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
   3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e
   CertUtil: -hashfile command executed.
   3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e

   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.

   Table 1 SDK packages and the corresponding SHA-256 values

   Language	SHA-256 Value of the SDK Package
   Java	3a86f1ba249a00727db506e4075ec9630e6cf74f312bddf6c3901c9d0786f53e
   Go	23734867eae2e7ef61427c64aa33aa89512571946f2f43a1a5fef5e801e3129f
   Python	57636d8bacc459cab9dc08c70d01ccc42391ace60e6960c4e947566da1dc5d26
   C#	e5a3b677f75c28ba3f1e16645d8171f7b6f34a42143f8a32a68bb18719b5e65d
   JavaScript	442ac2fcb41d84525dc0139ec3f05d190e4e337cdbcdfdfc82a09d79d2ecd25e
   PHP	2cc76bd2ecd48f00899d18b0f76d05ce2623065180f111c3f70ac14ddf0506f3
   C++	2a54c3f2486d562ea6af1384eca40b301918bdc02f98bbf2c114f282dc059c00
   C	4957556c108e0174d55b4b8d720f296967a9367ca54010792b1b3de039b87363
   Android	0fdcc6fd93a68dce5c3e1b8e6370cc9340429cabfb0f268c3f9e5ea05238ae96

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.

   // Coded or plaintext AK and SK pose significant security risks. To ensure security, encrypt your AK and SK, store them in configuration files or environment variables, and decrypt them when needed.
   // In this example, the AK and SK stored in the environment variables are used for identity authentication. Before running this example, configure environment variables SDK_AK and SDK_SK in the local environment.
   ak = os.Getenv("SDK_AK");
   sk = os.Getenv("SDK_SK");
   
   s := core.Signer{
   	Key:    ak,
   	Secret: sk,
   }

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)