The GRAVA self-adaptive architecture: history; design; applications; and challenges

In 1998 DARPA embarked on a program to develop self-adaptive software. One architecture that emerged from that effort was the GRAVA architecture. The GRAVA architecture has by now been applied to a number of challenging domains and continues to be extended and applied to ever more challenging problems. An overview is provided of the history that motivated the program, the design of the GRAVA architecture, and the applications to which it is being applied. Challenges and open problems are discussed.