.NET Technologies

All editions of Windows Server 2003 include IIS 6 and ASP.NET and support the Windows .NET Framework. IIS, as you probably already know, is a bundle of essential Web services that allow servers to act as Web servers, File Transfer Protocol (FTP) servers, Simple Mail Transfer Protocol (SMTP) hosts, and Network News Transfer Protocol (NNTP) hosts. ASP.NET is a server-side scripting environment for developing Web applications. The Windows .NET Framework is an application development environment that defines framework classes and application processes to simplify the development and deployment of Internet applications— and this is where things get really interesting.

.NET Framework Technologies

By using the .NET Framework, isolated applications can be transformed into online services that can be worked with over the Internet or in intranet environments, allowing users to access the services regardless of where the users are located. Windows Server 2003 exists within this framework, and the capabilities of the framework form the underpinnings of the operating system. Anything you can do with the Windows operating system on the corporate network, you can do over the Internet as well.

The concepts underlying the Windows .NET Framework are industry-standard technologies, including the following:

  • Extensible Markup Language (XML) A language that can be used to describe other languages and to give form and structure to abstract data concepts. You give data concepts form by describing their components and the relationship between the components. For example, the concept of a customer could be represented by using name, address, phone number, account number, and purchase history components.

    Note

    For more information about XML and related technologies, I recommend reading XML Pocket Consultant (Microsoft Press, 2002).

  • Simple Object Access Protocol (SOAP) A technology that facilitates message exchange in distributed environments, allowing XML-formatted information to be exchanged over the Internet or an intranet. The messages exchanged can include general requests and responses to requests.

  • Universal Description, Discovery, and Integration (UDDI) A standard that makes it possible to locate and discover information about XML-based Web services. By using UDDI, an application can locate an available service and then discover information about it.

  • Web Service Description Language (WSDL) A language that can be used to describe XML-based Web services. By using WSDL, function names, required parameters, and returned results from an XML-based Web service can be published so that they can be discovered through UDDI.

For organizations looking to develop Web-based applications, these technologies make it possible to create online services that communicate with each other, learn about new Web services that might become available, and then use a discovery process to structure messages properly so communication exchange is possible.

.NET Framework Layers

The Windows .NET Framework has three main layers:

  • Common language runtime engine—The bottom layer Handles low-level services, such as verification of type safety, memory management for managed objects, and exception handling. You can think of it as a virtual machine that resides at the bottom of the framework and handles essential functions.

  • Common class library—The middle layer Provides the common classes for the runtime engine. It includes system classes for building components, user interface creation, and input/output (I/O); enabling classes that use SOAP, UDDI, and WSDL for communications exchange; and support classes for code compilation and generation.

  • ASP.NET—The top layer Provides the server-side scripting environment that can be used to develop Web applications. It includes server controls for working with Web forms, event-handling components, application state and session state management facilities, caching features, and Hypertext Transfer Protocol (HTTP) handlers to synchronously and asynchronously process Web service requests that are formatted using XML and SOAP.

As you can see, these layers build on one another to form a comprehensive framework. The importance of the framework is that it provides a way for applications to communicate regardless of the programming language in which they are written. Thus, .NET-enabled applications can communicate with legacy applications written in COBOL and those running on mainframes just as easily as they can communicate with applications written in Java or ASP.NET.

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