- Email: [email protected]
A. Campbell, K. Nahrstedt: Building QoS into distributed systems. Chapman & Hall, 1997. ISBN 0-412-80940-0. 406 pages
Book reviews / Computer Communications 22 (1999) 491–494
described in the book and related to the computer communication networks. The back cover states that the book is aimed at ‘‘the computer and electrical engineers, who design and implement computer communication systems’’ and claims that the book covers all-aspects of modelling based performance evaluation. However, it describes only mathematical modelling in which models can be resolved by analytical or numerical means. There exist, however, another modelling approach, namely computer based modelling and simulation, which is a much more practical and popular method of evaluation of computer communication networks. In the book only few pages are devoted to the computer modelling and simulation. As a holder of master degrees in Computer Science and Electrical Engineering, as well as having several years of research experience in the area of performance evaluation of computer networks the convolution algorithm, conservation law, Petri nets, and stochastic models approach would not be my first choice when faced with the problem of performance studies in the evaluation of communication systems. My first choice to solve problems related to computer communications would be computer modelling and computer simulations. The predominant number of published papers in the mentioned areas are based on the results obtained using computer modelling and simulations, which proves that computer modelling and simulation is a practical and at least as an important approach in mathematical modelling. Additionally, reading the book I did not notice any attempts to mathematically model the data flow control related issues or treating data traffic as an aggregation of independently characterised data flows. The latter issues are very important when evaluating the performance of computer communication networks. In my opinion, one reference to Token Ring networks, one reference to Ethernet networks, one reference to ATM networks, and a few references to CPU task scheduling, memory paging and disc access, do not justify the strong relation to the computer communication systems being suggested in the book’s title. Hence, one may be misled by the title and the description on the back cover. In my opinion the title ‘‘An overview of performance evaluation methods with applications’’ would be more appropriate. As far as more detailed problems with the material presented in the book are concerned, there are a number of inconsistencies which I have indicated in the following paragraphs. On page 127, in the section describing round robin scheduling: ‘‘… For communication networks a similar approach can also be employed: large application packets from various sources are then split into minipackets (segmentation).’’ The process of segmentation is in fact performed in communication networks (e.g. on a network boundaries). Additionally, it is not a common approach to split packets when the round robin procedure is used. An
493
example network, where such technique is employed would certainly improve readability of the above comment. On page 132 in exercise 6.5 one can find the description of the following scenario. The voice call is said to convey 150 packets/s with 53B packets. This makes 7.95 Kb/s which is equivalent of 64 Kb/s load. This load is typical for an uncompressed voice, and hence the arrival time of data packets is more likely to be uniform, with constant intervals, rather than follow Poisson distribution. Throughout the book the approach used to describe data packet arrival times is based on Poisson distribution. This approach (as has been shown in a paper by Vern Paxton and Sally Floyd ‘‘Wide-Area Traffic: The failure of Poisson Modelling’’) is not adequate for this task. To conclude, the excellence of the book’s author is clearly visible in the field of systems performance evaluation, which is also proven by the long list of his publications. The book ‘‘Performance of computer communication systems’’ is a very well written and very well tailored course-book, and as such will certainly be an excellent basic reading for postgraduate students, studying the issues related to the system performance evaluation in general applications. Hence, with respect to the practical applications of knowledge presented in the book, the title and the back cover description are slightly misleading. Additionally, the book is aimed at a more specific readership than is indicated on the back cover. Also in my opinion the book is rather expensive (GBP60) and does not provide good value for the average higher education student. J. Wechta Communication Research Group, University of Wales, Singleton Park, Swansea SA2 8BB, UK E-mail address: [email protected] PII: S0140 -3 664(99)00025 -0
A. Campbell, K. Nahrstedt: Building QoS into distributed systems. Chapman & Hall, 1997. ISBN 0-412-80940-0. 406 pages. This is a book published by Chapman & Hall encapsulating the proceedings of the Fifth International Workshop on Quality of Service 1997 (IWQOS’97). As suggested in the Preface of the book, while many workshops and conferences offer technical sessions on the topic QoS, only IWQOS provides a single-track workshop dedicated to QoS research. Hence this book contains, in a single volume, a large number of technical papers reporting recent work on QoS. The book is organized into ten parts in accordance with the ten technical sessions held at IWQOS ‘97. They are, namely, Mobile Communication, Traffic Management,
