A method of transmitting data for use at a data processing system and network interface device, the data processing system being coupled to a network by the network interface device, the method comprising: forming a message template in accordance with a predetermined set of network protocols, the message template including at least in part one or more protocol headers; forming an application layer message in one or more parts; updating the message template with the parts of the application layer message; processing the message template in accordance with the predetermined set of network protocols so as to complete the protocol headers; and causing the network interface device to transmit the completed message over the network.