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Broker

Module pydobotlab.broker. A broker is a local TCP server that owns serial ports and relays commands from several Magician instances, including instances in other processes. Magician connects through a running broker. When the control panel is installed, it raises by default when none is running. The control panel starts a broker automatically. The wire protocol is described in The DobotBroker.

Member Description
DobotBroker TCP broker for serial ports.
DobotBroker.start Start serving.
DobotBroker.stop Stop serving, disconnect clients, and close all ports.
DobotBroker.attach Open a port and manage it.
DobotBroker.detach Close a managed port.
DobotBroker.attached_ports List the managed ports.
DobotBroker.client_count Number of connected clients.
is_broker_reachable Whether a broker accepts connections.
list_broker_ports List the ports of a running broker.

DobotBroker

class pydobotlab.broker.DobotBroker(host=None, port=None)

TCP broker for serial ports. A port that a client requests and that is not attached is opened on demand and closed when its last client disconnects. Ports opened with attach stay open until detach or stop.

Parameters

Name Type Description
host str or None, default None Address to listen on. None uses the configured default, "127.0.0.1" unless changed.
port int or None, default None TCP port. None uses the configured default, 8765 unless changed. 0 selects a free port.

Attributes

Name Type Description
host str Address to listen on.
port int TCP port. After start, the port in use.

Notes

DobotBroker is a context manager. Entering the block calls start and returns the broker; leaving it calls stop.

Example

from pydobotlab.broker import DobotBroker

with DobotBroker() as broker:
    broker.attach("COM3")
    input("Broker running. Press Enter to stop.")

DobotBroker.start

DobotBroker.start() -> None

Start serving on a background thread. Has no effect if the broker is already running.

Raises

  • OSError: the address is already in use.

DobotBroker.stop

DobotBroker.stop() -> None

Stop serving and close all attached ports. Connected clients are disconnected without waiting for them; their next command raises DobotConnectionError.

DobotBroker.attach

DobotBroker.attach(port, *, baudrate=None, timeout=None) -> SerialTransport

Open port and manage it until detach or stop. Returns the existing transport if the port is already attached.

Parameters

Name Type Description
port str Serial port.
baudrate int or None, default None Serial baud rate. None uses the configured default, as for Magician.
timeout float or None, default None Read timeout per byte, seconds. None uses the configured default.

Returns SerialTransport: the open transport.

Raises

DobotBroker.detach

DobotBroker.detach(port) -> None

Close port and stop managing it. Has no effect if the port is not attached.

DobotBroker.attached_ports

DobotBroker.attached_ports() -> list[str]

Return the attached ports, sorted.

DobotBroker.client_count

DobotBroker.client_count() -> int

Return the number of clients connected to an arm through the broker.

is_broker_reachable

pydobotlab.broker.is_broker_reachable(host=None, port=None, timeout=None) -> bool

Return whether a broker accepts connections at host:port. A result is reused for a short time.

Parameters

Name Type Description
host str or None, default None Broker host. None uses the configured default.
port int or None, default None Broker TCP port. None uses the configured default.
timeout float or None, default None Connection timeout, seconds. None uses the configured default, 0.15 unless changed.

list_broker_ports

pydobotlab.broker.list_broker_ports(host=None, port=None, timeout=None) -> list[str]

Return the ports attached to a running broker.

Parameters

Name Type Description
host str or None, default None Broker host. None uses the configured default.
port int or None, default None Broker TCP port. None uses the configured default.
timeout float or None, default None Socket timeout, seconds. None uses the configured default, 1.0 unless changed.

Raises

  • OSError: no broker is reachable.