Provided are a message brokering systems, computer program products and methods for communication in a publish/subscribe environment in which publisher application programs send messages to subscriber application programs via one or more message brokers, the method comprising the following steps: responsive to receipt of a published message at a message broker, referring to characteristics of the received message and subscriber-specified quality of service requirements to determine an appropriate quality or service for onward transmission of the message; selecting a communication protocol in accordance with the determined quality of service; and transmitting the message using the selected communication protocol. Information relating to the quality of service requirements of a first message broker's subscribers is passed to other brokers and subsequently used for selection of an appropriate communication protocol for transmitting messages between the brokers.