With the Adaptive Communication Environment (ACE), developers have what they've long sought: a mature, open source, object-oriented framework for building enterprise applications more rapidly and cost-effectively. Now, ACE's creator and one of its leading consultants present the first comprehensive guide to ACE -- and to building extensible object-oriented software with C++ in distributed, heterogeneous environments. The authors begin by describing the key design challenges that arise when objects are distributed beyond a single thread in a single process. They demonstrate how middleware and the ACE toolkit can be applied together to address many of these challenges; and introduce a taxonomy of middleware layers for understanding and solving distributed design problems. It then shows how ACE provides flexible, portable, and efficient support for each of these design dimensions. Extensive C++ code samples are provided. For all developers, analysts, and architects using C++ to build enterprise applications.