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Reviewer: Julia E. Hodges

The authors describe this edition as a reflection of the technological changes and advances that have occurred since the first edition was published in 2008. The concept for this book grew from the authors" opinion that people in certain industries (for example, healthcare, life sciences, engineering, and national intelligence) suffer from a lack of introductory-level training on the capabilities of semantic Web languages such as the Web ontology language OWL. The authors created a training series for Web developers, and their experience with this training convinced them that Web practitioners need introductory-level educational materials that they can study on their own and refer to repeatedly. The second edition of the book retains the flavor of the first edition in that it begins with the basics--it defines the semantic Web and discusses the available tools for working with it--and then goes on to discuss the use of ontologies. Chapter 1 provides the motivation for the development of the semantic Web, explaining how it quickly overcame early skepticism that no one would be interested in providing all the content needed for a distributed web of information on many different topics. The second chapter approaches the subject of semantic modeling by first talking about the modeling of human communication, with an emphasis on the abilities of such models to provide explanations, make predictions, and represent the common points among different viewpoints. The point that is made is that modeling information on the semantic Web is "the activity of distilling communal knowledge out of a chaotic mess of information." The use of the resource description framework (RDF) as a semantic Web representation language is covered in chapter 3. Several examples, with accompanying figures, show how RDF can model data, including how that data is distributed and merged on the Web. The next chapter, expanding on the data modeling discussion in chapter 3, describes the architecture of Web applications (with components such as parsers and query engines). Querying the Web is discussed in chapter 5. Several examples illustrate the different types of information retrieval systems. There is an emphasis on the use of SPARQL as both a query and a rule language. Chapter 6 introduces the concept of inferencing. More details are provided in chapters 7 to 12, which cover RDF, RDF Schema Plus (RDFS-Plus), simple knowledge organization system (SKOS), and OWL. Chapter 13, "Ontologies on the Web--Putting It All Together," describes the GoodRelations ontology; QUDT, the NASA ontology for units of measure; and CHEBI, for biological ontologies. Chapter 15 covers more advanced concepts of modeling in OWL; it includes brief descriptions of metamodeling, multi-part properties, profiles, and rules, but only at the level of introducing the concepts. Chapter 14, "Good and Bad Modeling Practices," includes a number of examples that can result in poorly designed, unusable data models. Some of the design practices described here (such as "know what you want" and "modeling for reuse") reflect well-accepted software engineering design principles. The chapter ends with examples of common errors made in Web models. Chapter 16, "Conclusions," is a brief overview of the book's major concepts. It is followed by a useful appendix of frequently asked questions, with references to those pages that cover the challenges associated with each question. Overall, this is an easy-to-follow guide to the basic concepts related to building semantic Web ontologies. The book flows well from chapter to chapter, and the many examples illustrate the different topics. For beginners, it's an excellent introduction to the subject, which is exactly what the authors intended; however, for more experienced practitioners, the book is not as useful. Online Computing Reviews Service

Reviewer: David E. Robbins

Anyone who is interested in semantic Web technologies will find this book deeply instructive. Although written at an introductory level, even experienced semantic modelers and application builders will find Allemang and Hendler's lucid descriptions and relevant examples to be a refreshing and enlightening review of the core of the semantic Web. Chapters 1 and 2 provide the philosophical concepts necessary to understand the architecture of the semantic Web. Chapter 2 also links the semantic Web to more traditional data modeling schemes, such as relational databases. Chapter 3 introduces the resource description framework (RDF), the fundamental standard of the semantic Web. The overall architecture of a semantic Web application is described in chapter 4. Chapters 5 and 6 describe SPARQL, the semantic Web query language, and inferencing, a key use of SPARQL. One remarkable feature of this book is the use of SPARQL to describe all of the algorithms (an update from the first edition). Chapters 7 to 15 cover data modeling. Allemang and Handler describe the data modeling standards available to working ontologists in order of increasing expressiveness: RDF schema (RDFS) (chapter 7), RDFS-Plus (chapters 8 to 10), and the Web ontology language (OWL) (chapters 11, 12, and 15). In chapters 13 and 14, advice is given for tying together the modeling standards and making use of best practices for representing data in the semantic Web. Chapter 16 provides concluding remarks. Readers may note a few errors in the output given for example code (for example, queries that should return two values only returning one). Although significant, these errors do not detract from the overall quality of the book. The descriptions of the code samples and the expected output are good enough to allow for the easy detection of any errors. The overlap of terminology between the fields of object-oriented programming and the semantic Web (for example, classes and properties) sometimes leads to confusion. Readers moving into semantic Web programming from an object-oriented background will find the sidebars especially helpful in clarifying these points of difference. Overall, this book provides a thorough and cogent introduction to the semantic Web. Giving just enough philosophical background, the authors focus on the practical aspects of constructing data stores and applications. This blend of philosophy and practical descriptions leads the reader to anticipate how the standards of the semantic Web should work before the standards are described. As a result, the reader is likely to feel that the semantic Web works just as it should. Online Computing Reviews Service