No, your trading engine is on the other end, the link only sends prices. Let's assume you want to trade on a future in Chicago that's based on London prices (e.g. a world wide equity index). You know Chicago prices and NYC prices and what people in Chicago think London prices are. If you then get from London a price indication that this has changed, you can quickly trade against it to make money. The London link never needs to know what happened, they just send prices that could be interesting. All logic sits at the exchange where trades happen since that's dependent on local prices at time of execution.