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The Real Time TCP Client acts as a PICS Real Time Database agent for the machine on which it runs. It handles all real time subscription requests from PICS applications by maintaining a list of points that it is currently receiving from the Real Time TCP Server. When a new point is requested, it is added to the TCP subscription. When the last subscription to a point is cancelled, the point is removed from the TCP subscription. The only exception to this is the PICS Time point. The time point is always requested by the TCP client in order to provide a "life clock" feature on the local node. If the time point ever stops arriving, the TCP client informs the local user that the real time data flow has been lost (assuming the watchdog feature is enabled).
By using TCP as our transport, this real time agent allows PICS clients to run anywhere on the internet that has access to a PICS Real Time TCP Server. By limiting the data to only the points absolutely necessary on the client machine, we keep the bandwidth requirements low. The RTClient also supports a feature limiting the delivery rate to further reduce bandwidth requirements for machines that do not require extremely fast data rates. The data rate limit is specified to an accuracy of 0.1 seconds (the lower limit for the data rate).
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