The `FileSystemObserver` interface

[a-sully]

こんにちは TAG-さん!

I'm requesting a TAG review of the FileSystemObserver interface for the File System specification.

This proposal introduces a FileSystemObserver interface which will much more easily allow a website to be notified of changes to the file system.

The file system is a shared resource that can be modified from several contexts. A Bucket File System (a.k.a. an Origin Private File System, or OPFS) spans numerous agents - tabs, workers, etc - within the same storage key. The local file system also spans across origins and other applications on the host operating system.

Currently, for a given agent to know about modifications to the file system - made either by itself or from some external context - it must poll the file system to detect changes. This is inefficient and does not scale well.

• Explainer: https://github.com/whatwg/fs/blob/main/proposals/FileSystemObserver.md
• Security and Privacy self-review: No changes to the existing review, though that review needs to be updated to consider interaction with pages which are not fully active. In the meantime, this feature’s interaction with non-fully-active pages is discussed here. See also the Permissions Considerations and Fingerprinting Risk sections of the explainer
• GitHub repo: whatwg/fs
• Primary contacts (and their relationship to the specification):
  • Austin Sullivan (@a-sully), Google Chrome
• Organization/project driving the design: Google/Chromium
• External status/issue trackers for this feature: https://chromestatus.com/feature/4622243656630272

Further details:

• [x] I have reviewed the TAG's Web Platform Design Principles
• The group where the incubation/design work on this is being done: whatwg/fs and WICG/file-system-access
• The group where standardization of this work is intended to be done: whatwg/fs
• Existing major pieces of multi-stakeholder review or discussion of this design: Developers have enumerated several use cases, discussed various designs, and provided example code for how file paths can be watched with the existing APIs in https://github.com/WICG/file-system-access/issues/72. No discussion with other stakeholders yet
• Major unresolved issues with or opposition to this design:
• This work is being funded by: Google

You should also know that...

The proposed interface can be used to observe both files on the user's local device (as specified in WICG/file-system-access) and files in the Bucket File System (as specified in whatwg/fs).

We'd prefer the TAG provide feedback as (please delete all but the desired option):

🐛 open issues in our GitHub repo for each point of feedback

[torgo]

Hi @a-sully this unfortunately seems to have dropped off our radar and we did not get to it in a timely fashion. My apologies. Can you update us on the latest status of this proposal? Also it would be good to understand the multi-stakeholder situation - especially any support from other browsers. That will help us get you an answer quickly.

[a-sully]

Hi @a-sully this unfortunately seems to have dropped off our radar and we did not get to it in a timely fashion. My apologies. Can you update us on the latest status of this proposal?

Sure thing! This feature is currently being prototyped in Chromium. It's a very highly requested feature from developers that we're hoping to get into their hands sometime early next year

Also it would be good to understand the multi-stakeholder situation - especially any support from other browsers. That will help us get you an answer quickly.

My apologies for forgetting to file the standards position issues months ago. I have discussed this idea in the abstract with some folks from other browsers in the past, though I believe that was before a concrete proposal was made. I've now filed https://github.com/mozilla/standards-positions/issues/942 and https://github.com/WebKit/standards-positions/issues/291 to solicit their input :)

[cynthia]

We reviewed this during our F2F, and the feature looks great! Thanks for bringing this to our attention.

If there are any negative signals from other implementors that may require a significant change, please let us know and we can reopen for further discussion.