ACE is one of many solutions to a common problem: making easy to use powerful but complex features of modern operating systems like inter-process communication, thread management, efficient memory management and so on. It was developed at the University of California, Irvine.
ACE is written in C++ and runs on a wide variety of operating systems (must Unixes, Microsoft Windows various versions, real-time systems like VxWorks and QnX). It enjoyed some success in the communication industry, notably for Motorola Iridium satellites.