Abstract: A multi-threaded, multi process distributed system including remote call procedure (RPC) messages. The threads in the distributed system are each associated with a queue. The RPC messages each include an identifier to identify the queue which is associated with the thread which has originated the RPC message, as well as an identifier indicating the connection over which the RPC message is communicated from one process to another. The connection over which RPC requests are forwarded in the distributed system is made between one process and another process. The RPC messages sent between processes utilise the same connection, independent of which thread in each process is sending or receiving the messages. RPC messages are forwarded through the distributed system and the connection and queue identifiers in the RPC messages are updated as the message is forwarded from process to process in the distributed system.