prpc.protocol.messages¶
Logical message types definitions, encapsulating both field access and wire serialization format.
Note
Message classes are rather similar, so they could have been generated using some factory. However, generating ‘first-class’ classes without self-introspection would require really ugly hacks with exec (e.g. see collections.namedtuple). As a bonus, manual classes are IDE-friendly.
Note
namedtuple itself isn’t right as there is no sane way to ‘bind’ the first tuple argument to be constant (MessageType).
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prpc.protocol.messages.message_class(cls)¶ Decorator to register message class for deserialization.
Explicit mapping looks cleaner than __subclasses__ hacks and adds some bonus validation.
Parameters: cls – Class with (not yet registered) class-level MESSAGE_TYPE variable. Returns: Cls itself without any changes.
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prpc.protocol.messages.pack(data)¶ Convert ‘simple’ (~POD) python object to a compact byte representation.
Parameters: data – Object to pack. Returns: Byte representation of the object.
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prpc.protocol.messages.unpack(dgram)¶ Unpack byte representation of an object.
Parameters: dgram – Serialized object bytes. Returns: Unpacked object.
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class
prpc.protocol.messages.ProtocolMessage¶ Base class for protocol messages.
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classmethod
from_bytes(dgram)¶ Decode message from wire format.
Parameters: dgram – Message bytes. Returns: Decoded message.
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to_bytes()¶ Encode message to wire format.
Returns: Serialized message bytes.
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to_tuple()¶ Convert message to a tuple (with fixed field order).
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classmethod
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class
prpc.protocol.messages.HandshakeData(protocol_version, id, user_data)¶ Handshake data. Very basic for now.
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id¶ Alias for field number 1
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protocol_version¶ Alias for field number 0
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user_data¶ Alias for field number 2
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class
prpc.protocol.messages.ErrorDescription(message, cause_type, cause_message, trace)¶ Serialized exception object.
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cause_message¶ Alias for field number 2
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cause_type¶ Alias for field number 1
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message¶ Alias for field number 0
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trace¶ Alias for field number 3
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class
prpc.protocol.messages.RequestHandshake(id, args)¶ Handshake message sent by ‘connecting’ side.
Contains 1 payload field:
- args: handshake ‘arguments’ (must be HandshakeData tuple)
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class
prpc.protocol.messages.RequestCallStart(id, call_type, method, args, kwargs)¶ Message requesting a new call.
Contains 4 payload fields:
- call_type: enum value desribing call type
- method: method name
- args: positional argument list
- kwargs: keyword argument dict
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class
prpc.protocol.messages.RequestCallCancel(id)¶ Request to close remote stream on the callee side.
Has no payload.
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class
prpc.protocol.messages.RequestStreamMessage(id, data)¶ Data message containing stream message from caller.
Only 1 payload field:
- data: unserialized data (will be packed with the message itself)
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class
prpc.protocol.messages.RequestStreamClose(id)¶ Request to close remote stream on the callee side.
Has no payload.
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class
prpc.protocol.messages.ResponseHandshake(id, result, status, error)¶ Handshake call response.
Contains 3 payload fields:
- result: call return value (must be a HandshakeData tuple)
- status: call status
- error: error as ErrorDescription tuple
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class
prpc.protocol.messages.ResponseResult(id, result, status, error)¶ Regular call final response.
Has similar structure to the hanshake response, but the result isn’t limited to HandshakeData.
Contains 3 payload fields:
- result: call return value
- status: call status
- error: error as ErrorDescription tuple
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class
prpc.protocol.messages.ResponseStreamMessage(id, data)¶ Data message containing stream message from callee.
Only 1 payload field:
- data: unserialized data (will be packed with the message itself)
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class
prpc.protocol.messages.ResponseStreamClose(id)¶ Request to close stream on the calling side.
Has no payload.