AnyCable

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RPC over HTTP ​

AnyCable supports RPC communication between a real-time server and your web application over HTTP. Although the default gRPC communication is more performant and, thus, preferred, it comes with a price of additional infrastructure complexity—you have to manage a separate process/service.

AnyCable Ruby comes with a Rack middleware that implements AnyCable RPC API. You can mount it into your Rack-compatible application.

See the demo of using HTTP RPC in a Rails application.

Learn more about different RPC modes in the AnyCable documentation.

Using with Rails ​

To enable HTTP RPC in your Rails application, all you need is to configure the http_rpc or http_rpc_mount_path parameter. For example, in your config/anycable.yml:

yml
development:
  http_rpc: true # uses default /_anycable path

production:
  http_rpc_mount_path: "/__some_other_anycable_path"

That's it! Now configure your AnyCable server to perform RPC over HTTP at your mount path (e.g., /_anycable).

NOTE: If you don't use AnyCable gRPC server in any environment, you can avoid installing gRPC dependencies by using the anycable-rails-core gem instead of anycable-rails.

Security ​

You can (and MUST in production) protect your HTTP RPC server with basic token-based authorization. To do so, you need to set the http_rpc_secret parameter (in YAML or via the ANYCABLE_HTTP_RPC_SECRET environment variable). Don't forget to set the same value in your WebSocket server configuration.

Considerations ​

  • Performance. HTTP/1 has a higher overhead than HTTP/2 used by gRPC, so you should expect a higher latency and lower throughput. Keep this in mind when choosing between HTTP RPC and gRPC.

  • Shared web server resources. Rails applications have a limited HTTP concurrency (based on the total number of threads used by a web server, such as Puma), serving both regular HTTP requests and AnyCable RPC requests can result into a race for shared resources, and, in the worst case, longer request queuing times for user-facing HTTP operations.

  • Scalability. It's not possible to scale AnyCable RPC requests separately from the main web application. If you need to scale AnyCable RPC requests independently, you should use gRPC.

Using with Rack ​

You can mount AnyCable HTTP RPC server into your Rack application using the Rack Builder interface:

ruby
Rack::Builder.new do
  map "/anycable" do
    run AnyCable::HTTPRC::Server.new
  end
end