Emitters

Setting up an emitter requires

• a list of brokers
• a target topic
• a target codec

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emitter, err := goka.NewEmitter([]string{"localhost:9092"}, "topic-name", new(codecs.Int64))
// handle error

// wait for all outstanding messages to be sent
err := emitter.Finish()
// handle error

Emitters write key-value pairs into a specific kafka topic. Encoding the message is done by a codec.

The emitter determines the partition based on the key using a hasher passed to the underlying sarama partitioner partitioner.

Messages can be sent

• asynchronously (using the underlying producer’s batching) using Emit or

  Asynchronous calls return a EmitSync that can be used to subscribe on success or failure of the operation.

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prom, err := emitter.Emit("key", int64(123))
// handle error

prom.Then(func(err error){
  if err != nil{
    // handle asynchronous error
  }
})

• synchronously using EmitSync. The call returns when the message was sent or failed.

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err := emitter.EmitSync("key", int64(124))
// handle error