An upload callback refers to a process in which the client includes a callback (Callback) parameter in its request. After the upload is complete, the server sends a synchronous POST callback request to the third-party application server specified in the Callback parameter. The server returns all results to the client only after receiving confirmation and a response from the third-party application server.

Sample Code

Implementation of Upload Callback in Standard Upload

import { TosClient, TosClientError, TosServerError } from '@volcengine/tos_harmonyos_sdk';​
​
​
const client = new TosClient({​
  accessKeyId: "Provide your ak", ​
  accessKeySecret: "Provide your sk", ​
  securityToken: 'Provide your securityToken',​
  region: "Provide your region", ​
  endpoint: "Provide your endpoint", ​
});​
​
function handleError(error: Error) {​
  if (error instanceof TosClientError) {​
    console.log('Client Err Msg:', error.message);​
    console.log('Client Err Stack:', error.stack);​
  } else if (error instanceof TosServerError) {​
    console.log('Request ID:', error.requestId);​
    console.log('Response Status Code:', error.statusCode);​
    console.log('Response Header:', error.headers);​
    console.log('Response Err Code:', error.code);​
    console.log('Response Err Msg:', error.message);​
  } else {​
    console.log('unexpected exception, message: ', error);​
  }​
}​
​
async function main() {​
  try {​
    const callbackUrl = '*** Provide your callback url ***';​
    const objectKey = '*** Provide your object key ***';​
​
   ​
   ​
    const callback = `​
    {​
      "callbackUrl" : "${callbackUrl}", ​
      "callbackBody" : ${'"{\\"bucket\\": ${bucket}, \\"object\\": ${object}, \\"key1\\": ${x:key1}}"'}, ​
      "callbackBodyType" : "application/json"                ​
    }`;  ​
    ​
    const callbackVar = `​
    {​
      "x:key1" : "ceshi"​
    }`;​
    const res = await client.putObject({​
      Bucket: bucketName,​
      Key: objectKey,​
      Content: buffer.from('object content').buffer,​
      Callback: buffer.from(callback).toString('base64'),​
      CallbackVar: buffer.from(callbackVar).toString('base64'),​
    });​
    console.log('putObject CallbackResult: ', res.CallbackResult);​
  } catch (error) {​
    handleError(error);​
  }​
}​
​
main();​

Multipart upload callback

import { TosClient, TosClientError, TosServerError } from '@volcengine/tos_harmonyos_sdk';​
​
​
const client = new TosClient({​
  accessKeyId: "Provide your ak", ​
  accessKeySecret: "Provide your sk", ​
  securityToken: 'Provide your securityToken',​
  region: "Provide your region", ​
  endpoint: "Provide your endpoint", ​
});​
​
function handleError(error: Error) {​
  if (error instanceof TosClientError) {​
    console.log('Client Err Msg:', error.message);​
    console.log('Client Err Stack:', error.stack);​
  } else if (error instanceof TosServerError) {​
    console.log('Request ID:', error.requestId);​
    console.log('Response Status Code:', error.statusCode);​
    console.log('Response Header:', error.headers);​
    console.log('Response Err Code:', error.code);​
    console.log('Response Err Msg:', error.message);​
  } else {​
    console.log('unexpected exception, message: ', error);​
  }​
}​
​
async function main() {​
  try {​
    const callbackUrl = '*** Provide your callback url ***';​
    const callback = `​
    {​
      "callbackUrl" : "${callbackUrl}",​
      "callbackBody" : ${'"{\\"bucket\\": ${bucket}, \\"object\\": ${object}, \\"key1\\": ${x:key1}}"'},​
      "callbackBodyType" : "application/json"​
    }`;  ​
​
    const callbackVar = `​
    {​
      "x:key1" : "ceshi"​
    }`;​
    const bucketName = 'harmony-sdk-test-bucket';​
    const objectName = 'example_dir/multipartExample';​
   ​
    const filePath = './example_dir/multipartExample';​
   ​
    const res = await client.createMultipartUpload({​
      Bucket: bucketName,​
      Key: objectName,​
      ACL: ACLType.ACLPrivate,​
      StorageClass: StorageClassType.StorageClassIa,​
    });​
    console.log('CreateMultipartUploadV2 Upload ID:', res.UploadId);​
​
    const stats = await fs.statSync(filePath);​
​
    const totalSize = stats.size;​
​
    const partSize = 5 * 1024 * 1024;​
    let offset = 0;​
  ​
    let partNumber = 1;​
    const partsInfo: UploadedPart[] = [];​
    while (offset < totalSize) {​
      const uploadResult = await client.uploadPart({​
        Bucket: bucketName,​
        Key: objectName,​
        PartNumber: partNumber,​
        UploadID: res.UploadId,​
        Content: fs.createReadStream(filePath, {​
          start: offset,​
          end: offset + partSize - 1,​
        }),​
      });​
      const eTag = uploadResult.ETag;​
      console.log(`partNumber${partNumber} Etag:`, eTag);​
      partsInfo.push(new UploadedPart(partNumber, eTag));​
      partNumber++;​
      offset += partSize;​
    }​
    console.log('parts information', partsInfo);​
​
​
    const completeRes = await client.completeMultipartUpload({​
      Bucket: bucketName,​
      Key: objectName,​
      UploadID: res.UploadId,​
      Parts: partsInfo,​
      Callback: buffer.from(callback).toString('base64'),​
      CallbackVar: buffer.from(callbackVar).toString('base64'),​
    });​
​
    console.log('result callback result:', completeRes.CallbackResult);​
  } catch (error) {​
    handleError(error);​
  }​
}​
​
main();​

Relevant Documentation

For a detailed introduction to upload callback, please refer to Upload Callback.

Last updated: 2025.09.26 19:05:15

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