Object Storage Service:Upload callbacks (Android SDK)

How it works

1. The client submits an upload request with callback parameters — Include callbackUrl, callbackHost, callbackBody, and callbackBodyType in the PutObjectRequest.

2. OSS stores the object and sends a POST request — After the object is stored, OSS sends a POST request to the URL specified in callbackUrl.

3. Your server processes the callback and returns a response — The server must return a JSON response. HTTP 200 indicates success; any other status code indicates failure.

4. OSS returns the final result to the client — After receiving a successful callback response, OSS returns the upload result to the client.

Prerequisites

Before you begin, ensure that you have:

• An initialized OSSClient instance. For setup instructions, see Initialization

Callback parameters

Set the following parameters using setCallbackParam():

Configure an upload callback

The following example uploads an object and configures a callback to http://oss-demo.aliyuncs.com:23450. After a successful upload, OSS POSTs the object's MIME type and size to that URL, and the client reads the server's JSON response.

// Create an upload request.
// Specify the bucket name, the full path of the object, and the full path of the local file.
// Example values: examplebucket, exampledir/exampleobject.txt, /storage/emulated/0/oss/examplefile.txt
// The full path of the object cannot contain the bucket name.
PutObjectRequest put = new PutObjectRequest("examplebucket", "exampledir/exampleobject.txt", "/storage/emulated/0/oss/examplefile.txt");

put.setCallbackParam(new HashMap<String, String>() {
    {
        put("callbackUrl", "http://oss-demo.aliyuncs.com:23450");
        put("callbackHost", "yourCallbackHost");
        put("callbackBodyType", "application/json");
        put("callbackBody", "{\"mimeType\":${mimeType},\"size\":${size}}");
    }
});

OSSAsyncTask task = oss.asyncPutObject(put, new OSSCompletedCallback<PutObjectRequest, PutObjectResult>() {
    @Override
    public void onSuccess(PutObjectRequest request, PutObjectResult result) {
        Log.d("PutObject", "UploadSuccess");

        // serverCallbackReturnJson contains data only if a callback was configured.
        String serverCallbackReturnJson = result.getServerCallbackReturnBody();

        Log.d("servercallback", serverCallbackReturnJson);
    }

    @Override
    public void onFailure(PutObjectRequest request, ClientException clientExcepion, ServiceException serviceException) {
        // Handle exceptions.
    }
});

Configure custom variables

Use setCallbackVars() to define custom variables and reference them in callbackBody using the ${x:varname} syntax.

put.setCallbackParam(new HashMap<String, String>() {
    {
        put("callbackUrl", "http://oss-demo.aliyuncs.com:23450");
        put("callbackHost", "yourCallbackHost");
        put("callbackBodyType", "application/json");
        put("callbackBody", "{\"object\":${object},\"size\":${size},\"my_var1\":${x:var1},\"my_var2\":${x:var2}}");
    }
});

put.setCallbackVars(new HashMap<String, String>() {
    {
        put("x:var1", "value1");
        put("x:var2", "value2");
    }
});

Verify callback authenticity

If your callback endpoint is publicly accessible, verify that callback requests originate from OSS by checking the request signature. For the signature verification procedure, see Callback.

What's next

• For the complete sample code, see GitHub.

• For the callback API specification, including request format and signature verification, see Callback.

• For OSSClient setup, see Initialization.