A message broker receives a published message from a publisher program. Responsive to identification of one or more subscriber programs subscribing to messages of the type of the received message, the broker forwards the received message to the one or more subscriber programs. Matcher components compares the received message with stored subscriptions to identify subscriber programs, generates an alert when an alert condition is satisfied, and compares the generated alert with stored subscriptions to identify subscriber programs subscribing to the alert. The alert is then forwarded to the subscriber program subscribing to the alert.