command output:

   SHA-256 hash value of D:\java-sdk.zip
   a7c0195ebf297f29ab0065da16d7e84f14911de177e6e0c8dbadf3464d12b75f
   CertUtil: -hashfile command executed.

   Compare the SHA-256 value of the downloaded SDK package with that provided in the following table. If they are the same, no tampering or packet loss occurred during the package download.

   Language	SHA-256 Value of the SDK Package
   Java	a7c0195ebf297f29ab0065da16d7e84f14911de177e6e0c8dbadf3464d12b75f
   Go	caf22350181a4ecd49dc0d3f56097b10c1794792adae407140950be4ed9b6771
   Python	c80b9ef282fc88d3fb16db4cb9d7525d3db71f7989782ed0b636920ea2fadb93
   C#	b0e69ef60a561c54c1b86c3447ca855088a1fa2a672fbfba618aaf56b2841e8a
   JavaScript	c64e595651de079766e446ce2c3262013256f81683bb9434bee27bed3a4caf01
   PHP	e2eba2cae72aea794edb4057ed8eb7cb82f0dbaccabf9c5539694a7a7a9f3c89
   C++	c173f59d816aba53f47750cf5ffdc65cc345b1613974b3d2a545ace48787f577
   C	e4f22beb7b132fe6e57c9de79f596c3ff830228cd7221b02ca96198e501c642c
   Android	d6c3032801ac88cf8cbc51f64d42457174447c8d159f34a187c036913b31ea2b

Obtain the ApiGateway-go-sdk.zip package. The following table shows the files decompressed from the package.

Creating a Project

1. Start IntelliJ IDEA and choose File > New > Project.

   On the displayed New Project page, choose Go and click Next.

   Figure 2 New Project
   

2. Click ..., select the directory where the SDK is decompressed, and click Finish.
   Figure 3 Selecting the SDK directory after decompression
   

3. View the directory structure shown in the following figure.
   Figure 4 Directory structure of the new project
   

   Modify the parameters in sample code demo.go as required. For details about the sample code, see API Calling Example.

API Calling Example

1. Import the Go SDK (signer.go) to the project.

   import "apig-sdk/go/core"

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

   s := core.Signer{
           Key: "4f5f626b-073f-402f-a1e0-e52171c6100c",
           Secret: "******",
   }

3. Generate a new request, and specify the domain name, method, request URL, query parameters, and body.

   r, _ := http.NewRequest("POST", "http:/{apig-endpoint}/api?a=1&b=2",
                            ioutil.NopCloser(bytes.NewBuffer([]byte("foo=bar"))))

4. Add a header to the request. The header contains specific parameters. Add other headers to be signed as necessary.

   r.Header.Add("x-stage", "RELEASE")
   r.Header.Add("name","value")

5. Execute the following function to add the X-Sdk-Date and Authorization headers for signing: Then, add the x-Authorization header to the request. The value of the x-Authorization header is the same as that of the Authorization header.

   s.Sign(r)
   authorization := r.Header.Get("Authorization")
   r.Header.Add("x-Authorization", authorization)

6. Access the API and view the access result.

   resp, err := http.DefaultClient.Do(r)
   body, err := ioutil.ReadAll(resp.Body)