OCPP: keep websocket alive between heartbeats

charger/ocpp/const.go

@@ -4,6 +4,14 @@ import "time"
 
 var Timeout = time.Minute // default request / response timeout on protocol level
 
+const (
+	heartbeatInterval = time.Minute // heartbeat interval requested in BootNotification
+
+	// pingWait must exceed heartbeatInterval, otherwise chargers not sending
+	// websocket pings are disconnected while idle
+	pingWait = 3 * heartbeatInterval
+)
+
 // TriggerBootDelay defines how long to wait after WebSocket connect before
 // proactively triggering a BootNotification. This allows the connection to
 // stabilize and gives the charger a chance to send a spontaneous BootNotification.

charger/ocpp/cp_core.go

@@ -16,7 +16,7 @@ var (
 func (cp *CP) OnBootNotification(request *core.BootNotificationRequest) (*core.BootNotificationConfirmation, error) {
 	res := &core.BootNotificationConfirmation{
 		CurrentTime: types.Now(),
-		Interval:    60,
+		Interval:    int(heartbeatInterval.Seconds()),
 		Status:      core.RegistrationStatusAccepted,
 	}
 

charger/ocpp/cp_core_test.go

@@ -28,6 +28,9 @@ func TestBootNotificationStoresResultAndConnects(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, core.RegistrationStatusAccepted, res.Status)
 
+	// heartbeat must stay below the websocket inactivity timeout
+	assert.Less(t, time.Duration(res.Interval)*time.Second, pingWait)
+
 	// should be connected after BootNotification
 	assert.True(t, cp.Connected(), "should be connected after BootNotification")
 	assert.Equal(t, bootReq, cp.BootNotificationResult, "should store boot result")

charger/ocpp/instance.go

@@ -140,6 +140,10 @@ func NewServer(cfg Config, networkExternalUrl string) {
 	server := &interceptingServer{Server: ws.NewServer()}
 	server.SetCheckOriginHandler(func(r *http.Request) bool { return true })
 
+	timeouts := ws.NewServerTimeoutConfig()
+	timeouts.PingWait = pingWait
+	server.SetTimeoutConfig(timeouts)
+
 	dispatcher := ocppj.NewDefaultServerDispatcher(ocppj.NewFIFOQueueMap(0))
 
 	endpoint := ocppj.NewServer(server, dispatcher, nil, core.Profile, remotetrigger.Profile, smartcharging.Profile, security.Profile, firmware.Profile)