Draft v1 Update for Resumable Uploads

Hi all,

Our previous resumable upload draft generated a lot of discussions. I’m glad to announce that we have a new draft ready to address many feedbacks that suggested adopting the PATCH method. In this draft, we split the Upload Transfer Procedure into 2 separate procedures: Upload Creation Procedure and Upload Appending Procedure.


1. Content-Range

We attempted adopting Content-Range header, however, we realized that it doesn’t support unknown lengths which is an important use case that our clients require. Therefore we kept Upload-Offset and Upload-Incomplete headers.

We are open to discuss other options, such as modifying the semantics of the Content-Range header if that’s preferred, although it might cause more breakages than defining new headers.

2. Media types

PATCH currently doesn’t define a media type. We went through the list of media types but couldn’t find the appropriate category for the Upload Appending Procedure. It is a generic byte-appending operation that can modify any types of media, so we don’t think it fits into an application media type.

We are open to suggestions if a media type is desired.

3. 1xx intermediate response

We surveyed the most popular HTTP libraries in many languages, and nearly all of them consider 1xx responses an internal signaling mechanism so they don’t expose the ability for applications to handle them. (We are also guilty of this as maintainers of URLSession API on Apple platforms.) If we use 1xx response for any critical information, it would prevent nearly all tus-v1 adopters to switch to this new protocol until it’s natively supported in HTTP libraries.

We think having just the feature detection part using 1xx response is a good balance, both eliminating any extra round trips for HTTP libraries implementing this protocol and allowing application adopters to ignore it.

4. Can we PATCH a PATCH?

Yes, Upload Creation Procedure supports any method, including PATCH. We included a section “Request Identification” about the nuances in this area. Unfortunately, this added complexity is the result of splitting the procedures, but we don’t think it will complicate the implementations in most cases. Servers can still decide what methods make sense for their use case and whether to support PATCH.

Looking forward to continuing the discussions and refinements of the draft.

Best regards,
Guoye Zhang

Received on Thursday, 16 June 2022 21:31:28 UTC