<lightning:container aura:id="ReactApp"
                             src="{!$Resource.SendReceiveMessages + '/index.html'}"
                             onmessage="{!c.handleMessage}"
                             onerror="{!c.handleError}"/>

({
    sendMessage : function(component, event, helper) {

        var msg = {
            name: "General",
            value: component.get("v.messageToSend")
        };
        component.find("ReactApp").message(msg);
    },

    handleMessage: function(component, message, helper) {
        var payload = message.getParams().payload;
        var name = payload.name;
        if (name === "General") {
            var value = payload.value;
            component.set("v.messageReceived", value);
        }
        else if (name === "Foo") {
            // A different response
        }
    },

    handleError: function(component, error, helper) {
        var e = error;
    }
})