Book excerpt: This document intends to offer a detailed discussion of selected distributed object-oriented architectures at conceptual level. The first part of the discussion offers a comprehensive overview of the Socket architecture in Java 2 and Berkeley UNIX and the distributed object model of Java Remote Method Invocation and the Common Object Request Broker Architecture. The second part concludes the discussion with a comparative study of selected features with emphasis on the Common Object Request Broker Architecture and Java Remote Method Invocation. Major Issues Include The TCP/IP Protocol Suite. We provide an introductory overview of the TCP/IP protocol suite and its architecture including layers and protocols. The TCP/IP architecture is based on three concepts: processes, layers and protocols. Sockets in Berkeley Unix. We present the Berkeley UNIX socket architecture in relation to the Internet communication domain and illustrate connection-oriented and a connectionless models of communication. Sockets in Java 2. We describe the Java 2 socket architecture, outline selected socket operations, introduce related packages and classes and conclude with a framework for a connection-oriented and connectionless model of communication. Remote Method Invocation in Java 2. We present a distributed object model in Java RMI, provide an overview of related interfaces, classes and packages and discuss security related issues. We conclude with the development of a framework for a distributed object application. Common Object Request Broker Architecture. We introduce a distributed object model for the Common Object Request Broker Architecture and outline design concepts including the Interface Definition Language and the Interoperable Naming Service. We conclude with the development of a framework for a distributed object application. Comparative Study of Distributed Architectures. We present a comparative study of socket architectures and distributed object models introduced in part o