Implement SSE notifications

[lookacat]

Description

We implemented basic SSE to get notifications instantly from the server without requesting all the time.
See #9434

Related Issue

• Fixes [web] Show Notification Instantly #9434

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

Open tasks:

• ...

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[JammingBen]

Could you please elaborate a bit how it works in detail? 🙂 I'm especially interested in the token handling, what happens during token renewal? I got a 401 error from the SEE endpoint after a short while, not sure though if that was related to token renewal.

Also it doesn't work with pnpm vite for me because it always tries to connect to the wrong port (9201 instead of 9200).

[lookacat]

@JammingBen i talked to julian, he told me the connection stays open even if the token is no longer valid. Its weird that you get an 401, i will try to replicate it

[lookacat]

@JammingBen i don't get the 401 anymore at least with vite, also port 9201 should work as well as 9200

[JammingBen]

I still have 2 concerns:

• What happens if a user login is actually invalid and the server correctly returns 401? This solution will constantly try the re-establish the connection, right? Can we add some kind of retry-limit?
• An established connection won't change when the user changes their language. I assume the messages from the server come based on the Accept-Language header? In that case we also need to re-establish the connection with the updated language.

[JammingBen]

I still have 2 issues:

• When changing the language, existing SSE connections don't get terminated. You can see this by changing the language multiple times and then triggering a notification -> there will be multiple notifications.
• Notifications are not being fetched when the tab is inactive, even if I switch back to the tab. I guess we need to call the regular notifications endpoint each time we open a connection. Maybe you can do this in onOpen?

[lookacat]

alright good findings

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

46.5% Coverage
0.0% Duplication

[JammingBen]

Nice, feels very good now! 👍