Modular Multiprogramming

多道程序设计研究的两个主要目标是：(1)在不考虑其他模块干扰的情况下，独立地设计和理解程序的模块（例如，进程或数据对象），以及(2)在具有细粒度交错的独立处理器上实现模块，以便处理器不会长时间被锁定而无法访问公共数据。此外，必须设计一种模型，消除计算和通信之间的区别；特别是，接口的设计和推理方法应该与网络节点上的计算方法没有什么不同。该项目基于这样一个假设：许多为数据库、面向对象编程和响应式系统设计开发的编程概念可以统一到一个紧凑的分布式程序模型中，以满足预期的目标。在过去，通过采用各种同步机制（锁或信号量、关键区域、监视器和通信）来限制模块之间的干扰已经付出了很多努力。在这个项目中，除了过程调用之外，没有将特定的通信或同步机制内置到模型中。然而，使用有界或无界通道、信号量和访问共享内存的传统通信方案可以编码为模块。这个项目使用两种不同的过程，对编程的顺序和并发方面进行建模。编程模型允许这两种类型的过程之间有规则的交互。该研究旨在：(1)开发模型，特别是动态创建模块的模型；(2)在现有语言之上实现模型；(3)开发适当的形式化来指定和验证程序的属性。

Two major goals in multiprogramming research are: (1) to design and understand the modules (e.g., processes or data objects) of a program in isolation, without considerations of interference by the other modules, and (2) to implement the modules on separate processors with a fine grain of interleaving so that no processor is ever locked out of accessing common data for long periods of time. Further, it is essential to devise a model in which the distinction between computation and communication is removed; in particular, the methods for designing and reasoning about the interfaces should be no different from those employed for the computations at the nodes of the network. The project is based on the hypothesis that many of the programming concepts developed for databases, object-oriented programming and designs of reactive systems can be unified into a compact model of distributed programs that meets the desired goals. In the past, much effort has gone into limiting interference among the modules by employing a variety of synchronization mechanisms: locks or semaphores, critical regions, monitors and communication. In this project, no specific communication or synchronization mechanism, except procedure call, is built into the model. Yet, the traditional schemes for communication using bounded or unbounded channels, semaphores, and accesses to shared memory can be encoded as modules. This project uses two distinct kinds of procedures, to model sequential and concurrent aspects of programming. The programming model allows for disciplined interactions between these two types of procedures. The research seeks to: (1) develop the model, in particular for dynamic creations of modules (2) implement the model on top of an existing language, and (3) develop the appropriate formalism to specify and verify the properties of programs.