Books

Useful tutorial on OSI applications Understanding OSI Applications by C. L Anson and A. Pell, Prentice- Hall, UK, 1992, s 370pp, ISBN 013-639-4442

This book provides a very thorough analysis of the upper layers of the OSI model with major emphasis on the application layers, thus comple- menting many of the textbooks which are directed at the lower layers. It provides a very pure analysis of these se'rv, ices and proto- cols, drawing the material directly from the various ISO and CCITT standards. The material presented is up-to-date, referring frequently t o the latest version of the ISO docu- ments, and this book goes a long way towards turning the mountain of ISO documents into a readable form.-

The emphasis is upon understand- ing the various primitives and con- structs which define the protocol at the appropriate layer rather than how these are or might be used in practice. Neither do the authors attempt to draw comparisons with de facto equivalent protocols, even if they are in wide usage. The empha- sis, being tutorial in nature, is pure OSI, and for those readers interested in-traditional OSI elements and protocols such as ACSE, CASE, SASE, CCR, TP, CMIS, CMIP, OSI Security, FTAM, X.400, X.500, MAP, JTM, VT, ASN.1, etc., this is excellent reading. How- ever, a good understanding of the OSI structure is a most desirable pre-requisite. One very useful fea- ture of the book lies in the introduc- t ion and d e f i n i t i o n o f new acronyms, for which OSI is never short. These are clearly defined at the start of the appropriate section within the chapter, and complement well the appendix on th~ major acronyms as well as the comprehen- sive index.

Structurally the book is very

sound. By the end of Chapter 2 the reader has completed the review of the OSI model and all layers up to and including the session layer.

Chapter 3 addresses ASM.1 and the Presentation layer. Chapter 4 and 5 focus on the Application layer topics such as its structure, service elements, CCR and TP. From here on each chapter discusses a major application area - OSI Network Management (Chapter 6), OSI Se- curity Architecture (Chapter 7), X.400 Message Handling (Chapter 8), X.500 Directory Services (Chap- ter 9), FTAM (Chapter 10), VT (Chapter 11), MAP (Chapter 12)

and JTM (Chapter 13). The treat- ment within these various chapters is

-very detailed and thorough, and will provide very useful information to those devoted and dedicated enough to wait for many of these good ideas to turn into real products on the market.

Altogether this is a very useful tutorial for those interested in OSI applications and related service elements. It extracts the pertinent information from all of the relevant OSI/CCITT standards, and presents them in a well-defined, clear and intelligent form.

Ray Hunt University of Canterbury

New Zealand

Authoritative and up to date book X.500: The Directory-Standard and its Application by Douglas Steedman, Technology Appraisals, UK, 1993, s 163 pp, ISBN 1871-8022-45

OSI has been called the largest standardization project ever under- taken, and the X.500 directory must rank as one of the most complex of all the OSI standards. So can a book which is a mere 130 pages long (excluding appendices) do justice to the standard? The author for many years chaired the CCITT directory group, and is thus uniquely qualified to write such a book. However, there is also a second question which must be asked. Given that the author is one of the leading technical experts on the subject, has he succeeded in writing a book which, in his own words, explains the standard 'without getting mired in the numerous details' and for which 'no prior knowledge' is needed?

Certainly the book is comprehen- sive, given its size. An introduction based on the requirements of a directory system rather than its

place in the OSI scheme of things is followed by an explanation of the basic concepts, including the roles of the DUA and DSA, and an intro- duction to the DIB and protocols. Further chapters are devoted to information, names, service, distri- bution, protocols, security, stan- d a r d s a n d a p p l i c a t i o n s . Throughout the book, the concepts are illustrated by means of a fictitious 'banana republic' and its 'top banana' Bill Paterson. The book seeks to cover both the 1988 and 1992 versions of the standard, and at various points seeks to explain the background to the development of the standard, and the relationship to X.400 work.

On the whole, explanations are clear, and are well supported by a glossary of terms and list of acro- nyms, although occasionally one is required to look at the glossary when a definition is not offered in the main text. The diagrams and tables are generally well presented, although there could have usefully been more of the former. The chapters on names (including distin-

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