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Abstract. This tool paper gives an overview of Cadena -an integrated environment for building and modeling systems built using the CORBA Component Model (CCM). Cadena provides facilities for defining component types using CCM IDL, specifying dependency information and transition system semantics for these types, assembling systems from CCM components, visualizing various dependence relationships between components, specifying and verifying correctness properties of models of CCM systems derived from CCM IDL, component assembly information, and Cadena specifications, and producing CORBA stubs and skeletons implemented in Java. Cadena has been applied to build applications in Boeing's Bold Stroke framework for avionics mission-control systems. Cadena is implemented in IBM's Eclipse open-source IDE and is freely available.As software systems become more distributed, developers are increasingly turning to component-based development frameworks such Java Enterprise Beans (EJB) and the CORBA Component Model (CCM) to manage the complexities associated with building distributed systems. These frameworks aid application developers by providing services for common aspects such as distributed deployment, event notification, transactions, persistence, and security. Moreover, they use accepted design patterns (e.g., the event-oriented observer pattern) which enables a significant amount of code to be auto-generated. Component-based frameworks are also attractive because the relatively loose coupling between components facilitates reuse and allows systems to evolve gracefully as old components are switched out for new ones.Even in the domain of distributed real-time embedded (DRE) systems where hard/soft deadlines and minimal foot-print requirements traditionally have led

To support the trend toward component-based systems, the Cadena project aims to provide an Eclipse-based development environment that includes support for design, behavior modeling, formal reasoning, and automated code synthesis for systems built using the CORBA Component Model. In this paper, we describe the basic functionality of the Cadena tool, and summarize how it is currently being evaluated by industrial partners for use in developing highassurance avionics applications.

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The following reviews were selected from those recently published in to generate and recover exponentially modulated wave forms. The disvarious IEEE TRANSACTIONS and GrouplSociery Magazines and News-cussion of noise in FM goes deeper than usual in most underpaduate or letters. They are reprinted here to make them conveniently available to elementary graduate courses. The effects of noise in the high signal to the many readers who ozhenvise might not have ready access to them. noise ratio case are simply explained and sufficient references are in- Each review is followed by an identification of its original source.duded for more serious study. The chapter closes with a discussion of noise effects near threshold which is probably unnecessary and a bit too sketchy to be of much value to the elementary student. ChaDter seven is concerned with D U~ and & t a l modulation meth-Communication Systems Rinciples-Peyton Z. Peebles, Jr., (Reading, analyses are rather detailed and at times the author to lapse off ods kcluding PAM, PDM, PPM, k M , and d&a modulation. The MA: Addison-Wesley, 1976). Reviewed b y S. Riter, Texas A & M Uni-into very specialized topics of rather limited interest. The of versity, College Station, 77843.noise and its affect on these signals is difficult to follow because the Communication Systems Principles is an attempt by Professor Peyton Z. Peebles to develop a single text for the variety of courses now being offered to seniors and first year graduate students interested in communications. The book contains little that is new, few surprises, and nothing that this reviewer has not Seen in a similar form elsewhere. It is these characteristics which surprisingly make the book attractive. Because what Professor Peebles appears to have done is sift through the voluminous literature on communications, including both textbooks and joumals, extract the clearest, mast lucid explanations or communication systems phenomena, and present these explanations in an integrated fashion so that the book can be used as an effective teaching tool.The reader interested in the book as a teaching tool will perhaps, as this reviewer did, think that he' has seen all the material before. What strikes one, however, as he examines more carefully the derivations, explanations, and examples is that, while this material has in fact been seen before, it has been seen in a variety of bits and pieces. Professor Peebles has done a real seMce by pulling much of this information to-