This example shows a typical flow for the persistence of data across agent restarts.

datapersist.agent.nut

// Load the data from persistent storage
settings <- server.load();
 
// It the load is null, it tells us this is the first time the agent is running
if (settings.len() == 0) {
    // Set and save defaults
    settings = { "colour" : { "r" : 255, 
                              "g" : 0, 
                              "b" : 0 },
                 "state"  : 0 };
    
    local result = server.save(settings);
    if (result != 0) server.error("Could not save settings");
}
 
// Establish HTTP request handler to persist settings changes
http.onrequest(function(request, response) {
    try {
        // If there's a state query parameter
        if ("state" in request.query) {
            // Update settings table and save it
            settings.state = req.query.state;
            local result = server.save(settings);
            if (result != 0) server.error("Could not save settings");
        }
        
        response.send(200, "OK");
    }
    catch (err) {
        server.error("Server error: " + err);
    }
});