https://github.com/borud/broker

Trivial message broker
https://github.com/borud/broker

broker go golang golang-library pubsub

Last synced: 10 days ago
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Trivial message broker

• Host: GitHub
• URL: https://github.com/borud/broker
• Owner: borud
• License: apache-2.0
• Created: 2020-12-12T13:00:21.000Z (almost 4 years ago)
• Default Branch: main
• Last Pushed: 2024-01-25T18:53:37.000Z (9 months ago)
• Last Synced: 2024-08-01T00:43:09.014Z (3 months ago)
• Topics: broker, go, golang, golang-library, pubsub
• Language: Go
• Homepage:
• Size: 44.9 KB
• Stars: 5
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Broker - a minimal pubsub

[![GoDoc Reference](https://godoc.org/github.com/borud/broker?status.svg)](http://godoc.org/github.com/borud/broker)

pubsub is a very small library for implementing the simplest possible

publish-subscribe mechanism for Go using channels.

## Usage

    import "github.com/borud/broker"

### Creating a new broker

    broker := New(Config{

        DownStreamChanLen:  100,

        PublishChanLen:     100,

        SubscribeChanLen:   10,

        UnsubscribeChanLen: 10,

        DeliveryTimeout:    10*time.Millisecond,

    })

The configuration options are

- `DownStreamChanLen` is the length of the channel used to send messages to the subscriber.

- `PublishChanLen` is the length of the incoming channel used by `Publish()`

- `SubscribeChanLen` is the length of the channel that accepts `Subscribe()` requests

- `UnsubscribeChanLen` is the length of the channel that accepts unsubscribe requests.

- `DeliveryTimeout` is the timeout before giving up delivering a message to a subscriber

### Subscribe to topic or topic prefix

  

    sub, err := broker.Subscribe("/foo/bar")

### Fetch messages from subscription

    for msg := range sub.Messages() {

        log.Printf("topic = '%s', message = '%+v'", msg.Topic, msg.Payload)

    }

### Publish message to broker with timeout

    err := broker.Publish("/foo", "some payload", 300 * time.Millisecond)

### Cancel a subscription

    err := sub.Cancel()

### Shut down broker

    broker.Shutdown()

### Topics

Topics are entirely dynamic, meaning that a topic exists if there are

subscribers listening to it.  If a message is published to a topic

that has no subscribers, nothing will happen and the message is

silently discarded.

Topics are hierarchical and look like filesyste paths and matching is

by path prefix.

    /house/bedroom/light

    /house/bedroom/temp

    /house/kitchen/light

    /house/kitchen/temp

    /house/kitchen/humidity

Your subscription can be for any prefix of the path, including the

full path.  You will receive all messages that match your prefix.  So

for instance if you subscribe to `/house/kitchen` you will get all

messages sent to

    /house/kitchen

    /house/kitchen/light

    /house/kitchen/temp

    /house/kitchen/humidity

If you subscribe to `/house/kitchen/temp` you will only get messages

sent to this single topic since it has no children.

At this time **no** wildcard matching is supported.

## Logging

Libraries shouldn't emit log messages, but sometimes you might want to output log messages if you suspect something funny is going on.  You can register your own logger via the `Config` type, like this:

    b := New(Config{Logger: log.Printf})

The `Logger` is of type `Printfer` (a Printf'er to use the naming conventions of go), which looks like this:

    func(string, ...interface{})

...which happens to be the signature of `log.Printf` (but not `fmt.Printf`).