How do I set up Cable with the Lucky framework?

Mount the Cable::Handler middleware before Lucky::RouteHandler in app_server.cr, configure settings in cable.cr, and implement connection and channel classes, as detailed in the README's Lucky example. Ensure you load the shard in shards.cr and choose a backend like Redis for pub/sub.

Cable vs Kemal's built-in WebSocket support – which should I use?

Cable is better for ActionCable compatibility and multi-backend flexibility, while Kemal's WebSocket is simpler for basic, framework-native real-time features. Cable excels if you need Rails-like APIs or plan to migrate from Rails, but Kemal might suffice for lightweight, Kemal-only projects.

Does Cable support authentication with JWT tokens?

Yes, Cable supports token-based authentication via the connection class, where you can decode JWT tokens in the connect method, as shown in the example using UserToken.decode_user_id. This allows secure identification and user instance management.

Can I use Cable without Redis for production?

While possible with backends like NATS or Postgres, the README notes these alternatives may need work before production use, so Redis is recommended for stability. Evaluate your backend choice carefully and test thoroughly if opting for non-Redis options.

How do I handle errors in Cable with a service like Bugsnag?

Configure the on_error hook in cable.cr to report exceptions to Bugsnag, as demonstrated in the README's error handling section. This allows custom logging and integration with third-party monitoring tools for better debugging.

Is Cable ready for high-traffic real-time applications?

Cable can scale with robust backends like Redis, but performance depends on your infrastructure and backend choice. The high logging overhead and experimental alternate backends might require optimization for very high traffic scenarios.

How to migrate from Rails ActionCable to Cable in Crystal?

Keep the same ActionCable JavaScript client, replace the Rails server with Cable configured in Crystal, and port channel logic using Cable's similar API. The README's compatibility ensures minimal frontend changes, but backend code must be adapted to Crystal syntax.

Cable — ActionCable WebSocket Server

What is Cable?

Cable is a WebSocket server library for the Crystal programming language that enables real-time, bidirectional communication between server and clients. It solves the problem of adding live features like chat, notifications, or updates to Crystal web applications by providing a server-side implementation fully compatible with the ActionCable JavaScript client.

Target Audience

Crystal developers building web applications that require real-time features, especially those transitioning from Ruby on Rails or seeking an ActionCable-like experience in Crystal.

Value Proposition

Developers choose Cable because it offers 100% compatibility with the widely-used ActionCable JS client, eliminating the need for custom client-side code, and provides a flexible, multi-backend architecture that integrates smoothly with existing Crystal web frameworks.

It's like ActionCable (100% compatible with JS Client), but you know, for Crystal

Use Cases

Best For

Adding real-time chat functionality to a Crystal web application
Implementing live notifications or activity feeds in Lucky framework projects
Building collaborative editing features with WebSockets in Crystal
Migrating a Rails application with ActionCable to Crystal while keeping the frontend unchanged
Creating real-time dashboards or monitoring tools with Crystal backend
Developing multiplayer game backends requiring persistent connections

Not Ideal For

Projects not using the Crystal programming language, as it's language-specific and lacks cross-platform support.
Teams requiring out-of-the-box production readiness for all backend options, since alternatives like NATS or Postgres may need additional work before deployment.
Applications needing non-ActionCable WebSocket protocols, due to its tight coupling with the ActionCable JavaScript client.
Environments with strict logging cost constraints, as default settings produce high-volume logs that require manual tuning to reduce overhead.

Pros & Cons

Pros

ActionCable JS Compatibility

Works 100% with the standard ActionCable JavaScript client, eliminating the need for custom frontend code, as highlighted in the README's seamless integration examples.

Flexible Backend Support

Supports multiple pub/sub backends including Redis, NATS, PostgreSQL, and AMQP, allowing developers to choose based on existing infrastructure, though some are experimental.

Framework Agnostic Design

Can be integrated with any Crystal web framework like Lucky or Kemal, providing versatility without locking users into a specific ecosystem.

Robust Connection Management

Offers identified connections and owned user instances, simplifying authentication and state handling, as demonstrated in the connection class with user token decoding.

Configurable Error Handling

Includes hooks for error reporting to third-party services like Bugsnag, enabling easy monitoring integration, as shown in the configuration examples.

Cons

Incomplete Backend Maturity

Alternate backends such as NATS, Postgres, and AMQP are flagged as potentially needing work before production use, limiting reliability for non-Redis setups.

Missing stream_for Feature

Lacks support for ActionCable's `stream_for` helper, requiring manual stream naming, which the README admits in the ChatChannel example.

High Logging Overhead

Default logging produces high volume, potentially increasing costs, and the README warns users to tune levels to 'warn' for critical logs only.

Complex Initial Setup

Requires detailed configuration including middleware placement, backend selection, and error handler setup, which can be daunting for new adopters.

Frequently Asked Questions

What is Cable?

Target Audience

Crystal developers building web applications that require real-time features, especially those transitioning from Ruby on Rails or seeking an ActionCable-like experience in Crystal.

Value Proposition

Use Cases

Best For

Adding real-time chat functionality to a Crystal web application
Implementing live notifications or activity feeds in Lucky framework projects
Building collaborative editing features with WebSockets in Crystal
Migrating a Rails application with ActionCable to Crystal while keeping the frontend unchanged
Creating real-time dashboards or monitoring tools with Crystal backend
Developing multiplayer game backends requiring persistent connections

Not Ideal For

Projects not using the Crystal programming language, as it's language-specific and lacks cross-platform support.
Teams requiring out-of-the-box production readiness for all backend options, since alternatives like NATS or Postgres may need additional work before deployment.
Applications needing non-ActionCable WebSocket protocols, due to its tight coupling with the ActionCable JavaScript client.
Environments with strict logging cost constraints, as default settings produce high-volume logs that require manual tuning to reduce overhead.

Pros & Cons

Pros

ActionCable JS Compatibility

Works 100% with the standard ActionCable JavaScript client, eliminating the need for custom frontend code, as highlighted in the README's seamless integration examples.

Flexible Backend Support

Supports multiple pub/sub backends including Redis, NATS, PostgreSQL, and AMQP, allowing developers to choose based on existing infrastructure, though some are experimental.

Framework Agnostic Design

Can be integrated with any Crystal web framework like Lucky or Kemal, providing versatility without locking users into a specific ecosystem.

Robust Connection Management

Offers identified connections and owned user instances, simplifying authentication and state handling, as demonstrated in the connection class with user token decoding.

Configurable Error Handling

Includes hooks for error reporting to third-party services like Bugsnag, enabling easy monitoring integration, as shown in the configuration examples.

Cons

Incomplete Backend Maturity

Alternate backends such as NATS, Postgres, and AMQP are flagged as potentially needing work before production use, limiting reliability for non-Redis setups.

Missing stream_for Feature

Lacks support for ActionCable's `stream_for` helper, requiring manual stream naming, which the README admits in the ChatChannel example.

High Logging Overhead

Default logging produces high volume, potentially increasing costs, and the README warns users to tune levels to 'warn' for critical logs only.

Complex Initial Setup

Requires detailed configuration including middleware placement, backend selection, and error handler setup, which can be daunting for new adopters.

Frequently Asked Questions

Cable

What is Cable?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

Cable

What is Cable?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?