Hi @Hugoman, welcome to the Community!
If ActiveMQ broker app’s API supports webhook events for new messages, then it should be possible to subscribe to that event using Webhooks trigger in a Zap. Webhooks are a more advanced feature and API’s can vary greatly so we can’t give the exact setup you’d need for the trigger, but we do have some more general instructions provided in our Trigger Zaps from webhooks guide which may help.
If you run into any errors please share a screenshot of them here and the Community will do their best to help troubleshoot it with you. Remember to remove/hide any private information (like names, emails, addresses, API Keys etc.) from any screenshots before sharing.