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This document describes the use of Durra, a task-level application description language, and its associated toolset. The Durra environment supports the development of highly reconfigurable distributed ADA applications. The intended audience for this document is system managers responsible for Durra installation and Durra application developers.

Durra is a language designed to support the development of distributed programming applications consisting of concurrent, large-grained processes devoted to specific pieces of the application. During execution time the application processes run on possibly separate processors, and communicate with each other by sending messages of different types across communication links. The application developer is responsible for prescribing a way to manage all of these resources, called a task-level application description. It describes the processes to be executed, the assignments of processes to processors, and the communication channels required to transmit messages data between processes. Durra is a task-level description language, a notation in which to write these application descriptions. This document is a revised version of the original reference manual. It describes the syntax and semantics of the language and incorporates all the language changes introduced as a result of our experiences writing application descriptions in Durra. A companion document, Durra: A Task-Level Description Language User's Manual, describes how to use the compiler and support tools.

Durra is a language designed to support the construction of distributed applications using concurrent, coarse-grain tasks running on networks of heterogeneous processors. An application written in Durra describes the tasks to be instantiated and executed as concurrent processes, the types of data to be exchanged by the processes, and the intermediate queues required to store the data as they move from producer to consumer processes. This report describes an experiment in implementing a command, control, communications and intelligence (C3I) node using reusable components. The experiment involves writing task descriptions and type declarations for a subset of the TRW testbed, a collection of C3I software modules developed by TRW Defense Systems Group. The experiment illustrates the development of a typical Durra application. This is a three-step process: first, a collection of tasks (programs) is designed and implemented (these are the testbed programs); second, a collection of task descriptions corresponding to the task implementations is written in Durra, compiled, and stored in a library; and finally, an application description is written in Durra and compiled, resulting in a set of resource allocation and scheduling commands to be interpreted at runtime.