KafkaMessageBus

A general purpose message bus.

Releasing

To release a new version of kafka_message_bus in hex be sure to update the 'version' number under 'project' in mix.exs.

Installation

The package can be installed by adding kafka_message_bus to your list of dependencies in mix.exs:

def deps do
  [{:kafka_message_bus, "~> 3.0"}]
end

And, for now, this configuration is required:

config :exq,
  start_on_application: false

Usage

The following configuration is expected:

config :kafka_message_bus,
  source: "source",
  default_topic: "default_topic",
  adapters: [
    AdapterModule
  ]

Where:

The adapters themselves also require some configuration.

config :kafka_message_bus, KafkaMessageBus.Adapters.Kaffe,
  consumers: [
    {"kafka_topic", "kafka_resource", YourApp.ResourceConsumer}
  ],
  producers: ["another_topic"],
  endpoints: ["first-broker": 9092, "second-broker": 9092],
  namespace: "kafka_consumer_group"

The kafka_message_bus supports injecting message data validators to enforce message contracts on data passed through the bus. There is no message data validation by default and the related configuration settings are not required.

The following configuration is required for message validation support. The user must provide a message data factory implementation that presents n number of on_create/3 functions. Each on_create function will invoke message_data new/1 function for a message data struct that also implements the MessageData validate/1 function. This project includes a SampleMessageDataFactoryImplementation that illustrates how to write one of these factory implementation modules.

config :kafka_message_bus, :message_contracts,
  message_data_factory_implementation:
    KafkaMessageBus.Examples.SampleMessageDataFactoryImplementation

To control which message contracts are enforced use the following configuration settings:

config :kafka_message_bus, :message_contracts, exclusions: :none

Will enforce all message contracts.

config :kafka_message_bus, :message_contracts, exclusions: :all

Will exclude all message contract enforcement. Message processing will continue to work as it has in the past.

config :kafka_message_bus, :message_contracts, 
  exclusions: [MessageDataImplementation1, MessageDataImplementation2]

Will exclude message_contracts by name.