Generalized Image Library: A Durra Application Example

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 writing task descriptions and type declarations for a subset of the Generalized Image Library, a collection of utilities developed at the Department of Computer Science at Carnegie Mellon University. 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 GIL 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. A few sample application descriptions were developed as part of the experiment and are also reported in this document.