Usage

Using MSL-Network requires a sequence of 3 steps:

Start the Network Manager
Start a Service on the Network Manager
Connect to the Network Manager as a Client

Start the Network Manager

The first thing to do is to start the Network Manager. There are 3 ways to do this.

From a terminal run:
msl-network start
Running this command will automatically perform the following default actions:
create a private 2048-bit, RSA key

create a self-signed certificate using the private key

create an SQLite database to store information that is used by the Network Manager

start the Network Manager on the default port using the TLS protocol

no authentication is required for Client's and Service's to connect to the Manager
You can override the default actions, for example, use Elliptic-Curve Cryptography rather than RSA or only allow certain users to be able to connect to the Manager. For more details refer to the help that is available from the command line
msl-network --help msl-network start --help
Call run_forever() in a script.
Call run_services() in a script. This method also starts the Service's immediately after the Manager starts.

Start a Service on the Network Manager

In order to create a new Service just create a class that is a subclass of Service and call the start() method.

BasicMath Service

For example, the BasicMath Service is a simple (and terribly inefficient) Service that performs some basic math operations and it is included with MSL-Network.

To start the BasicMath Service on the Manager that is running on the same computer, run the following command in a terminal

python -c "from msl.examples.network import BasicMath; BasicMath().start()"

Note

The reason for adding the time.sleep() functions in the BasicMath Service will become evident when discussing Asynchronous Programming.

Connect to the Network Manager as a Client

Now that there is a BasicMath Service running on the Network Manager (which are both running on the same computer that the Client will be), we can connect() to the Network Manager

>>> from msl.network import connect
>>> cxn = connect(name='MyClient')

establish a link with the BasicMath Service

>>> bm = cxn.link('BasicMath')

and send a request to the BasicMath Service

>>> bm.add(1, 2)
3

See the Asynchronous Programming section for an example on how to send requests asynchronously.

To find out what devices are currently connected to the Manager, execute

>>> print(cxn.identities(as_string=True))
Manager[localhost:1875]
  attributes:
    identity() -> dict
    link(service: str) -> bool
  language: Python 3.9.7
  os: Windows 10 AMD64
Clients [1]:
  MyClient[localhost:63818]
    language: Python 3.9.7
    os: Windows 10 AMD64
Services [1]:
  BasicMath[localhost:63815]
    attributes:
      add(x: Union[int, float], y: Union[int, float]) -> Union[int, float]
      divide(x: Union[int, float], y: Union[int, float]) -> Union[int, float]
      ensure_positive(x: Union[int, float]) -> bool
      euler() -> 2.718281828459045
      multiply(x: Union[int, float], y: Union[int, float]) -> Union[int, float]
      pi() -> 3.141592653589793
      power(x: Union[int, float], n=2) -> Union[int, float]
      set_logging_level(level: Union[str, int]) -> bool
      subtract(x: Union[int, float], y: Union[int, float]) -> Union[int, float]
    language: Python 3.9.7
    max_clients: -1
    os: Windows 10 AMD64

If as_string=False, which is the default boolean value, then the returned value would be a dict, rather than a str, containing the same information.

To disconnect from the Manager, execute

>>> cxn.disconnect()

If you only wanted to connect to the BasicMath Service (and no other Services on the Manager) then you could create a LinkedClient

>>> from msl.network import LinkedClient
>>> bm = LinkedClient('BasicMath')
>>> bm.add(1, 2)
3
>>> bm.disconnect()