- What is ASP.NET?
- What is an ASP.NET Application?
ASP.NET
What is ASP.NET?
ASP.NET is a .NET programming framework built that on the common language runtime that can be used on a server to build powerful Web applications. ASP.NET can be consider as the front end script of a wen application. The back end script can be either VB.NET,C# or other compatible programming language. VB.NET and C# is the most common use of language in ASP.NET web application. ASP.NET offers several important advantages over previous Web development models:
Enhanced Performance.
ASP.NET is compiled common language runtime code running on the server. Unlike its interpreted predecessors, ASP.NET can take advantage of early binding, just-in-time compilation, native optimization, and caching services right out of the box. This amounts to dramatically better performance before you ever write a line of code.
World-Class Tool Support.
The ASP.NET framework is complemented by a rich toolbox and designer in the Visual Studio integrated development environment. WYSIWYG editing, drag-and-drop server controls, and automatic deployment are just a few of the features this powerful tool provides. But there is also something that programmer must be careful is the balance of server script and client script. Due to the flexibility of drag and drop feture many beginner in .NET web application will having the same problem where their web application design are over loaded the server with server script, ASP.NET.
Power and Flexibility.
Because ASP.NET is based on the common language runtime, the power and flexibility of that entire platform is available to Web application developers. The Common Language Runtime (CLR), which is the execution environment for all programs in the .NET Framework. The
CLR is similar to a Java Virtual Machine (VM) in that it interprets
byte code and executes it on the fly, while simultaneously
providing services such as garbage collection and exception
handling. Unlike a Java VM, which is limited to the Java language,
the CLR is accessible from any compiler that produces
Microsoft Intermediate Language (IL) code, which is similar to
Java byte code. Code that executes inside the CLR is referred to
as managed code. Code that executes outside its boundaries is
called unmanaged code. The .NET Framework class library, Messaging, and Data Access solutions are all seamlessly accessible from the Web. ASP.NET is also language-independent, so you can choose the language that best applies to your application or partition your application across many languages. Further, common language runtime interoperability guarantees that your existing investment in COM-based development is preserved when migrating to ASP.NET.
Simplicity.
ASP.NET makes it easy to perform common tasks, from simple form submission and client authentication to deployment and site configuration. For example, the ASP.NET page framework allows you to build user interfaces that cleanly separate application logic from presentation code and to handle events in a simple, Visual Basic - like forms processing model. Additionally, the common language runtime simplifies development, with managed code services such as automatic reference counting and garbage collection.
Manageability.
ASP.NET employs a text-based, hierarchical configuration system, which simplifies applying settings to your server environment and Web applications. Because configuration information is stored as plain text, new settings may be applied without the aid of local administration tools. This "zero local administration" philosophy extends to deploying ASP.NET Framework applications as well. An ASP.NET Framework application is deployed to a server simply by copying the necessary files to the server. No server restart is required, even to deploy or replace running compiled code.
Scalability and Availability.
ASP.NET has been designed with scalability in mind, with features specifically tailored to improve performance in clustered and multiprocessor environments. Further, processes are closely monitored and managed by the ASP.NET runtime, so that if one misbehaves (leaks, deadlocks), a new process can be created in its place, which helps keep your application constantly available to handle requests.
Customizability and Extensibility.
ASP.NET delivers a well-factored architecture that allows developers to "plug-in" their code at the appropriate level. In fact, it is possible to extend or replace any subcomponent of the ASP.NET runtime with your own custom-written component. Implementing custom authentication or state services has never been easier.
Security.
With built in Windows authentication and per-application configuration, you can be assured that your applications are secure.
What is an ASP.NET Application?
ASP.NET defines an application as the sum of all files, pages, handlers, modules, and executable code that can be invoked or run in the scope of a given virtual directory (and its subdirectories) on a Web application server. For example, an "order" application might be published in the "/order" virtual directory on a Web server computer. For IIS the virtual directory can be set up in the Internet Services Manager; it contains all subdirectories, unless the subdirectories are virtual directories themselves.
Each ASP.NET Framework application on a Web server is executed within a unique .NET Framework application domain, which guarantees class isolation (no versioning or naming conflicts), security sandboxing (preventing access to certain machine or network resources), and static variable isolation.
ASP.NET maintains a pool of HttpApplication instances over the course of a Web application's lifetime. ASP.NET automatically assigns one of these instances to process each incoming HTTP request that is received by the application. The particular HttpApplication instance assigned is responsible for managing the entire lifetime of the request and is reused only after the request has been completed. This means that user code within the HttpApplication does not need to be reentrant.
Creating an Application
To create an ASP.NET Framework application you can use an existing virtual directory or create a new one. For example, if you installed Windows 2000 Server including IIS, you probably have a directory C:\InetPub\WWWRoot. You can configure IIS using the Internet Services Manager, available under Start -> Programs -> Administrative Tools. Right-click on an existing directory and choose either New (to create a new virtual directory) or Properties (to promote an existing regular directory).
Lifetime of an Application
An ASP.NET Framework application is created the first time a request is made to the server; before that, no ASP.NET code executes. When the first request is made, a pool of HttpApplication instances is created and the Application_Start event is raised. The HttpApplication instances process this and subsequent requests, until the last instance exits and the Application_End event is raised.
Note that the Init and Dispose methods of HttpApplication are called per instance and thus can be called several times between Application_Start and Application_End. Only these events are shared among all instances of HttpApplication in one ASP.NET application.
Top
Real Estate Information
![[Company Logo Image]](images/logo.gif){kind=logo}
