TCP processing for devices

A data processing system comprising:

• a host processing device supporting a host transport engine operable to establish one or more transport streams over a network with a remote peer, the host transport engine maintaining state for each transport stream, wherein the host transport engine is configured to:
• after establishing a first transport stream, pass state information for the first transport stream to a device transport engine of network device hardware separate from the host processing device to permit the device transport engine to perform transport processing of the first transport stream;
• and
• the network device hardware separate from the host processing device, the network device hardware comprising:
• memory configured to store packet template values, and
• at least one circuit configured to perform:
• processing, by the device transport engine on the at least one circuit of the network device hardware, the first transport stream to extract payload data from received packets;
• receiving, at a device application on the at least one circuit of the network device hardware that is separate from the host processing device, the extracted payload data;
• determining, by the device application on the at least one circuit of the network device hardware, responsive payload values based on the extracted payload data;
• providing, by the device application on the at least one circuit of the network device hardware, said responsive payload values to the device transport engine on the at least one circuit of the network device hardware;
• and
• forming, by the device transport engine on the at least one circuit of the network device hardware, transport data packets for output onto the network, wherein each of at least some of said transport data packets comprises at least some of the template values and at least some of the responsive payload values in a payload of the respective transport data packet.