目录 Abstract
1. What is Embedded Software?
2. Just Software on Small Computers?
3. Limitations of Prevailing Software Engineering Methods
4. Actor-Oriented Design
5. Examples of Models of Computation
6. Choosing a Model of Computation
7. Heterogeneous Models
8. Component Interfaces
9. Frameworks Supporting Models of Computation
10. Conclusions
11. Acknowledgements
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ACM, 33(9), pp. 125-141, 1990.
[3] G. A. Agha, Actors: A Model of Concurrent Computation in Distributed Systems,
MIT Press, Cambridge, MA, 1986.
[4] G. A. Agha, “Abstracting Interaction Patterns: A Programming Paradigm for Open
Distributed Systems,” in Formal Methods for Open Object-based Distributed
Systems, IFIP Transactions, E. Najm and J.-B. Stefani, Eds., Chapman

Abstract The science of computation has systematically abstracted away the physical world. Embedded software systems, however, engage the physical world. Time, concurrency, liveness, robustness, continuums, reactivity, and resource management must be remarried to computation. Prevailing abstractions of computational systems leave out these “non-functional” aspects. This chapter explains why embedded software is not just software on small computers, and why it therefore needs fundamentally new views of computation. It suggests component architectures based on a principle called “actor-oriented design,” where actors interact according to a model of computation, and describes some models of computation that are suitable for embedded software. It then suggests that actors can define interfaces that declare dynamic aspects that are essential to embedded software, such as temporal properties. These interfaces can be structured in a “system-level type system” that supports the sort of design-time and run-time type checking that conventional software benefits from. 1. What is Embedded Software? Deep in the intellectual roots of computation is the notion that software is the realization of mathematical functions as procedures. These functions map a body of input data into a body of output data. The mechanism that is used to carry out the procedure is not nearly as important as the abstract properties of the function. In fact, we can reduce the mechanism to seven operations on a machine (the famous Turing machine) with an infinite tape capable of storing zeros and ones [83]. This mechanism is, in theory, as good as any other mechanism. And therefore, the significance of the software is not affected by the mechanism.