494
Book reviews / Computer Communications 22 (1999) 491–494
QOS Routing, QOS and Video Systems, QOS Management, Distributed Object Computing, Advanced Reservation, QOS-based Transport Protocol, QOS Mapping and QOS Adaptation. Apart from the technical papers presented at the workshop, the book also includes the keynote address on ‘‘Programming Telecommunication Networks’’ given by Aurel A. Lazar of Columbia University, an invited talk on ‘‘Quality of Service: Where are We ?’’ presented by R. Steinmetz of Darmstadt University of Technology and L. C. Wolf of German National Research Center for Information Technology, and summaries of two panel discussions captioned ‘‘QoS for Distributed Object Computing Middleware—Fact or Fiction ?’’ and ‘‘Reservations about Reservations’’. In addition, the book contains a chapter captioned ‘‘Workshop Summary’’, which gives an excellent introduction to the various parts of the book. The book will be useful for readers who want to know more about the issues, possible solutions and future direction with regard to QoS in distributed systems. It will be a good resource book for postgraduate students and researchers who have just embarked on some research projects on both QoS and distributed systems, and engineers and software developers who need to design or write software for distributed systems which will have the ability to control the
service quality for those applications they are designed to support. It will also be a good reference book for researchers who have been active in QoS and distributed system research. Although the book contains essentially a collection of technical papers and summaries written by different authors, the flow is generally smooth. The book is easy and interesting to read because, in line with the workshop theme and book caption ‘‘Building QoS into Distributed Systems’’, most papers chose to focus on results, discussion and sharing of innovative ideas rather than to present complex theories and mathematical proofs. Priced at GBP79.95, this book is expensive for any individual who just wants to use it as a reference. Nevertheless, it is a good collection for any library, research group and project team. T.H. Cheng Network Technology Research Centre, Nanyang Technological University, School Electrical/Electronic Eng., Nanyang Avenue, Singapore 639798, Singapore PII: S0 140-3664(99 )00 027-4
described in the book and related to the computer communication networks. The back cover states that the book is aimed at ‘‘the computer and electrical engineers, who design and implement computer communication systems’’ and claims that the book covers all-aspects of modelling based performance evaluation. However, it describes only mathematical modelling in which models can be resolved by analytical or numerical means. There exist, however, another modelling approach, namely computer based modelling and simulation, which is a much more practical and popular method of evaluation of computer communication networks. In the book only few pages are devoted to the computer modelling and simulation. As a holder of master degrees in Computer Science and Electrical Engineering, as well as having several years of research experience in the area of performance evaluation of computer networks the convolution algorithm, conservation law, Petri nets, and stochastic models approach would not be my first choice when faced with the problem of performance studies in the evaluation of communication systems. My first choice to solve problems related to computer communications would be computer modelling and computer simulations. The predominant number of published papers in the mentioned areas are based on the results obtained using computer modelling and simulations, which proves that computer modelling and simulation is a practical and at least as an important approach in mathematical modelling. Additionally, reading the book I did not notice any attempts to mathematically model the data flow control related issues or treating data traffic as an aggregation of independently characterised data flows. The latter issues are very important when evaluating the performance of computer communication networks. In my opinion, one reference to Token Ring networks, one reference to Ethernet networks, one reference to ATM networks, and a few references to CPU task scheduling, memory paging and disc access, do not justify the strong relation to the computer communication systems being suggested in the book’s title. Hence, one may be misled by the title and the description on the back cover. In my opinion the title ‘‘An overview of performance evaluation methods with applications’’ would be more appropriate. As far as more detailed problems with the material presented in the book are concerned, there are a number of inconsistencies which I have indicated in the following paragraphs. On page 127, in the section describing round robin scheduling: ‘‘… For communication networks a similar approach can also be employed: large application packets from various sources are then split into minipackets (segmentation).’’ The process of segmentation is in fact performed in communication networks (e.g. on a network boundaries). Additionally, it is not a common approach to split packets when the round robin procedure is used. An
