Message-passing database machines

The development of message-passing database machines is briefly examined, with emphasis on the Active Graph Model (AGM). The AGM, developed specifically to exploit massive parallelism, is based on the principles of purely message-driven computation, where the entire database is represented as a graph of communicating nodes. Unlike object-oriented models, however, where the programmer must provide the methods for message handling, in AGM, generic methods are an inherent part of the model. This results in a much finer grain of parallelism than is obtained with object-oriented systems. Since both memory and control are encapsulated within each node, the database is capable of exploiting an architecture consisting of a very large number of loosely coupled processors and disk units. A hardware prototype consisting of 16 processors and 16 disks is now operational.<>