When people hear about real-time computing they often make the mistake of thinking that these have to be fast systems and are nearly always used for control of mechanical systems. It is true that in most cases the response times required are fast, but speed is not what defines a real-time system. The true core of a real-time environment is that the system will guarantee to perform some task within a pre-defined time so that the system's behaviour becomes fully deterministic.
For enterprise class applications what are the advantages (and possibly disadvantages) of deployment on a real-time system? In many cases there is no great advantage. Once the non-functional requirements of a system (load capacity, average response time, peak-load response time, and so on) have been met the application can be deployed and the customer is satisfied. Should something happen that makes a request to, say, an HR application take rather longer than usual the user simply has to wait longer; there is no measurable impact. However, for many financial, enterprise class applications failing to do something within a given time can easily be equated to a cost, possibly a very large one. Financial markets, by their very definition, are extremely volatile and computer trading systems mean that prices can change at the rate of many times a second. If one part of a system decides to make a trade based on the current price and the actual trade gets delayed for whatever reason even a small change can result in a significant loss of money. If this delay happens frequently the system soon becomes less of an advantage and more of a liability.
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