An architecture for distributed applications on the Internet: Overview of the Microsoft.Net Framework

Journal of SMET Education : Innovations and Research, Jan-Jun 2003 by Barnett, Bryan, Kirtland, Mary, Ganapathy, Mythreyee

Win Forms also takes advantage of the .NET Framework runtime to provide full security and ease of deployment. The framework security model can safely execute applications and components on client machines provided they are written using the Win Forms model or used from a Win Forms application. At the same time, applications can be configured to use the versions of shared components they were built and tested with, rather than using whatever component versions happen to be installed on the client machine, improving application reliability and eliminating one of the major causes of application support calls: incompatible versions of user interface controls and other shared components.

Web Applications

Web applications built on the NET Framework share the WinForms programming model, again based on the popular forms-oriented visual programming style of Visual Basic.. But here there is a distinct application model, called ASP.NET, in which a Web application is seen as just a set of URLs rooted at some base URL. Thus it encompasses both Web applications that generate pages for display in a browser and XML Web services. Like WinForms, ASP.NET takes advantage of the common language runtime and services framework to provide a reliable, robust, scalable hosting environment for Web applications. ASP.NET also benefits from the common language runtime assembly model to simplify application deployment. In addition, it provides services to simplify application development with support for things like state-management.

At the core of ASP.NET is the HTTP runtime, a high-performance runtime for processing HTTP requests that is responsible for processing all incoming HTTP requests, resolving the URL of each request to an application, and then dispatching the request to the application for further processing. The HTTP runtime is multithreaded and processes requests asynchronously, so it cannot be blocked by bad application code from processing new requests. Furthermore, the HTTP runtime assumes that failures will occur, so it is engineered to automatically recover as best it can from access violations, memory leaks, deadlocks, and so on. Barring hardware failure, the runtime aims for 100 percent availability.

ASP.NET uses the.NET Framework deployment model based on assemblies, thus gaining all its benefits such as XCOPY deployment, side-by-side deployment of assemblies, and XML-based configuration. ASP.NET also supports live updating of applications. An administrator doesn't need to shut down the Web server or even the application to update application files. Application files are never locked, so they can be overwritten even when the application is running. When files are updated, the system gracefully switches over to the new version. The system detects file changes, launches a new instance of the application using the new application code, and begins routing incoming requests to that application. When all outstanding requests being processed by the existing application instance have been handled, that instance is shut down.