KafkaExternalService

An ExternalService wrapping a Kafka cluster, exposing its topics as collections in the Skip runtime.

This adapter allows to easily create Kafka consumers, subscribing to external event/message streams and exposing their content as eager collections within the Skip runtime.

For a usage example, refer here.

Remarks

Subscription params may specify a fromBeginning boolean, which controls whether to consume all Kafka messages from the cluster, or only those sent since the creation of this external resource.

Implements

• ExternalService

Constructors

new KafkaExternalService()

new KafkaExternalService(
   kafka_config, 
   messageProcessor, 
   consumerOptions): KafkaExternalService

Parameters

Parameter	Type
kafka_config	{ brokers: object[]; clientId: string; logLevel: logLevel; }
kafka_config.brokers	object[]
kafka_config.clientId	string
kafka_config.logLevel?	logLevel
messageProcessor	(msg) => Iterable<[Json, Json]>
consumerOptions	Omit<ConsumerConfig, "groupId">

Returns

KafkaExternalService

Methods

shutdown()

shutdown(): Promise<void>

Shutdown the external service.

Returns

Promise<void>

Implementation of

ExternalService.shutdown

---

subscribe()

subscribe(
   instance, 
   topic, 
   params, 
   callbacks): Promise<void>

Subscribe to a resource provided by the external service.

Parameters

Parameter	Type	Description
instance	string	Instance identifier of the external resource.
topic	string	Name of the Kafka topic to expose as a resource.
params	{ fromBeginning: boolean; }	Parameters of the external resource.
params.fromBeginning?	boolean	Controls whether to consume all Kafka messages from the cluster, or only from the creation of this external resource.
callbacks	{ error: (error) => void; update: (updates, isInit) => Promise<void>; }	Callbacks to react on error/update.
callbacks.error	(error) => void	Error callback.
callbacks.update	(updates, isInit) => Promise<void>	Update callback.

Returns

Promise<void>

Implementation of

ExternalService.subscribe

---

unsubscribe()

unsubscribe(instance): void

Unsubscribe from a resource provided by the external service.

Parameters

Parameter	Type	Description
instance	string	Instance identifier of the external resource.

Returns

void

Implementation of

ExternalService.unsubscribe