Components and design
As Mark pointed out earlier, this task includes several different components:
“WP Heartbeat” API, #23216. This will do polling or long-polling so the server is able to send data and notifications to the browser. The primary use will be for setting, monitoring or taking over a post lock. Additionally it will be used to send autosave data to the server. It looks like we won’t need long-polling for now as post locks are not that time sensitive. A “standard” polling every 15 seconds would be sufficient.
Post locking. How exactly to lock a post and how a user can take over the lock? Best would be to prevent user B from being able to edit the post while user A is still writing or editing. Some ideas discussed at the IRC meetup yesterday are to overlay a transparent div over the editor and/or set the form fields to read-only. There will be a button for user B to take over the lock, clicking it will prompt user A to save the post and close the browser tab. While user B is waiting to take over, we could show a non-editable “preview” of the content (even inside the editor) updated with every “heartbeat”.
In addition we would show whether a post is being edited on the Posts screen (list table) , perhaps with the same type of button to request taking over. Other ideas welcome.
Autosave to the browser’s local storage, #23220. Keep several revisions of the content on the user’s hard drive, saving every 10 seconds and “flushing” to the server every 2 minutes (same as currently). After saving to the server (including saving a draft or publishing), empty the local storage and start again. So at the end of creating or editing a post, the local storage will be empty.
This will require “plugging into” the revisions API for restoring revisions from the local storage and some UI for letting the user recover the last revision from local storage when it exists.
Log-in expiration warnings. Update the current functionality to use the new heartbeat API and improve the UX and UI. We can detect cookies expiration earlier and show a warning that would open an iframe so the user can log in again. After that interim log-in, we will need to update all nonces.
The first feature team meeting in IRC will be next Tuesday, 22 January at 1pm PST / 21:00 UTC. Please join us if you’re interested in participating in the development of any of the above components.