This is a book about the OMG's POS (persistent object services) standard, a standard specifying interfaces through which objects can be saved and loaded with datastore independence. The author was an architect of IBM's submission when, in the early nineties, the OMG put out a request for proposals for a persistent object service specification. The book is aimed at anyone who wants an overview of the POS standard, but doesn't want to get into the technicalities of the standard specification.

Coverage is comprehensive, from a historical narrative of the events leading up to the adoption of the standard, to a chapter covering issues of interest to datastore vendors. The book does not limit itself to POS, but covers other issues relevant to the OMG view of objects such as the object life cycle, trans-actions and security. The explanations are accompani-ed by plenty of sample code, most of it in C.

One of the largest chapters is the chapter on the OMG's interface definition language (IDL). IDL is a language designed not for programming, but for specifying object interfaces independently of programming language. Knowledge of IDL is a pre-requisite to the study of any OMG specification and this comprehensive chapter may justify the purchase of the book. There are many examples of how the IDL code translates into C, leaving blanks for the programmer to fill in.

I enjoyed this book. I found it informative and easy to read.