How to Implement Chunked and Resumable Uploads for Gigabyte‑Size Files

Chunked Upload

Chunked upload means dividing the file to be uploaded into multiple data blocks (often called parts) according to a predefined rule such as size, uploading each part separately, and finally letting the server combine all received parts back into the original file.

Resumable Upload

Resumable upload works similarly to the download managers like Xunlei or eMule: the task is split into several sections, each handled by a thread. If a network failure occurs, the upload can continue from the already‑uploaded sections instead of restarting from the beginning.

Use Cases

Resumable upload essentially starts from a chunked upload, so its applicable scenarios are the same as those for chunked uploading.

Implementation Steps

Split the file into equal‑sized parts according to a pre‑agreed rule.

Initialize an upload task and obtain a unique identifier for the parts.

Send each part according to a chosen transmission strategy.

After all parts are sent, the server checks the upload completion status and merges the parts into the original file.

The article concludes with an invitation for readers to discuss the implementation in the comments.