# WebSock
[](https://github.com/phoenixframework/websock/actions)
[](https://hexdocs.pm/websock)
[](https://hex.pm/packages/websock)
WebSock is a specification for apps to service WebSocket connections; you can think
of it as 'Plug for WebSockets'. WebSock abstracts WebSocket support from servers such as
[Bandit](https://github.com/mtrudel/bandit/) or [Cowboy](https://github.com/ninenines/cowboy)
and exposes a generic WebSocket API to applications. WebSocket-aware
applications such as Phoenix can then be hosted within a supported web server
simply by defining conformance to the `WebSock` behaviour, in the same manner as
how Plug conformance allows their HTTP aspects to be hosted within an arbitrary
web server.
This package defines the `WebSock` behaviour which describes the functions that
an application such as Phoenix must implement in order to be WebSock compliant; it
is roughly the equivalent of the `Plug` interface, but for WebSocket
connections. It is commonly used in conjunction with the
[websock_adapter](https://hex.pm/packages/websock_adapter) package which
defines concrete adapters on top of [Bandit](https://github.com/mtrudel/bandit/)
and [Cowboy](https://github.com/ninenines/cowboy); the two packages are separate
to allow for servers which directly expose `WebSock` support to depend on just
the behaviour. Users will almost always want to depend on
[websock_adapter](https://hex.pm/packages/websock_adapter) instead of this
package.
## WebSocket Lifecycle
WebSocket connections go through a well defined lifecycle mediated by `WebSock`
and `WebSock.Adapters`:
* **This step is outside the scope of the WebSock API**. A client will
attempt to Upgrade an HTTP connection to a WebSocket connection by passing
a specific set of headers in an HTTP request. An application may choose to
determine the feasibility of such an upgrade request however it pleases
* An application will then signal an upgrade to be performed by calling
`WebSockAdpater.upgrade/4`, passing in the `Plug.Conn` to upgrade, along with
the `WebSock` compliant handler module which will handle the connection once
it is upgraded
* The underlying server will then attempt to upgrade the HTTP connection to a WebSocket connection
* Assuming the WebSocket connection is successfully negotiated, WebSock will
call `c:WebSock.init/1` on the configured handler to allow the application to perform any necessary
tasks now that the WebSocket connection is live
* WebSock will call the configured handler's `c:WebSock.handle_in/2` callback
whenever data is received from the client
* WebSock will call the configured handler's `c:WebSock.handle_info/2` callback
whenever other processes send messages to the handler process
* The `WebSock` implementation can send data to the client by returning
a `{:push,...}` tuple from any of the above `handle_*` callbacks
* At any time, `c:WebSock.terminate/2` (if implemented) may be called to indicate a close, error or
timeout condition
For more information, consult the [docs](https://hexdocs.pm/websock).
## Installation
The websock package can be installed by adding `websock` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:websock, "~> 0.5"}
]
end
```
Documentation can be found at <https://hexdocs.pm/websock>.
## License
MIT
