Upload Post-Processing

[Acconut]

Most files will be processed after their upload in some form, for example:

• moving to another storage location
• retracting information (e.g. image dimension)
• encoding videos

While these post-processing steps are application-specific, tus does not have any special support for communication the post-processing or its results back to the client. Originally, the decision to exclude this was intentional because tus should focus on the uploading itself, not any of the subsequent steps. However, this also leads to issues such as https://github.com/tus/tus-js-client/issues/557. Hence, I think tus should have some capability to communicate this post-processing back to the client.

The requirements of such an extension are:

• It should provide the result of the post-processing to the client after an upload is completed (either directly or indirectly by pointing to a resource which provide the results)
• The retrieval of the results (or their location) should be retriable, so clients can retry if a previous request failed
• The mechanism should take into consideration that results may not be immediately available after the upload is completed, but with some delay.