Practical Microservices

Sending the Email

With the infrastructure bits in place, we can move onto actually sending the email. Let’s write the handler for the Send command:

video-tutorials/src/components/send-email/index.js

function createHandlers ({
  justSendIt,
  messageStore,
  systemSenderEmailAddress
}) {
  return {
    Send: command => {
      const context = {
        messageStore,
        justSendIt,
        systemSenderEmailAddress,
        sendCommand: command
      }

      return Bluebird.resolve(context)
        .then(loadEmail)
        .then(ensureEmailHasNotBeenSent)
        .then(sendEmail)
        .then(writeSentEvent)
        // If it's already sent, then we do a no-op
        .catch(AlreadySentError, () => {})
        .catch(
          SendError,
          err => writeFailedEvent(context, err)
        )
    }
  }
}

It uses a Promise ...