Support push notifications for Mailbox

[alagane]

Push documentation https://jmap.io/spec-core.html#push

We should be able to open a communication channel using websockets to receive StateChange notifications.
The library should take care of the authentication.

For an authentication and request example using ticket on James: https://github.com/linagora/tmail-backend/pull/78/files#diff-652928d50d74bf6233709ab2fb095e4909b554d8e6b3ede18785277964803795

• Get the ticket (using the url on the session)
• Use the ticket to open a websocket connection (query parameter)
• Filter to get only mailboxes ones (will probably need rxjs observables) this is about filtering them when different entities will be subscribed, we will need to be able to get one observable for each kind but only one websocket opened

Given a client with session fetched
When call the method to get push notifications
And there is an error getting the ticket (Authentication)
Then the returned observable throws an error

Given a client with session fetched
When call the method to get push notifications
And there is an error opening the websocket (with ticket)
Then the returned observable throws an error

Given a client with session fetched
When call the method to get Mailbox push notifications
And a Mailbox is added
Then the returned observable emits the StateChange for the Mailbox
TODO How do we know the observable is ready to receive StateChange when the Mailbox is added?

Given a client with session fetched
When call the method to get Mailbox push notifications
And an Email is added
Then the returned observable does not emit the StateChange for the Email
TODO How do we know the observable is ready to receive StateChange when the Mailbox is added?

[chibenwa]

@alagane can you describe a bit more the work to be done, and add a Definition of done?

[alagane]

Added these lines.

We should be able to open a communication channel using websockets to receive StateChange notifications.
The library should take care of the authentication.

For now we encounter problems with authentication, because it is not possible to send HTTP headers with websockets for web browsers, and this is blocking. See https://github.com/linagora/james-project-private/pull/99

[chibenwa]

What do we do once we receive StateChanges from the library?

[alagane]

What do we do once we receive StateChanges from the library?

Well, it is not the responsibility of the library I suppose. Library user can make a /changes request then.

[Arsnael]

By lib user you mean inbox app?

[alagane]

By lib user you mean inbox app?

Yes, but there could be other lib users.

[Arsnael]

Yes, but there could be other lib users.

For sure, I just wanted to be sure of the meaning here. Thanks :)