The
.NET Framework is a new computing platform that simplifies application
development in the highly distributed environment of the Internet. The .NET
Framework is designed to fulfill the following objectives:
·
To provide a consistent object-oriented
programming environment whether object code is stored and executed locally,
executed locally but Internet-distributed, or executed remotely.
·
To provide a code-execution environment
that minimizes software deployment and versioning conflicts.
·
To provide a code-execution environment
that guarantees safe execution of code, including code created by an unknown or
semi-trusted third party.
·
To provide a code-execution environment
that eliminates the performance problems of scripted or interpreted
environments.
·
To make the developer experience consistent
across widely varying types of applications, such as Windows-based applications
and Web-based applications.
·
To build all communication on industry
standards to ensure that code based on the .NET Framework can integrate with
any other code.
The
.NET Framework has two main components: the common language runtime and the
.NET Framework class library. The common language runtime is the foundation of
the .NET Framework. You can think of the runtime as an agent that manages code
at execution time, providing core services such as memory management, thread
management, and Remoting, while also enforcing strict type safety and other
forms of code accuracy that ensure security and robustness. In fact, the
concept of code management is a fundamental principle of the runtime. Code that
targets the runtime is known as managed code, while code that does not target
the runtime is known as unmanaged code. The class library, the other main component
of the .NET Framework, is a comprehensive, object-oriented collection of
reusable types that you can use to develop applications ranging from
traditional command-line or graphical user interface (GUI) applications to
applications based on the latest innovations provided by ASP.NET, such as Web
Forms and XML Web services.
The
.NET Framework can be hosted by unmanaged components that load the common
language runtime into their processes and initiate the execution of managed
code, thereby creating a software environment that can exploit both managed and
unmanaged features. The .NET Framework not only provides several runtime hosts,
but also supports the development of third-party runtime hosts.
For example, ASP.NET hosts the runtime to provide a
scalable, server-side environment for managed code. ASP.NET works directly with
the runtime to enable Web Forms applications and XML Web services, both of
which are discussed later in this topic.
Internet Explorer is an example of an unmanaged
application that hosts the runtime (in the form of a MIME type extension).
Using Internet Explorer to host the runtime enables you to embed managed
components or Windows Forms controls in HTML documents. Hosting the runtime in
this way makes managed mobile code (similar to Microsoft® ActiveX® controls)
possible, but with significant improvements that only managed code can offer,
such as semi-trusted execution and secure isolated file storage.
The following illustration shows the relationship of
the common language runtime and the class library to your applications and to
the overall system. The illustration also shows how managed code operates
within a larger architecture.
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