Web Data APIs for Knowledge Graphs: Easing Access to Semantic Data for Application Developers

Description

This book describes a set of methods, architectures, and tools to extend the data pipeline at the disposal of developers when they need to publish and consume data from Knowledge Graphs (graph-structured knowledge bases that describe the entities and relations within a domain in a semantically meaningful way) using SPARQL, Web APIs, and JSON. To do so, it focuses on the paradigmatic cases of two middleware software packages, grlc and SPARQL Transformer, which automatically build and run SPARQL-based REST APIs and allow the specification of JSON schema results, respectively. The authors highlight the underlying principles behind these technologies--query management, declarative languages, new levels of indirection, abstraction layers, and separation of concerns--, explain their practical usage, and describe their penetration in research projects and industry. The book, therefore, serves a double purpose: to provide a sound and technical description of tools and methods at the disposal of publishers and developers to quickly deploy and consume Web Data APIs on top of Knowledge Graphs; and to propose an extensible and heterogeneous Knowledge Graph access infrastructure that accommodates a growing ecosystem of querying paradigms. Foreword by Tobias Kuhn Preface Acknowledgments Knowledge Graphs of Linked Data Knowledge Graphs and Linked Data RDF: Resource Description Framework SPARQL: SPARQL Protocol and RDF Query Language GraphQL: Web API Made Easy Accessing Knowledge Graphs Programmatically Querying Knowledge Graphs HTTP Requests SPARQL Libraries Manipulating SPARQL's Output Web Data APIs Over SPARQL REST APIs The OpenAPI Specification Writing Web APIs Writing Knowledge Graph APIs Limitations of Knowledge Graph APIs Repetitive Work Query Management Controlling Results grlc: API Automation by Query Sharing Overview Architecture Working with grlc Features Query Documentation Query Variables Query Execution Query Result Manipulation Exercises Shaping JSON Results: SPARQL Transformer SPARQL Results JSON Format: The Curse of the Bindings Data Reshape with SPARQL Transformer A Single JSON Object as Query and Template Architecture Features and Syntax Merging Around an Anchor Overview of $-Modifiers Dealing with Languages A Complete Example grlc and SPARQL Transformer Exercises Applications grlc Linked Data Platform for Genetics Research Nanopublications CLARIAH and Social History Research TNO: FoodCube NewGen Chennai: Conference Proceedings EU RISIS: Science, Technology, and Innovation SPARQL Transformer KG Explorer FADE grlc and Transformer Demos/Links Conclusion and Future Challenges Solutions Chapter 4 Chapter 5 Bibliography Authors' Biographies Blank Page