O'Reilly and Associates, Inc. publishes an entire series of books on Java programming. You can find a complete list of Java books from O'Reilly and Associates at http://java.oreilly.com. Books that are of particular interest to Java developers working with web services include:
- Java in a Nutshell by David Flanagan
A Java language tutorial and complete API reference for the core Java classes.
- Java Enterprise in a Nutshell by Jim Farley, William Crawford, and David Flanagan
A tutorial and API reference for many of Java's enterprise API's, including EJBs and servlets, both of which can be used to host Java web services.
- Java and XML by Brett McLaughlin
Although it is possible to create and use simple web services without much understanding of XML, a proper grounding in this important subject is required to make use of the more advanced features. Brett McLaughlin's Java and XML provides both an introduction to XML and good coverage of many of the XML-based technologies that are relevant to web services.
- XML Schema by Eric van der Vlist
This book provides detailed coverage of the XML schema language, a knowledge of which is useful if you want to be able to read web service definitions written using WSDL, or if you intend to use the lower-level web service APIs, such as SAAJ.
- Ant: the Definitive Guide by Jesse Tilly and Eric M. Burke
Provides comprehensive coverage of Ant , which is now the tool that is most commonly used by development teams to build their software, and which is required to compile and run the example source code for this book.
Web Services Programming Resources Online
This book is a quick reference designed for speedy access to frequently needed information. It does not, and cannot, tell you everything you need to know about developing web services in Java. In addition to the books just listed, there are several valuable (and free) electronic sources of information about web services:
- The World Wide Web Consortium (W3C) web site
Although much of the existing technology underpinning web services was developed independently by groups of companies such as Sun Microsystems, IBM, and Microsoft working together, most of those technologies have now been adopted and are being standardized by the W3C. You can find the latest drafts of the specifications currently being worked on, plus technical reports that document the earlier work, including the specifications for SOAP and WSDL, on the W3C web site at http://www.w3c.org.
- The OASIS web site
The Organization for the Advancement of Structured Information Standards (OASIS) is a not-for-profit organization that is leading the development of standards in the e-business arena. OASIS is one of the sponsors for ebXML, which uses SOAP as its underlying message transport mechanism, and is also undertaking web service- related work in the areas of distributed management, interactive applications, reliable messaging, and services for remote portals. You can find the current state of this work at http://www.oasis- open .org.
- Web Services Interoperability Organization (WS-I) web site
WS-I is a relatively new organization whose aim is to promote cross-platform web service interoperability by defining profiles that reduce the number of choices that web service vendors need to make when creating their infrastructure. Sun recently announced that the web service support in J2EE 1.4 conforms to the WS-I Basic Profile Version 1.0, which covers the construction of SOAP messages, WSDL documents, and service publication in XML-based registries. The WS-I web site is at http://www.ws-i.org.
- Apache Web Services Project web site
The Apache Software Foundation has a project dedicated to web services, the web site of which can be found at http://ws.apache.org. Apache Axis, which can be downloaded from this site, is an implementation of SOAP that claims to comply to both the JAX-RPC 1.0 and SAAJ 1.1 specifications and can therefore be used as an alternative to Sun's reference implementations of these APIs. There is also an implementation of WS-Security, a W3C standard that is not currently part of either J2EE 1.4 or the JWSDP.
- XMethods web site
The XMethods web site at http://www.xmethods.com provides links to many publicly available demonstration web services, some of which also have example clients that you can use to try out the service or see how to use it.