private static Message marketDataRequest(String symbol, char subscriptionRequestType) {
MarketDataRequest tickerRequest = new MarketDataRequest();
NoRelatedSym noRelatedSym = new NoRelatedSym();
noRelatedSym.set(new Symbol(symbol));
tickerRequest.addGroup(noRelatedSym);
tickerRequest.set(new MDReqID("123")); // any value
tickerRequest.set(new SubscriptionRequestType(subscriptionRequestType));
tickerRequest.set(new MarketDepth(0));