Martin Kalin - Java Web Services: Up and Running

In the four years or so since the first edition, there has been continuity as well as change.Web services remain a popular and arguably even dominant approach toward distributed software systems that is, systems that require the interaction of softwareon physically distinct devices. The Web itself is a prime example of a distributed system, and thecurrent trend is to blur the distinction between traditional, HTML-centric websites andmodern web services , which typically deliver XML or JSON payloads instead of HTML ones.Web servicesare an appealing way to create distributed systems because these services can piggyback on existing infrastructure suchas HTTP(S) transport, web servers, database systems, modern programming languages of various stripes, widespreadsoftware libraries for JSON and XML processing, security providers, and so on. Indeed, web services are a lightweight and flexibleway to integrate divergent software systems and to make the functionality of such systems readily accessible.

Java remains a major player in web services, and Java support for these services, in the form ofstandard and third-party software libraries and utilities, continues to improve. Yet two importantand related shifts in emphasis have occurred since this book was first published:

The two changes in web services are reflected in how the second edition is organized. begins with an overview of webservices, including the link between such services and Service-Oriented Architecture (SOA), and the chapterincludes a code-based contrast of SOA and the competing Distributed Object Architecture (DOA). The discussion thenturns to REST: what the acronym means, why HTTP can be treated as an API and not just a transport, and how the RESTfulmindset continues to impact the design and implementation of modernweb services. The first chapter includes sample HTTP clients in Java, clients that can be targeted at either websitesor web services.The first chapterends with a RESTful service implemented as a JSP script withsupport from two backend POJO classes; the service is published with the Tomcat web server. The first chapter goes into thedetails of installing and running Tomcat; the second chapter does the same for the Jetty web server. The aforementionedAnt script is also clarified so that the sample web services can be packaged and deployed automatically.

Although this edition ofthe book starts with REST-style services, SOAP-based services are treated thoroughly. is dedicatedto practical web security, from wire-level security through users/roles security up to WS-Security.