Microsoft .NET

Microsoft took the lead in developing a framework that allows for developing a new generation of software. This framework melds computing and communications in an innovative way, offering developers the tools they need to transform the Web and every other aspect of the computing experience. Microsoft dubbed this framework, which relies and is built heavily on the use of the XML, .NET (dot Net) framework.

For the first time a framework exists that allows developers, businesses, and consumers to harness technology on their terms. The creation of truly distributed Web Services that will integrate and collaborate with a range of complementary services to serve customers in ways that today's dotcoms can only dream of is one of the foundations of .NET. Applications based on the .NET Framework can make information available at any time, in any place, and on any device.

Microsoft's innovative work with .NET resulted in a powerful message and platform for application development and deployment. We will go over many aspects of .NET within this book, so we will introduce you to its concepts here.

Back to Fundamentals

The fundamental idea behind the .NET Framework is that the focus is shifting from individual Web sites or devices connected to the Internet to constellations of computers, devices, and services that work together to deliver richer, broader solutions. People will control what, when, and how information is delivered to them. Computers, devices, and services will collaborate with each other to provide rich services instead of being isolated islands where the user provides the only integration. Businesses will offer their products and services in a way that lets customers seamlessly embed them in their own electronic fabric.

The .NET Framework will help drive a transformation in the Internet that will see HTML-based presentation augmented by programmable XML-based information.

The Software as a Service Approach

Programming models previously focused on a single system. Current object models like the Component Object Model (COM) and the Common Object Request Broker Architecture (CORBA) rely heavily on model-specific protocols such as Distributed COM (DCOM), Remote Method Invocation (RMI), or Internet Inter-Orb Protocol (IIOP) residing in a homogenous infrastructure. On the other hand, the .NET Framework is explicitly designed to allow the integration of any group of resources on the Internet into a single solution. Currently this type of integration is extremely complex and costly. The .NET Framework will make the integration and assembly of software services intrinsic to all software development projects.

The loosely coupled XML-based .NET programming model introduces the concept of creating XML-based Web Services. Whereas today's Web sites are handcrafted and don't work with other sites without significant additional development, the .NET programming model provides a built-in mechanism to build any Web site or service so that it will coalesce and collaborate seamlessly with others. Just as the introduction of interchangeable components accelerated the industrial revolution, the .NET Framework promises to hasten the development of software as a service.

Web Services

Broadly speaking, a Web Service is simply an application that can be integrated with other Web Services using Internet standards. In other words, it's a URL-addressable resource that programmatically returns information to clients who want to use it. One important feature of Web Services is that clients don't need to know how a service is implemented. The ability, or methods from a programming standpoint, are exposed and can be discovered using a specific process, which allows applications to be more dynamic and therefore require less attention as time goes on.

Like components, Web Services represent black-box functionality that can be reused without worrying about how the service is implemented. Web Services provide well-defined interfaces, called contracts, which describe the services provided. Developers can assemble applications using a combination of remote services, local services, and custom code. For example, a company might assemble an online store using the Microsoft Passport service to authenticate users, a third-party personalization service to adapt Web pages to each user's preferences, and a credit card processing service.

Unlike current component technologies, however, Web Services do not use object model-specific protocols such as DCOM, RMI, or IIOP as the set of participants in an integrated business process, and as technology changes over time, it becomes difficult to guarantee a single, unified infrastructure among all participants. Web Services take a different approach: they communicate using ubiquitous Web protocols and data formats such as HTTP and XML. Any system supporting these Web standards will be able to support Web Services.

Using XML within .NET

XML is the obvious choice for defining a standard yet extensible language to represent commands and typed data, and it's only appropriate that Windows .NET has adopted its use widely within its framework. While rules for representing commands and typed data using other techniques (such as encoding this information in a query string) could be defined, XML is specifically designed as a standard metalanguage for describing data. SOAP is an industry standard for using XML to represent data and commands in an extensible way. SOAP is being further developed at W3C under the name of XML Protocol (XMLP).

XML is the enabling technology for the Web Service contracts. The Service Contract Language (SCL) is an XML grammar for documenting Web Service contracts. Because SCL is XML-based, contracts are easy for both developers and developer tools to create and interpret. Microsoft is also a contributor to the Web Services Description Language (WSDL), recently submitted to W3C for further development (see http://www.w3.org/TR/2001/NOTE-wsdl-20010315). Standards like SOAP, SCL, and Discovery Protocol (DISCO), an XML-based format for Web Service discovery, help developers because they do not need to understand and implement different ways to access each Web Service they use.

Obviously, the advantages of the model are many. Companies can not only more easily integrate internal applications, but they can also access services offered by other businesses. By combining Web Services on the Internet, companies can create a wide variety of value-added applications.



XML Programming
XML Programming Bible
ISBN: 0764538292
EAN: 2147483647
Year: 2002
Pages: 134

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