Trading Example Part 1. Create a trade service

One of the things I love about dynamic data is no matter what the nature of the data which you are dealing with the code will look the same. I also love the power of data transformations and just how easy it is to tame sequences of data. However a lot of the capability and power is not obvious at a glance so this is the start of a series of posts where step by step I will illustrate usage of the library. I have decided to go in at the deep end and demonstrate a trading system as these systems generally have rapidly moving data and loads of complexity. What I hope to achieve is to show that by using dynamic data your code can be simplified greatly.

Source code can be found here

We will start off with a simple trade object

    public class Trade
    {
        public long Id { get; private set; }
        public string CurrencyPair { get; private set; }
        public string Customer { get; private set; }
        public decimal Price { get; set; }
        public TradeStatus Status { get; private set; }

        public Trade(long id, string customer, string currencyPair, TradeStatus status)
        {
            Id = id;
            Customer = customer;
            CurrencyPair = currencyPair;
            Status = status;
        }
    }

I want a service which exposes a load of trades.

    public interface ITradeService
    {
        IObservableCache<Trade, long> Trades { get; }
    }

Implementing this is a trivial matter. For clarity not all code is shown.

    public class TradeService : ITradeService
    {
        private readonly IObservableCache<Trade, long> _tradesCache;

        public TradeService()
        {
            //create a cache specifying that the unique key is id
            var tradesSource = new SourceCache<Trade, long>(trade => trade.Id);

            //call AsObservableCache() to hide the update methods as we are exposing the cache
            _tradesCache = tradesSource.AsObservableCache();

           //code to emulate an external trade provider
            var tradeLoader = GenerateTradesAndMaintainCache();

            //.....
        }

        public IObservableCache<Trade, long> Trades
        {
            get { return _tradesCache; }
        }
    }

We now have a trades service which I will be using in subsequent posts to demonstrate the functionality of dynamic data.

Part 2

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