FISHNET: A Distributed Control Local Area Network

Preface Distributed real-time object-oriented software is a topic of much current interest; for example , the June, 2000 issue of the IEEE Computer magazine is a special issue on the subject. This document describes phases 1 and 2 of the High-Performance Distributed Multimedia (HPDM) task that is being carried out in the CREATE Lab. at UCSB in partnership with teams at the CalTrans TCFI and UCSD CVRRL. This is Research Thrust 5 of the DiMI ATON Project. Our goal is to provide a flexible and scalable distributed computing environment for the other ATON software development tasks, which involve multiuser virtual reality, distributed robots, complex real-time signal processing, large-scale simulation, distributed real-time databases, and wide-area (and wireless) networking. The introduction discusses general requirements for writing and deploying large-scale distributed software systems, such as is needed by the ATON DRIVE (Distributed Real-time Interactive Virtual Environment) and robotics efforts. After presenting the basic technology of the CORBA (Common Object Request Broker Architecture) system, we develop a proposal for an extension to the CORBA interface definition language (IDL) that adds Quality-of-Service (QoS) attributes to CORBA interfaces and provides information that can be used by an advanced CORBA run-time, naming and trading services. Taking these extensions, we investigate the CORBA audio/video (A/V) streaming standard with respect to our requirements and our infrastructure. The appendices present an in-depth example of CREATE's ExIDL (Extended IDL) language, as well as CORBA-related examples and property lists. Introduction A great deal of effort has been invested over the last decade in scalable distributed computing on multiprocessor systems. Recently, the CORBA (Common Object Request Broker Architecture) standard has gained wide acceptance as a framework for interprocess communication and coordination over (potentially) wide-area heterogeneous networks. Several software suppliers now have CORBA-compliant software packages (Object Request Brokers or ORBs) that allow programs written in a variety of object-oriented languages (e.g., C++, Java, or Small-talk) running on a wide range of hardware platforms to interoperate. There is also a competing single-vendor system called DCOM from Microsoft. Given these developments, it is now possible to perform wide-area distributed processing with little of the programming overhead associated with traditional multi-tier applications. This advance in technology has lead to a number of new application architectures, and to the widespread use of CORBA in many application domains, even areas where real-time interaction and controlled latency are required.