The Guitarix engine can act as TCP server using the JSON-RPC 2.0 format, and the Guitarix user interface can connect as a client. The engine can be started in a "headless" mode, or include the user interface (called "local UI" in the diagrams).

The client works synchronously, i.e. it waits for the servers answer to an JSON-RPC call (blocking the glib main loop):

Server state changes are broadcasted to all clients except the one that triggered the state change (this client generally already knows the new state). Clients notified of a state change must not reflect that change back to the server (otherwise network delays and the delayed processing of asynchronous responses in the glib main loop can lead to strange effects or endless loops):

The Guitarix UI is constructed on the assumption that requested state changes happen synchronously. If the client needs to get information about the state change after triggering it, a call should be used instead of a notify, and the answer should include that information (the answer to the calling client might be sent before notifying other clients, the order is unspecified):

State changes can also be triggered by the local UI (or from inside the server engine):

Asynchronous notifications from the server are stashed away for the main glib event loop while waiting for a call answer: