5 Ways to Build Real-Time Apps with Ruby and NoSQL

WebSockets with Action Cable and Redis backing

WebSockets with Action Cable and Redis backing remain the most straightforward way to build real-time apps with Ruby and NoSQL, wiring persistent connections to channels that broadcast updates with minimal latency. Action Cable integrates WebSockets into Rails with connections, channels, and streams, while Redis backing fans out messages across multiple app instances for horizontal scale in real-time apps. In newer stacks, Rails 8’s Solid Cable and database-backed pub/sub can reduce Redis dependency, but Redis backing is still a proven backbone for WebSockets and Action Cable in production real-time apps.guides.rubyonrails+4​youtube​

• To stabilize WebSockets with Action Cable, configure heartbeats, connection limits, and back-off on reconnects; Redis backing keeps broadcasts consistent when pods autoscale in real-time apps with Ruby.stanko+1​
• For high fan-out, shard channels by key and use Redis stream patterns so WebSockets with Action Cable sustain throughput in real-time apps with NoSQL backends.appsignal+1​

Change streams in MongoDB for live updates

Change streams in MongoDB for live updates let servers subscribe to inserts, updates, and deletes and push events over WebSockets to power real-time apps with Ruby and NoSQL. MongoDB change streams expose a watch cursor at collection, database, or deployment scope, filtering via aggregation so only relevant live updates reach subscribers. The official Ruby driver supports change streams, making change streams in MongoDB a first-class trigger for Action Cable or AnyCable broadcasts in real-time apps.leocode+2​

• Ensure replica sets and proper read concern to use change streams in MongoDB for live updates at scale, especially on sharded clusters feeding real-time apps with Ruby.xuchao+1​
• Map each change stream event to a domain event before broadcasting so live updates remain stable even as schemas evolve in NoSQL-backed real-time apps.mongodb+1​

Event sourcing with append-only logs

Event sourcing with append-only logs stores every fact as an immutable event, allowing real-time apps with Ruby and NoSQL to rebuild state and stream projections efficiently. An append-only log aligns with Kafka, Redis Streams, or NoSQL collections, and Ruby services can append and replay events to publish consistent updates to WebSockets or APIs. By treating the log as the source of truth, event sourcing with append-only logs simplifies auditing and temporal queries in real-time apps with Ruby.kurrent+1​

• Keep event schemas versioned and add projection rebuilders so event sourcing with append-only logs survives refactors in NoSQL-centric real-time apps.kurrent​
• When throughput is extreme, partition the append-only log by aggregate to avoid hot shards in real-time apps with Ruby and NoSQL.stackoverflow+1​

Backpressure handling on bursty workloads

Backpressure handling on bursty workloads is critical for real-time apps with Ruby and NoSQL because producers can overwhelm WebSockets or databases. Implement bounded queues per connection, apply server-side pause/resume, and monitor WebSocket bufferedAmount to detect client lag as part of backpressure handling on bursty workloads. Rate-limit publish loops and drop/summarize low-priority messages so backpressure handling on bursty workloads preserves tail latency for high-value streams in real-time apps.skylinecodes.substack+1​

• Use circuit breakers and load shedding to protect Redis/Mongo during spikes; coordinated backpressure handling on bursty workloads prevents cascading failures in real-time apps with Ruby.dev​
• Expose metrics and alarms around queue depth and send buffer saturation to tune backpressure handling on bursty workloads continuously.skylinecodes.substack​

SLA-aware fallbacks during NoSQL outages

SLA-aware fallbacks during NoSQL outages keep real-time apps with Ruby responsive when a NoSQL dependency degrades or fails. Combine timeouts, retries with jitter, and circuit breakers to trigger SLA-aware fallbacks during NoSQL outages, serving cached or approximate data within SLOs rather than timing out. Document priority paths that must return deterministic responses, and route non-critical updates to queues to drain later as part of SLA-aware fallbacks during NoSQL outages.youtube​daily​

• Maintain read-only modes, stale-while-revalidate caches, and graceful degradation banners so SLA-aware fallbacks during NoSQL outages are predictable to users of real-time apps.youtube​
• Track fallback invocations and error budgets; SLA-aware fallbacks during NoSQL outages are only effective when observability guides when to fail open vs. fail closed in Ruby services.daily​youtube​

By combining WebSockets with Action Cable and Redis backing, change streams in MongoDB for live updates, event sourcing with append-only logs, backpressure handling on bursty workloads, and SLA-aware fallbacks during NoSQL outages, teams can deliver robust real-time apps with Ruby and NoSQL. These five ways complement each other: Redis-backed WebSockets distribute updates, MongoDB change streams trigger live events, append-only logs ensure auditability, backpressure keeps pipelines stable, and SLA-aware fallbacks keep SLAs during outages for real-time apps at scale.guides.rubyonrails+3​youtube​

1. https://guides.rubyonrails.org/action_cable_overview.html
2. https://dev.to/shettigarc/building-real-time-apps-with-rails-8-hotwire-actioncable-in-production-19fa
3. https://www.youtube.com/watch?v=bOlrHbhLzZE
4. https://www.heroku.com/blog/real_time_rails_implementing_websockets_in_rails_5_with_action_cable/
5. https://blog.appsignal.com/2024/05/01/anycable-for-ruby-on-rails-how-does-it-improve-over-action-cable.html
6. https://github.com/dazralsky/actioncable
7. https://stanko.io/monitoring-actioncable-GdeaeHfIU4Yk
8. https://leocode.com/development/4-ways-to-get-real-time-database-updates-from-mongodb/
9. https://www.xuchao.org/docs/mongodb/changeStreams.html
10. https://www.mongodb.com/docs/ruby-driver/current/logging-and-monitoring/change-streams/
11. https://www.kurrent.io/blog/event-sourcing-audit
12. http://oierud.net/bliki/EventSourcingInRuby.html
13. https://stackoverflow.com/questions/26843088/append-only-log-event-database
14. https://skylinecodes.substack.com/p/backpressure-in-websocket-streams
15. https://dev.to/ably/challenges-of-scaling-websockets-3493
16. https://www.youtube.com/watch?v=xTpjg2Q2NC4
17. https://daily.dev/blog/dbaas-slas-what-to-know-in-2024
18. https://revs.runtime-revolution.com/implementing-websockets-in-ruby-on-rails-with-action-cable-056ca78cf555
19. https://ruby-doc.org/blog/ruby-meets-high-frequency-data-handling-real-time-streams/
20. https://www.hellointerview.com/learn/system-design/in-a-hurry/core-concepts