README.md

Reactive Observables for Apache Kafka

This is a simple package for using Kafka in Golang with the Observer-pattern.

Example

We have two Kafka-topics in JSON and want to serialize the events in a pipeline.

Create new type

in order to serialize our events

type BookRequest struct {
	Book   string `json:"book"`
	Person string `json:"person"`
}

Create a new config

const config = &kafkaesque.Config{
		AutoOffsetReset:  kafkaesque.AutoOffsetReset.Latest,
		BootstrapServers: []string{"localhost:9092"},
		IsolationLevel:   kafkaesque.IsolationLevel.ReadCommitted,
		MessageMaxBytes:  1048588,
		ClientID:         "test_1",
		GroupID:          "test_group",
		SecurityProtocol: kafkaesque.SecurityProtocol.Plaintext,
    }

Create the consumer

testConsumer, err := kafkaesque.NewConsumer(config, "book-requests", "external-book-requests")
if err != nil {
	    panic(err)
    }

Serialize BookRequest

bookRequests := testConsumer.Events.
		Map(func(_ context.Context, item interface{}) (interface{}, error) {
			var request BookRequest
			err := json.Unmarshal(kafkaesque.ValueToBytes(item), &request)
			return request, err
		})

Show Types

for event := range bookRequests.Observe() {
		log.Println(fmt.Sprintf("%T", event.V))
	}

Test

Test Program

1. Start your Confluent Plattform:

   cd example
   docker-compose up

2. Start the program:

   go run . -name test_consumer -topics test

3. In a new terminal run:

   docker exec -it broker bin/kafka-console-producer --topic test --bootstrap-server localhost:9092

4. Insert a BookRequest in JSON:

   {"book": "Moby Dick", "person": "Max Musterknabe"}

   The output should be:

   2020/10/03 15:32:08 Showing events for [test test1 test2] on [localhost:9092]:
   2020/10/03 15:32:16 Book:	Moby Dick	Person:	Max Musterknabe
   

   Or start the example as producer:

   go run . -mode producer -name test_producer -topics test

   The output should be:

   2020/10/03 15:32:08 Showing events for [test test1 test2] on [localhost:9092]:
   2020/10/03 15:32:16 Book:	10 Awesome Ways to Photograph Blue Bottles	Person:	Pamela Osborne
   2020/10/03 15:33:02 Book:	10 Awesome Ways to Photograph Blue Bottles	Person:	Pamela Osborne
   2020/10/03 15:33:02 Book:	21 Myths About Blue bottles Debunked	Person:	Inayah Brown
   2020/10/03 15:33:02 Book:	How to Make Your Own Vast Hat for less than £5	Person:	Ikrah Blair
   2020/10/03 15:33:03 Book:	An analysis of handsome jugs	Person:	Aurora Stafford
                                   ...