A data mediation method involves receiving an incoming data stream from a data communication network; analyzing the incoming data stream to determine an inbound second-format message for transport in the network; processing a part of the inbound second-format message by parsing a selected subset of the message parameters; generating a run-time data structure to represent the parsed message parameters in the selected subset; processing the generated run-time data structure by applying a data mediation logic which defines actions to be taken upon incoming data messages, the actions including adaptation of the generated data structure by modifying any of the message parameters in the selected subset and/or adding new message parameters based on the parsed message parameters; building an outbound second-format message from the inbound second-format message and the generated data structure; and sending the outbound second-format message in an outgoing data stream on the network.