Use MessageBus instead of ActionCable

Transcript

1. How to use MessageBus instead of WebSockets
2. JoseLuis Torres
3. Context ❖ While a lot of web apps are expected to be notifying the user for an asynchronous action, it was not clear specially with Rails apps what should be used in order to update the UI; execute a second, third or four action as consequence of a third party API or service. ❖ This approach started as part of refactoring to an existing approach, where we used a loop to check if there was a new update from the backend using a long polling technique to see if there was a new record or a new value.
4. Disclaimer • This is how we approach our problem • It might not be the best possible approach • It worked for a current workflow • Our customers uses the app from laptops/tablets
5. Example of Workflow The user changes a budget The backend updates a record The backend creates a SM BG Job Process new raster Process Enterprise Statistics Process Multiyear scenarios Notify the front-end Notify the front-end Notify the front-end
6. Sidekiq Rails App Front End AWS:SQS Rake Post/Ajax BG Jobs Redis Previous Stack
7. Notifications RealTime apps WebSockets Long Polling
8. Our Options ❖ Action Cable ❖ Long Polling ❖ SSE
9. Action Cable ❖ Uses web sockets ❖ Needs to be deployed with a special configuration with multi-threaded web servers ❖ Uses Pub/Sub ❖ Channels ❖ Consumers ❖ Stream ❖ Subscriptions
10. Polling/Long Polling ❖ A technique to use an AJAX resource to check if something is new in the backend that will tell the front-end that it needs to be updated. ❖ Polling sets a loop with an interval of time and checks if there’s something new. ❖ Long Polling sends a requests to the backend and it comes back until there’s a response available.
11. ServerSent Events (SSE) ❖ It’s a method to communicate the server to the client in only one-way. ❖ It is supported for most of the browsers ❖ It was supported by Rails since 4.0 ❖ Persistent connection ❖ No internet Explorer
12. WebSockets ❖ Stateful connection ❖ Connection needs to be maintained, constant ❖ No need to use sessions/cookies ❖ More efficient protocol ❖ Full duplex ❖ Compatible with all browsers
13. “So, what’s wrong?”
14. Action Cable ❖ It uses it’s own server process. ❖ Uses Redis as pub/sub reference to keep track of what was broadcasted ❖ Need to use cookies to identify the current_user ❖ It needs more configuration
15. What did we do? ❖ We found a gem that can be used without a lot of hassle to communicate between the backend and the browser, and the BG jobs and the browser. ❖ It works with long polling and polling, it supports multiple clients to the same channel. ❖ Used and tested with Discourse
16. MessageBus ❖ A well maintained gem ❖ Easy to use ❖ Great for our purpose ❖ Can be used server to server ❖ Can be used server to client ❖ It uses redis ❖ It uses polling/long polling ❖ Supports all the browsers ❖ No need to have a separate instance
17. Sidekiq Rails App Front End AWS:SQS Long Term Ruby script MessageBus Client/ReactJS/Redux New Stack BG Jobs With AASM SK workers Processors State Machine that completes actions and communicate the changes to the client with MessageBus
18. New Notifications and UI State
20. Enterprise Statistics
22. Satellite Based
23. Conclusion ❖ MessageBus is a good alternative for projects where an action needs to be performed outside of the web app: ❖ Outside of controllers, models, BG jobs ❖ No need to use another server process ❖ It can be used to broadcast or send messages to user ❖ It’s rock solid
24. Thank you ❖ @joseluis_torres ❖ joseluistorres ❖ jl@joseluistorres.me