In many pub/sub systems, publishers post messages to an intermediary message broker or event bus, and subscribers register subscriptions with that broker, letting the broker perform the filtering.
En moitos sistemas pub/sub, os editores publican mensaxes a un intermediario o intermediario de mensaxes ou o bus de eventos, e os subscritores rexistran as subscricións a ese intermediario, o que permite que o intermediario realice o filtrado.