Additional components may be added to the trading system. We will talk about the following components (it is not an exhaustive list):
- Position server: This keeps track of all the trades. It updates the positions for all the traded financial assets. For instance, if a trade is made for 100,000 EUR/USD at a price of $1.2, the notional position will be $120,000. If a trading system component needs the position amount for EUR/USD, it will subscribe the position server for getting position updates. The order manager or the trading strategy may want to know this information before allowing an order to go out. If we want to limit the position to $200,000 for a given asset, another order to get 100,000 EUR/USD will be rejected.
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