@@ -299,9 +299,150 @@ The rebroadcast will be received by all connected clients, _including_ the clien
See the [rails/actioncable-examples](https://github.com/rails/actioncable-examples) repository for a full example of how to setup Action Cable in a Rails app, and how to add channels.
## Download and installation
## Configuration
The latest version of Action Cable can be installed with RubyGems:
Action Cable has three required configurations: a subscription adapter, allowed request origins, and the cable server URL (which can optionally be set on the client side).
### Redis
By default, `ActionCable::Server::Base` will look for a configuration file in `Rails.root.join('config/cable.yml')`.
This file must specify an adapter and a URL for each Rails environment. It may use the following format:
```yaml
production:&production
adapter:redis
url:redis://10.10.3.153:6381
development:&development
adapter:redis
url:redis://localhost:6379
test:*development
```
You can also change the location of the Action Cable config file in a Rails initializer with something like:
Action Cable will only accept requests from specified origins, which are passed to the server config as an array. The origins can be instances of strings or regular expressions, against which a check for match will be performed.
The second option is to pass the server URL through the `action_cable_meta_tag` in your layout.
This uses a URL or path typically set via `config.action_cable.url` in the environment configuration files, or defaults to "/cable".
This method is especially useful if your WebSocket URL might change between environments. If you host your production server via https, you will need to use the wss scheme
for your Action Cable server, but development might remain http and use the ws scheme. You might use localhost in development and your
domain in production.
In any case, to vary the WebSocket URL between environments, add the following configuration to each environment:
```ruby
config.action_cable.url="ws://example.com:28080"
```
Then add the following line to your layout before your JavaScript tag:
```erb
<%=action_cable_meta_tag%>
```
And finally, create your consumer like so:
```coffeescript
App.cable=ActionCable.createConsumer()
```
### Other Configurations
The other common option to configure is the log tags applied to the per-connection logger. Here's an example that uses the user account id if available, else "no-account" while tagging:
For a full list of all configuration options, see the `ActionCable::Server::Configuration` class.
Also note that your server must provide at least the same number of database connections as you have workers. The default worker pool is set to 4, so that means you have to make at least that available. You can change that in `config/database.yml` through the `pool` attribute.
## Running the cable server
### Standalone
The cable server(s) is separated from your normal application server. It's still a Rack application, but it is its own Rack
application. The recommended basic setup is as follows:
Then you start the server using a binstub in bin/cable ala:
```sh
#!/bin/bash
bundle exec puma -p 28080 cable/config.ru
```
The above will start a cable server on port 28080.
### In app
If you are using a server that supports the [Rack socket hijacking API](http://www.rubydoc.info/github/rack/rack/file/SPEC#Hijacking), Action Cable can run alongside your Rails application. For example, to listen for WebSocket requests on `/websocket`, specify that path to `config.action_cable.mount_path`:
```ruby
# config/application.rb
classApplication<Rails::Application
config.action_cable.mount_path='/websocket'
end
```
For every instance of your server you create and for every worker your server spawns, you will also have a new instance of Action Cable, but the use of Redis keeps messages synced across connections.
### Notes
Beware that currently, the cable server will _not_ auto-reload any changes in the framework. As we've discussed, long-running cable connections mean long-running objects. We don't yet have a way of reloading the classes of those objects in a safe manner. So when you change your channels, or the model your channels use, you must restart the cable server.
We'll get all this abstracted properly when the framework is integrated into Rails.
The WebSocket server doesn't have access to the session, but it has access to the cookies. This can be used when you need to handle authentication. You can see one way of doing that with Devise in this [article](http://www.rubytutorial.io/actioncable-devise-authentication).
## Dependencies
Action Cable provides a subscription adapter interface to process its pubsub internals. By default, asynchronous, inline, PostgreSQL, evented Redis, and non-evented Redis adapters are included. The default adapter in new Rails applications is the asynchronous (`async`) adapter. To create your own adapter, you can look at `ActionCable::SubscriptionAdapter::Base` for all methods that must be implemented, and any of the adapters included within Action Cable as example implementations.
The Ruby side of things is built on top of [websocket-driver](https://github.com/faye/websocket-driver-ruby), [nio4r](https://github.com/celluloid/nio4r), and [concurrent-ruby](https://github.com/ruby-concurrency/concurrent-ruby).
For convenience `class_attribute` also defines an instance predicate which is the double negation of what the instance reader returns. In the examples above it would be called `x?`.
