Foreword

Looking back at the last 30 years of human-computer interaction, a number of key milestones stand out prominently: the shift from the mainframe computing to the PC, the introduction of the graphical user interface, the move from 16- to 32-bit processors, and most recently, the pervasiveness of the Internet and the Web. Each of these landmarks represents a fundamental turning point in the relationship between human and machine. They also served to address some of the most pressing industry challenges of the time, from providing a viable platform for consumer-based computing to satisfying the need for richer, graphical user interaction to enabling ubiquitous application deployment and access.

Now, as businesses seek to address the ongoing fundamental challenges of software integration, a new technology called XML Web services is promising to once again fundamentally transform and enhance the way consumers and businesses interact with computers. The core concept behind these Web services is relatively straightforward[md]components that are accessible using standardized Internet protocols. Yet their potential to affect the industry is both far-reaching and profound. Similar to computing revolutions of the past, XML Web services represents a new paradigm around which the entire computing industry is converging. Partners and competitors alike are quickly recognizing the value of XML Web services as a universal component architecture[md]one that spans programming languages, networks, and even platforms.

But why this sudden move to a new software integration paradigm when technologies such as DCOM and CORBA already exist? Although they provide a viable option for integration of systems residing in a uniform corporate Intranet, they lack the capability to adapt to the loosely coupled, heterogeneous environment of the Internet. As this became evident to more and more businesses that required integration not only within the firewall, but also with diverse business partners and customers, it became clear that the path to success lay not in tightly-coupled, proprietary systems, but in the adoption of integration technologies based on open standards. This is the fundamental differentiator and the key to the success of Web services.

For developers, Web services present a nearly limitless world of new opportunities. Because of the fundamental issues they address, Web services are pertinent to the entire spectrum of today's software, from rich Windows applications, to thin-client Web applications to the emerging market of mobile device software. For Visual Basic developers, Web services represent a new era in component creation and reuse. From day one, Visual Basic developers have been avid consumers of preexisting components. With XML Web services, the ability to consume components is vastly expanded to the Internet, across firewalls and even to other operating systems. And with Visual Basic .NET, the ability to call this remote functionality is as easy as setting a reference to an existing COM component in VB 6.0. Building XML Web services in Visual Basic .NET is just as effortless. In fact, if you've ever written a class in Visual Basic 6, you're well on your way to creating Web services that can be deployed locally, on your corporate Intranet, or on the Internet itself.

In Creating and Consuming Web Services in Visual Basic, the authors cover the basics of XML Web service construction and consumption as well as numerous advanced topics associated with Web-service development. Their practical approach to describing the concepts of Web services will have you up and running in the first chapter. From there, you'll discover and implement Web services that address pertinent issues of security, state management, and asynchronous calls as well as the ever-important bottom line: how Visual Basic .NET and XML Web services can save your business money, promote integration with business partners and customers, and reduce your project's time to market.

As we enter a new era in component development and reuse, Visual Basic .NET and XML Web services empower us as VB developers to continue to be on the cutting edge of application development. And with this book, you've already taken the first step to understanding and implementing these crucial components that will take our Visual Basic applications to the next level.

Ari Bixhorn
Product Manager
Visual Basic .NET
Microsoft Corporation