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This book covers the nitty gritty of JAX-RS: a Java based standard (specification) for building RESTful web services. It covers JAX-RS 2.1 (the latest edition) and can be used as a cheat sheet or a getting started with JAX-RS style guide.
The contents of this book are divided into distinct sections which cover the bare basics, core components and some of the advanced framework features as well. Here is an overview
JAX-RS 2.1 (latest addition) - Server Sent Events, JSON-B integration, Reactive Client API etc.
Core: resources, annotations, HTTP method dispatch, injection
Providers: message body readers & writers, filters, interceptors, exception mappers
Advanced: request processing pipeline, method matching, caching, content negotiation
Other topics: Asynchronous processing, Client API, Security