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In this paper, we discuss a real-time communication model for
distributed systems, called the time polymorphic invocation
(TPI), introduced to our distributed real-time object model DRO
model. We first characterize distributed systems by following two
properties that have to be supported: least suffering and
best effort. The DRO model and its communication model TPI complies
these properties. We can classify the definition of TPI's behavior into
two types: receiver-defined TPI and sender-defined TPI.
We discuss advantages and disadvantages of both types of TPIs, and
implement a prototype system of the DRO model on the ARTS kernel, and
evaluate the efficiency of the current implementation as well as
confirm the high expressive power of the model.