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core.messaging.message

Message Objects​

@dataclass_json

@dataclass(frozen=True, kw_only=True)
class Message(abc.ABC)

Base class for all messages.

A message, besides its actual data, consists mainly of information from where it came and where it should go.

This class also offers a useful decorator to easily declare new messages, like in the following example::

@Message.define("msg/command") class MyCommand(Command): some_number: int = 0

Attributes:

  • name - The name of the message.
  • origin - The initial source component of the message.
  • sender - The component from where the message came from.
  • target - Where the message should go to.
  • hops - A list of components the message was sent through.
  • trace - A unique trace identifying messages that logically belong together.
  • api_key - An optional API key to access protected resources.

message_name​

@staticmethod
def message_name() -> MessageName

Retrieves the name of the message type on a message class basis.

is_protected​

@staticmethod
def is_protected() -> bool

Whether this message is protected and thus requires an API key.

define​

@staticmethod
def define(name: str, is_protected: bool = False)

Defines a new message.

The decorator takes care of wrapping the new class as a dataclass, passing the correct message name to its constructor. It also registers the new message type in the global MessageTypesCatalog.

Examples::

@Message.define("msg/command") class MyCommand(Command): some_number: int = 0

Arguments:

  • name - The name of the message.
  • is_protected - Whether the message requires an API key.

payload​

@property
def payload() -> MessagePayload

The message payload.