493
example network, where such technique is employed would certainly improve readability of the above comment. On page 132 in exercise 6.5 one can find the description of the following scenario. The voice call is said to convey 150 packets/s with 53B packets. This makes 7.95 Kb/s which is equivalent of 64 Kb/s load. This load is typical for an uncompressed voice, and hence the arrival time of data packets is more likely to be uniform, with constant intervals, rather than follow Poisson distribution. Throughout the book the approach used to describe data packet arrival times is based on Poisson distribution. This approach (as has been shown in a paper by Vern Paxton and Sally Floyd ‘‘Wide-Area Traffic: The failure of Poisson Modelling’’) is not adequate for this task. To conclude, the excellence of the book’s author is clearly visible in the field of systems performance evaluation, which is also proven by the long list of his publications. The book ‘‘Performance of computer communication systems’’ is a very well written and very well tailored course-book, and as such will certainly be an excellent basic reading for postgraduate students, studying the issues related to the system performance evaluation in general applications. Hence, with respect to the practical applications of knowledge presented in the book, the title and the back cover description are slightly misleading. Additionally, the book is aimed at a more specific readership than is indicated on the back cover. Also in my opinion the book is rather expensive (GBP60) and does not provide good value for the average higher education student. J. Wechta Communication Research Group, University of Wales, Singleton Park, Swansea SA2 8BB, UK E-mail address: [email protected] PII: S0140 -3 664(99)00025 -0
A. Campbell, K. Nahrstedt: Building QoS into distributed systems. Chapman & Hall, 1997. ISBN 0-412-80940-0. 406 pages. This is a book published by Chapman & Hall encapsulating the proceedings of the Fifth International Workshop on Quality of Service 1997 (IWQOS’97). As suggested in the Preface of the book, while many workshops and conferences offer technical sessions on the topic QoS, only IWQOS provides a single-track workshop dedicated to QoS research. Hence this book contains, in a single volume, a large number of technical papers reporting recent work on QoS. The book is organized into ten parts in accordance with the ten technical sessions held at IWQOS ‘97. They are, namely, Mobile Communication, Traffic Management,
494
Book reviews / Computer Communications 22 (1999) 491–494
QOS Routing, QOS and Video Systems, QOS Management, Distributed Object Computing, Advanced Reservation, QOS-based Transport Protocol, QOS Mapping and QOS Adaptation. Apart from the technical papers presented at the workshop, the book also includes the keynote address on ‘‘Programming Telecommunication Networks’’ given by Aurel A. Lazar of Columbia University, an invited talk on ‘‘Quality of Service: Where are We ?’’ presented by R. Steinmetz of Darmstadt University of Technology and L. C. Wolf of German National Research Center for Information Technology, and summaries of two panel discussions captioned ‘‘QoS for Distributed Object Computing Middleware—Fact or Fiction ?’’ and ‘‘Reservations about Reservations’’. In addition, the book contains a chapter captioned ‘‘Workshop Summary’’, which gives an excellent introduction to the various parts of the book. The book will be useful for readers who want to know more about the issues, possible solutions and future direction with regard to QoS in distributed systems. It will be a good resource book for postgraduate students and researchers who have just embarked on some research projects on both QoS and distributed systems, and engineers and software developers who need to design or write software for distributed systems which will have the ability to control the
service quality for those applications they are designed to support. It will also be a good reference book for researchers who have been active in QoS and distributed system research. Although the book contains essentially a collection of technical papers and summaries written by different authors, the flow is generally smooth. The book is easy and interesting to read because, in line with the workshop theme and book caption ‘‘Building QoS into Distributed Systems’’, most papers chose to focus on results, discussion and sharing of innovative ideas rather than to present complex theories and mathematical proofs. Priced at GBP79.95, this book is expensive for any individual who just wants to use it as a reference. Nevertheless, it is a good collection for any library, research group and project team. T.H. Cheng Network Technology Research Centre, Nanyang Technological University, School Electrical/Electronic Eng., Nanyang Avenue, Singapore 639798, Singapore PII: S0 140-3664(99 )00 027-4