@dvsa/business-events

Helper library for publishing business events.

Pre-requisites

• Node.js (Please see .nvmrc in the root of the repo for a specific version)
• npm (If using n or nvm, this will be automatically managed)
• Security
  • Git secrets
  • ScanRepo
    • Unzip repo-security-scanner_<version>_Darwin_<architecture>.tar.gz and rename the executable inside the folder to scanrepo - Add executable to path (using echo $PATH to find your path)

Getting started

Run the following command after cloning the project

1. npm install (or npm i)

Using this package

Extend the EventFactory class as demonstrated in the TestSystemEventFactory class. This pattern will allow the encapsulation of all business events for a particular domain e.g.

export class EnquirySystemEventFactory extends EventFactory {
  constructor(correlationId: string) {
    super(correlationId);
  }

  public feedJobInitiated = (feedType: string) =>
    super.create('ENQ_SYSTEM_DOMAIN_EVENTS', 'ENQ_UPDATE_NOP_INITIATED', feedType);
}

With a domain-specific event factory, generate a business event and call the BusinessEventPublisher.publish function.

const feedJobInitiatedEvent =
  EnquirySystemEventFactory.fromSqsRecord(sqsRecord).feedJobInitiated('evl');
BusinessEventPublisher.publish(feedJobInitiatedEvent);

Recommendations

Publishing business events should not impact the operation of a system. Failures should be logged and monitored, however the system should not respond to any errors in a way that impacts the expected behaviour of the system.