Sebastopol, CA-Web services, new darling of the technology media, still escapes concrete definition. Ethan Cerami, author of the just-released Web Services Essentials (O'Reilly, US $29.95), is firm about his definition, however: "At a minimum, a web service is any piece of software that makes itself available over the Internet and uses a standardized XML messaging system. Web services currently run a wide gamut from news syndication and stock-market data to weather reports and package-tracking systems."
Web services are being used in a growing variety of network programming and information publishing situations. Web services are also at the core of Microsoft's new .NET strategy, Sun Microsystems's Sun One Platform, and the W3C's XML Protocol Activity Group. A Web Services Interoperability Organization has just been formed. Pundits are touting the potential of web services software, and predicting that sales are poised to explode. With so much attention focused on this new breed of distributed services, web developers are eagerly entering the virtual arena.
Cerami is already an old hand at this emerging technology. "I think web services represent an important evolutionary step in building distributed applications," says Cerami. "So, what is really new about web services? The answer is XML. XML lies at the core of web services, and provides a common language for describing Remote Procedure Calls, web services, and web service directories. Prior to XML, one could share data among different applications, but XML makes this so much easier to do. In the same vein, one can share services and code without web services, but XML makes it easier to do these as well. By standardizing on XML, different applications can more easily talk to one another, and this makes software a whole lot more interesting."
Web services represent an evolving set of standards that will enable diverse and occasionally obstreporous applications to more easily discover each other and seamlessly exchange data via the Internet. For instance, programs written in Java and running on Solaris can find and call code written in C# that run on Windows XP, or programs written in Perl that run on Linux, without any concern about the details of how that service is implemented. As a developer new to web services, how do you make sense of this emerging framework so you can start writing your own services today? Web Services Essentials arms programmers with both a concise, concrete introduction, and a handy reference to XML web services, first by explaining the foundations and capabilities, and then by demonstrating quick ways to create services with open-source Java tools.
In Web Services Essentials, author Ethan Cerami explores four key emerging technologies and how they fit together in the web services landscape: XML Remote Procedure Calls (XML-RPC), SOAP (the foundation for most commercial web services development), Universal Discovery, Description and Integration (UDDI), and Web Services Description Language (WSDL). The book provides a quick overview of each topic, Java tutorials with sample code, samples of the underlying XML documents, and explanations of freely-available Java APIs. Cerami includes a guide to the current state of web services, pointers to open-source tools, and a comprehensive glossary of terms. Cerami also demonstrates the core protocols, showing developers how they interact and how best to apply them to particular web service situations. Demonstrations are written primarily in Java, with other languages used to demonstrate interoperability. Web Services Essentials is the only book to cover web services from a vendor-neutral perspective.
Web Services Essentials meets a pressing need for resources that show how the many different parts of the web services puzzle fit together, and gives developers a clearer view of the emerging technology. This book will get you started building web services quickly by providing big picture context as well as real coding examples in a single volume. "Web services gets too much hype these days," concludes Cerami. "This book doesn't make any grand claims about web services. Rather, it shows what web services can do today. As such, I hope it gives readers an idea of the field, and provides some hints on where it may go in the future."
Additional resources:
Web Services
Essentials
Distributed Applications with XML-RPC, SOAP, UDDI & WSDL
By Ethan Cerami
February 2002
0-596-00224-6, Order Number: 2246
288 pages, $29.95 (US), $44.95 (CA)
order@oreilly.com
1-800-998-9938
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