hvl_ccb.comm.telnet

Communication protocol for telnet. Makes use of the telnetlib library.

class TelnetCommunication(configuration)

Bases: AsyncCommunicationProtocol

Implements the Communication Protocol for telnet.

close()

Close the telnet connection unless it is not closed.

static config_cls()

Return the default configdataclass class.

Returns:

a reference to the default configdataclass class

property is_open: bool

Is the connection open?

Returns:

True for an open connection

open()

Open the telnet connection unless it is not yet opened.

read_bytes() → bytes

Read data as bytes from the telnet connection.

Returns:

data from telnet connection

Raises:

TelnetError – when connection is not open, raises an Error during the communication

write_bytes(data: bytes)

Write the data as bytes to the telnet connection.

Parameters:

data – Data to be sent.

Raises:

TelnetError – when connection is not open, raises an Error during the communication

class TelnetCommunicationConfig(terminator: bytes = b'\r\n', encoding: str = 'utf-8', encoding_error_handling: str = 'strict', wait_sec_read_text_nonempty: int | float = 0.5, default_n_attempts_read_text_nonempty: int = 10, host: str | IPv4Address | IPv6Address | None = None, port: int = 0, timeout: int | float = 0.2)

Bases: AsyncCommunicationProtocolConfig

Configuration dataclass for TelnetCommunication.

clean_values()

create_telnet() → Telnet | None

Create a telnet client :return: Opened Telnet object or None if connection is not possible

force_value(fieldname, value)

Forces a value to a dataclass field despite the class being frozen.

NOTE: you can define post_force_value method with same signature as this method to do extra processing after value has been forced on fieldname.

Parameters:

• fieldname – name of the field

• value – value to assign

host: str | IPv4Address | IPv6Address | None = None

Host to connect to can be localhost or

classmethod keys() → Sequence[str]

Returns a list of all configdataclass fields key-names.

Returns:

a list of strings containing all keys.

classmethod optional_defaults() → dict[str, object]

Returns a list of all configdataclass fields, that have a default value assigned and may be optionally specified on instantiation.

Returns:

a list of strings containing all optional keys.

port: int = 0

Port at which the host is listening

classmethod required_keys() → Sequence[str]

Returns a list of all configdataclass fields, that have no default value assigned and need to be specified on instantiation.

Returns:

a list of strings containing all required keys.

timeout: int | float = 0.2

Timeout for reading a line

exception TelnetError

Bases: OSError, CommunicationError

Telnet communication related errors.