Distributed Software Systems are subject to frequent changes. Middleware plays an important role in the development of evolvable systems. RMI, CORBA, DCOM and EJB are mechanisms to create, deploy and deal with object-oriented components in a distributed environment. Java’s contribution in distributed computing is to provide platform-independent, low-level code that can be dynamically loaded and linked. CORBA provides platform and programming language independence in a heterogeneous distributed environment. EJB and DCOM are distributed component models put forth by Sun Microsystems and Microsoft respectively. This book brings together the major object models used in distributed computing - RMI, CORBA, DCOM and EJB. This book is beneficial for all IT professionals and students. This book aims at explaining the features of DCOM, CORBA, RMI, CCM, EJB, and JavaBeans.