BusConfiguration

Creates a configuration in order to initialize a new BusInstance.

Methods

withHandler(classHandler)

Registers a class handler that receives a message and performs a unit of work. When Bus is initialized it will configure the transport to subscribe to the type of message handled by the handler and upon receipt will forward the message through to the handle() function.

Arguments

Argument	Description	Default
classHandler	A class responsible for handling messages that implements Handler	None

Example

import { Bus } from '@node-ts/bus-core'
import { TestHandler } from './test-handler'

Bus.configure().withHandler(TestHandler)

See also events, commands.

withHandler(functionHandler)

Registers a function handler that receives a message and performs a unit of work. When Bus is initialized it will configure the transport to subscribe to the type of message handled by the function handler and upon receipt will forward the message to the function.

Arguments

Argument	Description	Default
functionHandler	A functional handler mapping initialized using handlerFor	None

Example

import { Bus, handlerFor } from '@node-ts/bus-core'
import { TestEvent } from './test-event'

Bus.configure().withHandler(handlerFor(TestEvent, event => {}))

See also events, commands.

withCustomHandler(messageHandler, customResolver)

Registers a custom handler that receives messages from external systems, or messages that don't implement the Message interface from @node-ts/bus-messages.

Arguments

Argument	Description	Default
messageHandler	A handler that receives the custom message	None
customResolver	A discriminator that determines if an incoming message should be mapped to this handler	None

Example

import { Bus } from '@node-ts/bus-core'
import { S3Event } from 'aws-sdk'

Bus.configure()
  .withCustomHandler(
    async (event: S3Event) => console.log('Received S3 event', { event }),
    {
      resolveWith: event => event.Records
        && event.Records.length
    }
  )   

See also System messages.

withWorkflow(workflow)

Registers a workflow definition so that all of the messages it depends on will be subscribed to and forwarded to the handlers inside the workflow.

Arguments

Argument	Description	Default
workflow	Workflow definition to register	None

Example

import { Bus } from '@node-ts/bus-core'
import { TestWorkflow } from './test-workflow'

Bus.configure().withWorkflow(TestWorkflow) 

See also Workflows.

withTransport(transport)

Configures Bus to use a different transport than the default MemoryQueue.

Arguments

Argument	Description	Default
transport	A configured transport to use	None

Example

import { Bus } from '@node-ts/bus-core'
import { SqsTransport, SqsTransportConfiguration } from '@node-ts/bus-sqs'

const sqsConfiguration: SqsTransportConfiguration = {
  // ...
}
const sqsTransport = new SqsTransport(sqsConfiguration)
Bus.configure().withTransport(sqsTransport) 

See also Transports.

withLogger(loggerFactory)

Configures Bus to use a different logging provider than the default consoler logger.

Arguments

Argument	Description	Default
loggerFactory	A factory that creates a new logger	None

Example

import { Bus } from '@node-ts/bus-core'
import { CustomLogger } from './custom-logger'

Bus.configure().withLogger((target: string) => new CustomLogger(target))

See also Loggers.

withSerializer(serializer)

Configures Bus to use a different serialization provider. The provider is responsible for transforming messages to/from a serialized representation, as well as ensuring all object properties are a strong type.

Arguments

Argument	Description	Default
serializer	Serializer to use	None

Example

import { Bus } from '@node-ts/bus-core'
import { ClassSerializer } from '@node-ts/bus-class-serializer'

Bus.configure().withSerializer(new ClassSerializer())

See also Serializer.

withPersistence(persistence)

Configures Bus to use a different persistence provider than the default InMemoryPersistence provider. This is used to persist workflow data and is unused if not using workflows.

Arguments

Argument	Description	Default
persistence	Persistence provider to use	None

Example

import { Bus } from '@node-ts/bus-core'
import { PostgresPersistence, PostgresConfiguration } from '@node-ts/bus-postgres'

const postgresConfiguration: PostgresConfiguration = {
  connection: {
    connectionString: 'postgres://postgres:password@localhost:5432/postgres'
  },
  schemaName: 'workflows'
}
const postgresPersistence = new PostgresPersistence(postgresConfiguration)
Bus.configure().withPersistence(postgresPersistence)

See also Persistence.

withConcurrency(concurrency)

Sets the message handling concurrency beyond the default value of 1, which will increase the number of messages handled in parallel.concurrency

Arguments

Argument	Description	Default
concurrency	The number of messages that can be handled in parallel	None

Example

import { Bus } from '@node-ts/bus-core'

Bus.configure().withConcurrency(5)

withContainer(containerAdapter)

withContainer({
      get <T>(type: ClassConstructor<T>) {
        return container.get<T>(type)
      }
    })

Use a local dependency injection/IoC container to resolve handlers and workflows.

Configures Bus to use a different persistence provider than the default InMemoryPersistence provider. This is used to persist workflow data and is unused if not using workflows.

Arguments

Argument	Description	Default
containerAdapter	An adapter that allows Bus to resolve class instances from the underlying IoC container	None

Example

import { Bus } from '@node-ts/bus-core'
import { Container } from 'inversify'

const container = new Container()
Bus.configure().withContainer({
      get <T>(type: ClassConstructor<T>) {
        return container.get<T>(type)
      }
})   

See also Dependency injection.

withMessageReadMiddleware(middleware)

  withMessageReadMiddleware<TransportMessageType = unknown> (
    messageReadMiddleware: Middleware<TransportMessage<TransportMessageType>>
  )

Run custom middleware before/after the point a message is read from the transport and then dispatched to handlers and workflow handlers.

Arguments

Argument	Description	Default
middleware	A middleware function that will be executed after a message is read from the transport and before it is dispatched to handlers.	None

Example

import { Bus, Middleware, Next, TransportMessage } from '@node-ts/bus-core'

const messageTimingMiddleware = async (
  context: TransportMessage<unknown>,
  next: Next
) => {
  const start = Date.now()
  await next()
  const end = Date.now()
  const durationMs = end - start
  console.log(
    'Message handled',
    { messageName: context.domainMessage.$name, durationMs }
  )
}
const bus = await Bus.configure()
  .withMessageReadMiddleware(messageTimingMiddleware)

See also Middleware.

withRetryStrategy(retryStrategy)

  withRetryStrategy({
    calculateRetryDelay (currentAttempt: number): number
  })

Configure the bus to use a different retry strategy instead of the default.

Arguments

Argument	Description	Default
retryStrategy	An implementation of RetryStrategy that calculates the delay between retrying failed messages.	DefaultRetryStrategy

Example

const bus = await Bus.configure()
  .withRetryStrategy({
    calculateRetryDelay (currentAttempt: number) { return Math.pow(2, currentAttempt) }
  }) 
  .initialize()

See also Retry Strategies.

initialize([options])

Initialize a configured BusInstance. This should be called after all options have been provided for the configuration.