broker.go

// MIT License
//
// Copyright (c) 2020 Lack
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

// Package broker is an interface used for asynchronous messaging
package broker

import "context"

// Broker is an interface used for asynchronous messaging.
type Broker interface {
	Init(...Option) error
	Options() Options
	Address() string
	Connect() error
	Disconnect() error
	Publish(ctx context.Context, topic string, m *Message, opts ...PublishOption) error
	Subscribe(topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
	String() string
}

// Handler is used to process messages via a subscription of a topic.
// The handler is passed a publication interface which contains the
// message and optional Ack method to acknowledge receipt of the message.
type Handler func(Event) error

type Message struct {
	Header map[string]string
	Body   []byte
}

// Event is given to a subscription handler for processing
type Event interface {
	Topic() string
	Message() *Message
	Ack() error
	Error() error
}

// Subscriber is a convenience return type for the Subscribe method
type Subscriber interface {
	Options() SubscribeOptions
	Topic() string
	Unsubscribe() error
}

var (
	DefaultBroker Broker
)

func Init(opts ...Option) error {
	return DefaultBroker.Init(opts...)
}

func Connect() error {
	return DefaultBroker.Connect()
}

func Disconnect() error {
	return DefaultBroker.Disconnect()
}

func Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
	return DefaultBroker.Publish(ctx, topic, msg, opts...)
}

func Subscribe(topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
	return DefaultBroker.Subscribe(topic, handler, opts...)
}

func String() string {
	return DefaultBroker.String()
}