messaging

Documentation

Index

• Constants
• type MessageClient
  • func NewMessageClient(msgConfig types.MessageBusConfig) (MessageClient, error)

Constants

const (
	// MQTT messaging implementation
	MQTT = "mqtt"

	// Redis Pub/Sub messaging implementation
	Redis = "redis"

	// NatsCore implementation
	NatsCore = "nats-core"

	// NatsJetStream implementation
	NatsJetStream = "nats-jetstream"
)

Types

type MessageClient

type MessageClient interface {
	// Connect to messaging host specified in MessageBus config
	// returns error if not able to connect
	Connect() error

	// Publish is to send message to the message bus
	// the message contains data payload to send to the message queue
	Publish(message types.MessageEnvelope, topic string) error

	// Subscribe is to receive messages from topic channels
	// if message does not require a topic, then use empty string ("") for topic
	// the topic channel contains subscribed message channel and topic to associate with it
	// the channel is used for multiple threads of subscribers for 1 publisher (1-to-many)
	// the messageErrors channel returns the message errors from the caller
	// since subscriber works in asynchronous fashion
	// the function returns error for any subscribe error
	Subscribe(topics []types.TopicChannel, messageErrors chan error) error

	// Request publishes a request containing a RequestID to the specified topic,
	// then subscribes to a response topic which contains the RequestID. Once the response is received, the
	// response topic is unsubscribed and the response data is returned. If no response is received within
	// the timeout period, a timed out  error returned.
	Request(message types.MessageEnvelope, requestTopic string, responseTopicPrefix string, timeout time.Duration) (*types.MessageEnvelope, error)

	// Unsubscribe to unsubscribe from the specified topics.
	Unsubscribe(topics ...string) error

	// Disconnect is to close all connections on the message bus
	// and TopicChannel will also be closed
	Disconnect() error
}

MessageClient is the messaging interface for publisher-subscriber pattern

func NewMessageClient

func NewMessageClient(msgConfig types.MessageBusConfig) (MessageClient, error)

NewMessageClient is a factory function to instantiate different message client depending on the "Type" from the configuration