mirror of
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110 lines
2.1 KiB
Markdown
110 lines
2.1 KiB
Markdown
---
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layout: default
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---
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# Broker
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The broker provides pub/sub messaging for Go Micro services.
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## Features
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- Publish messages to topics
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- Subscribe to topics
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- Multiple broker implementations
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## Implementations
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Supported brokers include:
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- HTTP (default)
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- NATS (`go-micro.dev/v5/broker/nats`)
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- RabbitMQ (`go-micro.dev/v5/broker/rabbitmq`)
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- Memory (`go-micro.dev/v5/broker/memory`)
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Plugins are scoped under `go-micro.dev/v5/broker/<plugin>`.
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Configure the broker in code or via environment variables.
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## Example Usage
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Here's how to use the broker in your Go Micro service:
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```go
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package main
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import (
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"go-micro.dev/v5"
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"go-micro.dev/v5/broker"
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"log"
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)
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func main() {
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service := micro.NewService()
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service.Init()
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// Publish a message
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if err := broker.Publish("topic", &broker.Message{Body: []byte("hello world")}); err != nil {
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log.Fatal(err)
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}
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// Subscribe to a topic
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_, err := broker.Subscribe("topic", func(p broker.Event) error {
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log.Printf("Received message: %s", string(p.Message().Body))
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return nil
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})
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if err != nil {
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log.Fatal(err)
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}
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// Run the service
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if err := service.Run(); err != nil {
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log.Fatal(err)
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}
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}
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```
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## Configure a specific broker in code
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NATS:
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```go
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import (
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"go-micro.dev/v5"
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bnats "go-micro.dev/v5/broker/nats"
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)
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func main() {
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b := bnats.NewNatsBroker()
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svc := micro.NewService(micro.Broker(b))
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svc.Init()
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svc.Run()
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}
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```
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RabbitMQ:
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```go
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import (
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"go-micro.dev/v5"
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"go-micro.dev/v5/broker/rabbitmq"
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)
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func main() {
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b := rabbitmq.NewBroker()
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svc := micro.NewService(micro.Broker(b))
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svc.Init()
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svc.Run()
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}
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```
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## Configure via environment
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Using the built-in configuration flags/env vars (no code changes):
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```
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MICRO_BROKER=nats MICRO_BROKER_ADDRESS=nats://127.0.0.1:4222 micro server
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```
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Common variables:
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- `MICRO_BROKER`: selects the broker implementation (`http`, `nats`, `rabbitmq`, `memory`).
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- `MICRO_BROKER_ADDRESS`: comma-separated list of broker addresses.
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Notes:
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- NATS addresses should be prefixed with `nats://`.
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- RabbitMQ addresses typically use `amqp://user:pass@host:5672`.
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