websocket.nvim

Installation

lazy.nvim

{
    "samsze0/websocket.nvim",
    dependencies = {
        "samsze0/utils.nvim"
    }
}

Client:

local WebsocketClient = require("websocket.client").WebsocketClient

local client = WebsocketClient.new({
    connect_addr = "ws://localhost:8080",
    on_message = function(self, message)
        print("Received message: " .. message)
    end,
    on_connect = function(self)
        print("Connected")
    end,
    on_disconnect = function(self)
        print("Disconnected")
    end
})

client:try_connect()

-- Schedule to run in 2 seconds
vim.defer_fn(function()
  client:try_send_data("Hello server")
end, 2000)

-- Schedule to run in 5 seconds
vim.defer_fn(function()
  client:try_disconnect()
end, 5000)

Server:

local WebsocketServer = require("websocket.server").WebsocketServer

local server = WebsocketServer.new({
    host = "localhost",
    port = 12001,
    on_message = function(self, client_id, message)
        print("Server received message from client " .. client_id .. ": " .. message)
        self:try_send_data_to_client(client_id, "Reply from server")
    end,
    on_client_connect = function(self, client_id)
        print("Client " .. client_id .. " connected")
    end,
    on_client_disconnect = function(self, client_id)
        print("Client " .. client_id .. " disconnected")
    end,
    on_error = function(self, err)
        print("Server encountered error", vim.inspect(err))
    end,
})

server:try_start()

How it works

Because currently there is no decent Lua/libuv implementations of web servers, so I decided to base this plugin on the Tungstenite crate for the majority of the heavy lifting (i.e. the handling of the websocket protocol). The communication between Neovim/Lua and Rust is facilitated by Rust's FFI (nvim-oxi in combination with mlua). Here is an outline of how it works:

1. Neovim/Lua imports the Rust functions (compiled into a dynamic lib) via require
2. Neovim/Lua calls the Rust functions to start the websocket server
3. Neovim/Lua stores the callbacks (e.g. on_message, on_connected, on_disconnected) as global objects, waiting for the Rust code to pull from using mlua

License

MIT