# Functions
NewMessageEnvelope creates a new MessageEnvelope for the specified payload with attributes from the specified context.
# Structs
HostInfo is the URL information of the host as the following scheme: <Protocol>://<Host>:<Port>.
MessageBusConfig defines the messaging information need to connect to the message bus in a publish-subscribe pattern.
MessageEnvelope is the data structure for messages.
TopicChannel is the data structure for subscriber.