messaging

README

Messaging

messaging package defines Publisher, Subscriber and an aggregate Pubsub interface.

Subscriber interface defines methods used to subscribe to a message broker such as MQTT or NATS or RabbitMQ.

Publisher interface defines methods used to publish messages to a message broker such as MQTT or NATS or RabbitMQ.

Pubsub interface is composed of Publisher and Subscriber interface and can be used to send messages to as well as to receive messages from a message broker.

Documentation

Index

• Constants
• Variables
• func CreateMessage(pc *protomfx.PubConfByKeyRes, protocol, subject string, payload *[]byte) protomfx.Message
• func CreateSubject(subtopic string) (string, error)
• func ExtractSubtopic(path string) (string, error)
• type MessageHandler
• type PubSub
• type Publisher
• type Subscriber

Constants

const (
	SenMLContentType = "application/senml+json"
	CBORContentType  = "application/senml+cbor"
	JSONContentType  = "application/json"
	SenMLFormat      = "senml"
	JSONFormat       = "json"
	CBORFormat       = "cbor"
)

Variables

var (
	// ErrConnect indicates that connection to MQTT broker failed
	ErrConnect = errors.New("failed to connect to MQTT broker")

	// ErrPublishTimeout indicates that the publishing failed due to timeout.
	ErrPublishTimeout = errors.New("failed to publish due to timeout reached")

	// ErrSubscribeTimeout indicates that the subscription failed due to timeout.
	ErrSubscribeTimeout = errors.New("failed to subscribe due to timeout reached")

	// ErrUnsubscribeTimeout indicates that unsubscribe failed due to timeout.
	ErrUnsubscribeTimeout = errors.New("failed to unsubscribe due to timeout reached")

	// ErrUnsubscribeDeleteTopic indicates that unsubscribe failed because the topic was deleted.
	ErrUnsubscribeDeleteTopic = errors.New("failed to unsubscribe due to deletion of topic")

	// ErrNotSubscribed indicates that the topic is not subscribed to.
	ErrNotSubscribed = errors.New("not subscribed")

	// ErrEmptyTopic indicates the absence of topic.
	ErrEmptyTopic = errors.New("empty topic")

	// ErrMalformedSubtopic indicates that the subtopic is malformed.
	ErrMalformedSubtopic = errors.New("malformed subtopic")

	// ErrEmptyID indicates the absence of ID.
	ErrEmptyID = errors.New("empty ID")
)

Functions

func CreateMessage

func CreateMessage(pc *protomfx.PubConfByKeyRes, protocol, subject string, payload *[]byte) protomfx.Message

func CreateSubject

func CreateSubject(subtopic string) (string, error)

func ExtractSubtopic

func ExtractSubtopic(path string) (string, error)

Types

type MessageHandler

type MessageHandler interface {
	// Handle handles messages passed by underlying implementation.
	Handle(msg protomfx.Message) error

	// Cancel is used for cleanup during unsubscribing and it's optional.
	Cancel() error
}

MessageHandler represents protomfx.Message handler for Subscriber.

type PubSub

type PubSub interface {
	Publisher
	Subscriber
}

PubSub represents aggregation interface for publisher and subscriber.

type Publisher

type Publisher interface {
	// Publish publishes message to the message broker.
	Publish(msg protomfx.Message) error

	// Close gracefully closes message publisher's connection.
	Close() error
}

Publisher specifies message publishing API.

type Subscriber

type Subscriber interface {
	// Subscribe subscribes to the message stream and consumes messages.
	Subscribe(id, topic string, handler MessageHandler) error

	// Unsubscribe unsubscribes from the message stream and
	// stops consuming messages.
	Unsubscribe(id, topic string) error

	// Close gracefully closes message subscriber's connection.
	Close() error
}

Subscriber specifies message subscription API.