RealTimeTalk is a framework and an object-oriented language for distributed hard real-time systems. This paper presents past, present, and future work in the RealTimeTalk project. It concentrates on the language and programming part of RealTimeTalk, and the problems a dynamically typed language impose on a real-time system.We look at how some of these problems can be solved by type inference and how type information can assist the compiler in accepting larger classes of real-time programs, generate more efficient and deterministic code, provide better estimation of execution times, and avoid run-time type errors. With type inference, one can have the best of two worlds -efficiency and type safety, without the need for manual type declarations. An example is used to illustrate these ideas.

RealTimeTalk (RTT) is a design framework for developing distributed real-time applications with both hard and soft requirements. The framework supports design via hierarchical decomposition.We believe that object-orientation is the best way to go about structuring a problem, hence the RTT language is based on Smalltalk with an analysis frontend to infer type information for run-time safety, and to yield more precise estimations of execution times.Unlike most real-time systems, RTT does not force the designer to embed constructs for timing requirements, communication, and synchronization in the code. Rather, such information is specified on a higher level of abstraction using graphical tools. This not only keeps the code "clean" but also simplifies timing analysis and resource allocation.A comparison with other real-time systems concludes the paper.