Getting started

First, install mara with:

pip install mara

See installation for more options and details.

A minimal service

A minimal Mara service looks something like this:

from mara import App, events
from mara.servers.socket import SocketServer

app = App()
app.add_server(SocketServer(host="127.0.0.1", port=9000))

@app.on(events.Receive)
async def echo(event: events.Receive):
    event.connection.write(event.data)

app.run()

Save this as echo.py and run it using python:

$ python echo.py
Server listening: Socket 127.0.0.1:9000

Now connect to telnet://127.0.0.1:9000 and anything you enter will be sent back to you - you have built a simple echo server.

Lets look at the code in more detail:

1. First we import App and create an instance of it.

   This app will be at the core of everything we do with Mara; it manages settings, servers, and handles events.

2. Next we define and add our SocketServer.

   There are different types of server, but this one is the simplest - it deals with raw bytes. If we wanted to run additional servers on other ports, we would define and add them here.

3. Next we add an event handler, echo(...).

   We define an async function which accepts a single argument, event, and then use the @app.on decorator to register it with the app.

4. When an event of the type Receive is triggered, the echo function will be called with the current event object as the only argument.

   The event object contains all the relevant information about that event - in this case the event.connection and event.data.

5. We write the received data back to the connection with event.connection.write(...).

   The event.connection attribute is an instance of SocketConnection - our end of a specific connection. This provides the write() method to send data, and we just send back the raw data we received.

6. Lastly we call the app.run() method.

   This starts the app’s asyncio loop and runs the registered servers.