lomond 0.2.3

Websocket Client Library

Dataplicity Lomond

Tranquil WebSockets for Python.

Lomond is a Websocket client which turns a websocket connection in to an orderly stream of events. No threads or callbacks necessary.

• Documentation

• GitHub Repository

• Blog

How to Use

To connect to a "ws:" or "wss:" WebSocket URL, construct a lomond.WebSocket object then iterate over it. This will yield an event object for each step in the connection process and for any data sent by the server.

You will receive a Binary or Text event when the server sends you a message. You may send a message with the send_binary or send_text methods.

Example

The following is a silly example that connects to a websocket server (in this case a public echo server), and sends a string of text every 5 seconds.

from lomond import WebSocket


websocket = WebSocket('wss://echo.websocket.org')

for event in websocket:
    if event.name == 'poll':
        websocket.send_text('Hello, World')
    elif event.name == 'text':
        print(event.text)

Events

A successful websocket connection will result in a series of events such as the following:

┌──────────────────────┐
│      Connecting      │     Contacting server
└──────────────────────┘
           │
           ▼
┌──────────────────────┐     Connected to server (but
│      Connected       │     not yet sent data)
└──────────────────────┘
           │
           ▼
┌──────────────────────┐     Negotiated Websocket
│        Ready         │     handshake
└──────────────────────┘
           │  ┌───────────┐
           │  │           │
           ▼  ▼           │
┌──────────────────────┐  │  Send and receive
│ Binary / Text / Poll │──┘  application data
└──────────────────────┘
           │
           ▼
┌──────────────────────┐     Websocket close
│        Closed        │     handshake
└──────────────────────┘
           │
           ▼
┌──────────────────────┐
│     Disconnected     │     Disconnected TCP/IP
└──────────────────────┘     connection to server