Distributed Interactive Simulation (DIS) is the standard network protocol that promises to provide a common ground for the interplay of a variety of simulators in a single, integrated exercise. Many new training systems procurements require DIS support and, of course, mandate that such support be written in Ada. This in itself can be daunting, because Ada's rigid structure does not easily accommodate the complexity and diversity of information that constitutes the protocol. However, if the concept is to succeed it must also take into account the vast array of simulators that already exist, which will require implementation of DIS in all of the programming languages that preceded Ada.

This paper will examine the DIS protocols from the perspective of software implementation, and will discuss the problems and pitfalls of supporting those protocols in the variety of languages used in today's simulators. The features and quirks of these languages - strong typing, variable-length record support, dynamic allocation, and so on - will be explored for their effect on implementing the protocols. Specifically, Grumman's experience with implementing DIS in Ada, C, Pascal, and FORTRAN will be discussed. Each language has its own peculiar way of defining and manipulating data structures, and each has its good and bad points when applied to DIS.