# Sockets

## Introduction

Socket structs are the objects that are stored in memory per connection and retain the persistent communication.

Sockets define one public method on\_connect which can contain functionality that should run when a user connects, including authentication. This methods should return a Bool. If `true` the socket will remain open. If `false` the socket will be closed immediately.

An `Amber::WebSockets::ClientSocket` instance has both `cookies` and `session` getters and are available from within the `on_connect` method.

Socket structs also map topics to the channels they will connect with.

## Example Usage

A socket can be generated by calling `amber g socket Chat`

```ruby
struct ChatSocket < Amber::WebSockets::ClientSocket
  channel "chat_room:*", ChatRoomChannel

  def on_connect
    # self.session and self.cookies available here
    # do authentication here like
    # !self.session[:user_id].nil?

    # returning true accept all connections
    true
  end
end
```

## Add a new Route

A new route needs to be added so that a handshake can be established with the server. Notice how after `\chat`, the struct `ChatSocket` that was created 
above is mapped to that route.

```ruby
Amber::Server.configure do |app|
  pipeline :web do
    # pipelines...
  end

  routes :web do
    # other routes,,,
    websocket "/chat", ChatSocket
  end
end
```

## Send messages from controllers \(or anywhere else\)

`Amber::WebSockets::ClientSocket` provides a public class method `broadcast` for publishing messages to all subscribers of a topic from within controllers or anywhere else in your application.

```ruby
class HomeController < ApplicationController
  def index
    ChatSocket.broadcast("message", "chat_room:123", "message_new", {"message" => "A new visitor!"})
    render("index.slang")
  end
end
```