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Relational Information Systems
Theoryof systems integration Integrating Data Processing Systems In Theoty and In Practice by W H Inmon. Published by PrenticelHall. 264~~. M8.50. Integration of systems is a desirable, and in certain cases an essential, objective. For this book’s author it is approaching a mission with immense benefits if it is achieved and a ‘chaotic environment’ with diminishing productivity if it is not. The term in the title ‘in practice’ might indicate that the limitations of applying the theoretical approach to practical situations was explored. This is not so. The references to practice are generally derogatory, suggesting an inadequate understanding and application of sound systems design principles. So the opportunity is not taken to identify the valid reasons why so few organizations have achieved total integration and even when they have, why it is often not maintained. No distinction is drawn between certain groupings of application which are based on a high level of common data where integration is
essential and others where considerations such as the scheduling of developments, changing corporate strategies, the exploitation of new and more advanced hardware and software products compete for priority with integration. The author acknowledges that the means of achieving systems integration is elusive and anything but obvious. The subject is treated on a conceptual level with separate consideration of physical and logical integration. The scope extends to cover centralized and decentralized systems, initial and ongoing integration and the specific problems raised by systems’ ownership, changes and large accumulation of data. The material is thought-provoking and creates a new perspective for reconsidering the problems of defining an overall systems strategy removed for the day to day requirements of individual systems developments. There is a big gap between the material and its application. It has similarities with some of the established methods of
data analysis but no reference is made to other published work. This leaves an uncertainty as to whether the intention was to develop and extend existing methodologies or to derive a new methodology from first principles. The production is to a high standard with clear headings and welldrawn diagrams. One interesting feature is a set of very searching questions at the end of each chapter. These questions are not ones to which careful reading of the text will provide a full answer. They are rather the questions which are raised by the material in the chapter the answers to which, when determined, would give greater insight to the solution to the problems considered. The issues in the book are important ones now and for the future. They are worth spending time considering in spite of the limitations of the approach adopted. ADRIAN LEPPER The Open University
Advancedrelationaldatabasetheory Relational Information Systems by T H Met-ret. Published by Reston. SO7pp. X28.45. There is a definite need for a book like this. It provides a practical guide to advanced relational database theory. In this respect it scores well over many published papers on the subject, which have tended to give little pragmatic help. It is oriented toward rather than ‘use’, ‘implementation’ although ‘use’ is well covered. In this respect it will be a valuable handbook for advanced users as well as implementers. The subject is covered thoroughly and in considerable depth without losing it’s practical base. The subject matter is covered quickly, so much so that the text can sometimes be a little confusing, but nonetheless
42
it is easy to read. There is a plethora of illustrations and examples, which in themselves recommend the book. Wherever the work of other researchers is drawn upon, the appropriate references are mentioned immediately in the text, along with a brief summary of the content of the reference. This is an excellent practice which should be encouraged. The book has one failing. The practice of embedding student exercises in the text can be rather frustrating for the professional reader. Such exercises should always be held to the end of the book, if they are included at all. There are two case studies, both of which are invented. However, they
are explained in considerable detail and the reader is left in no doubt about how the system works. To summarize, this book provides a valuable and practical guide to the complex and rarified world of advanced relational database theory. It does not pretend that relational database theory is simple, as do so many other texts. Instead it thoroughly explains the theory, so that the user can grasp the more mathematical aspects. Any systems analyst who is contemplating the use of relational systems would do well to buy a copy of this book.
RUPERT University
HARPER of Sussex
data processing
essential and others where considerations such as the scheduling of developments, changing corporate strategies, the exploitation of new and more advanced hardware and software products compete for priority with integration. The author acknowledges that the means of achieving systems integration is elusive and anything but obvious. The subject is treated on a conceptual level with separate consideration of physical and logical integration. The scope extends to cover centralized and decentralized systems, initial and ongoing integration and the specific problems raised by systems’ ownership, changes and large accumulation of data. The material is thought-provoking and creates a new perspective for reconsidering the problems of defining an overall systems strategy removed for the day to day requirements of individual systems developments. There is a big gap between the material and its application. It has similarities with some of the established methods of
data analysis but no reference is made to other published work. This leaves an uncertainty as to whether the intention was to develop and extend existing methodologies or to derive a new methodology from first principles. The production is to a high standard with clear headings and welldrawn diagrams. One interesting feature is a set of very searching questions at the end of each chapter. These questions are not ones to which careful reading of the text will provide a full answer. They are rather the questions which are raised by the material in the chapter the answers to which, when determined, would give greater insight to the solution to the problems considered. The issues in the book are important ones now and for the future. They are worth spending time considering in spite of the limitations of the approach adopted. ADRIAN LEPPER The Open University
Advancedrelationaldatabasetheory Relational Information Systems by T H Met-ret. Published by Reston. SO7pp. X28.45. There is a definite need for a book like this. It provides a practical guide to advanced relational database theory. In this respect it scores well over many published papers on the subject, which have tended to give little pragmatic help. It is oriented toward rather than ‘use’, ‘implementation’ although ‘use’ is well covered. In this respect it will be a valuable handbook for advanced users as well as implementers. The subject is covered thoroughly and in considerable depth without losing it’s practical base. The subject matter is covered quickly, so much so that the text can sometimes be a little confusing, but nonetheless
42
it is easy to read. There is a plethora of illustrations and examples, which in themselves recommend the book. Wherever the work of other researchers is drawn upon, the appropriate references are mentioned immediately in the text, along with a brief summary of the content of the reference. This is an excellent practice which should be encouraged. The book has one failing. The practice of embedding student exercises in the text can be rather frustrating for the professional reader. Such exercises should always be held to the end of the book, if they are included at all. There are two case studies, both of which are invented. However, they
are explained in considerable detail and the reader is left in no doubt about how the system works. To summarize, this book provides a valuable and practical guide to the complex and rarified world of advanced relational database theory. It does not pretend that relational database theory is simple, as do so many other texts. Instead it thoroughly explains the theory, so that the user can grasp the more mathematical aspects. Any systems analyst who is contemplating the use of relational systems would do well to buy a copy of this book.
RUPERT University
HARPER of Sussex
data processing