Redistribution in distributed Ada

In this paper we will demonstrate how Ada and its Distributed Annex may be used to relocate concurrent objects in a distributed data ow application. This relocation mechanism will provide the capability of providing both passive and active fault tolerance. Special care will be taken to demonstrate how errors are trapped and propagated across partitions containing multiple threads of execution. 1 The Model We rst summarize a model presented in a prior paper 4 . A data ow graph is de ned as a directed acyclic graph with data passing through the directed edges, or queues, and dynamics at the nodes. Each queue is connected to exactly two nodes: an upstream node attached to its tail and a downstream node attached to its head. Data ows downstream. Each node possesses a set of input queues entering it, and a set of output queues leaving it, either set possibly being empty. Each queue contains a threshold and a bu er size and receives its data in a rst-in- rst-out fashion from its upstream no...

• Type: Conference
• Year: 1999
• Where: SIGADA
• Authors: Scott James
• Keywords: Data Ows, Node, Programming Languages, SIGADA 1999, Upstream Node