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Altiano Gerung
Altiano Gerung

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Cnator: channel-based subscriptions in Go

#go #opensource #eventdriven

Channels is one of those things that makes Go awesome.

I use channels quite a lot in my next open projects. One of those scenario is to model an event-driven approach.

While developing these projects, I noticed that the setup is more or less the same, so I decided to make a Go module for that.

It's called Cnator (pronounce "c-nator")

go get gitlab.com/altiano/cnator
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It has 3 methods :

  • New()
  • Subscribe(channel, subscriber)
  • Serve()

that can be use it like this

 cnator := cnator.New() channels := createChannels() // provide channel reference to each publisher producerA := NewProducerA(channels.chanA) producerB := NewProducerB(channels.chanB) producerC := NewProducerC(channels.chanC) // using cnator to subscribe to those channel events subscriberA := subscriberA{} subscriberB := subscriberB{} subscriberC := subscriberC{} cnator.Subscribe(channels.chanA, subscriberA.receiveChanA) cnator.Subscribe(channels.chanB, subscriberB.receiveChanB) cnator.Subscribe(channels.chanC, subscriberC.receiveChanC) // start watching for events cnator.Serve()
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createChannel() just initialized the channels, but you should provide your own model

func createChannels() channels { return channels{ chanA: make(chan struct{}), chanB: make(chan string), chanC: make(chan Person), } }
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the subscribers are just callback functions with a matching data type with the channels

func (s *subscriberA) receiveChanA() { fmt.Println("Subscriber A receiving") } func (s *subscriberB) receiveChanB(data string) { fmt.Println("Subscriber B receiving", data) } func (s *subscriberC) receiveChanC(data Person) { fmt.Println("Subscriber C receiving", data) }
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except for chanA that receive empty struct{},
you can ignore the parameter like receiveChanA() does.

The job of cnator.Serve() is to spawn a go routine for each subscription made by cnator.Subscribe(..).

It provides some runtime validation like

  • whether the subscriber function doesn't satisfy the channel data type or
  • whether the channel has not been initialized (i.e. forget to make(chan ..)) etc

Full code & examples can be found at this repository : Cnator

Also posted on : https://blog.altiano.dev/cnator-channel-based-subscription-in-go

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