Proposal: Add more semantics for message

[fgieseke]

Background

Messagingsystems: RabbitMq / Kafka

Proposal

Add semantics
Kafka: message_topic, message_offset
RabbitMQ: message_routingkey, message_queue, message_exchange

[whiskeysierra]

message_topic
message_queue

That's already covered by message_bus.destination.

message_exchange

What would that be? Hostname? peer.hostname? peer.address?

message_routingkey

What would be an example?