SQL Service Broker provides support for messaging and queuing applications in the SQL server database engine. SQL Service Broker is an extension mechanism that allows you to queue events for asynchronous processing. Service Broker is an asynchronous messaging system. It allows you to send a message to a queue. It works in both simple and distributed DBs. A simple use case would be a logging queue. We used it at a client to queue xml messages to be processed asynchronously. So we push an XML to an InitatorQueue, and then had a service pull them from the queue, extract some necessary attributes via XPath, and insert them into a persistence table in our database.
It makes very simple for the developers to create complex applications that use a default database engine component to make an in-between communication for disparate databases.
Service Broker guarantees messages are received in the order they are sent in.
There is no intrinsic harm in enabling the broker if it’s not used it will just be idle.