Serialization surprises

CONTEXT I want to share a problem that we had in our project. We were doing a real-time "Profits and Loss" server (P&L). The server sends stock updates to all the users subscribed to the stocks, basically as Google Finance or Yahoo Finance. SIMPLE IMPLEMENTATION I will used a basic approach (no aggregation and no optimization) to explain the problem that we had with Serialization and Hessian. The server always keep the last value on the stocks, because when a user ask for a quote we want to send back as soon as possible the last value (from the cache) that we had on that stock). We kept the stock prices (BID and ASK) in a simple object : SymbolSerializable. When a update is received for a stock, we update the values in his SymbolSerializable and send back the updated values to all client subscribed to this stock. ... symbol.setBid(update.getBid()); symbol.setAsk(update.getAsk()); ... for(Client client : clientList){ client.sendUpdate(symbol); } .... It can't be more simpler than that. The client will received each updates on his stocks. The problems that we had was surprising. The clients were receiving the always the same price on a stock ! WHY ? here an example : stock : ABC Updates : 1 : bid=10.25$, ask=10.50$ 2 : bid=11.50$, ask=11.75$ 3 : bid=12.00$, ask=12.15$ and the clients received : 1 : bid=10.25$, ask=10.50$ 2 : bid=10.25$, ask=10.50$ 3 : bid=10.25$, ask=10.50$ To debug ...

Date: August, 06 2010
Url: http://www.java.net/blog/survivant/archive/2010/08/06/serialization-surprises

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