【正文】 式向用戶公開。例如，如果連接已超出范圍但沒有顯式關(guān)閉，則僅當(dāng)達(dá)到最大池大小而該連接仍然有效時(shí)，該連接才會(huì)返回到連接池中。 應(yīng)用程序的安全標(biāo)識(shí)可設(shè)置為幾個(gè)不同的選項(xiàng)之一。 是一個(gè)已編譯的、基于 .NET 的環(huán)境，可以用任何與 .NET 兼容的語言 （包括 Visual Basic .NET、 C 和 JScript .NET.）創(chuàng)作應(yīng)用程序。生成這些頁時(shí)，可以使用 服務(wù)器控件來創(chuàng)建公共 UI 元素，以及對(duì)它們進(jìn)行編程以用于 執(zhí)行常見的任務(wù)。這些功能以及使用它們的方法概述如下： ? 如果您具有 ASP 開發(fā)技能，則新的 編程模型對(duì)您來說將會(huì)是非常熟悉的。 ? 提供一種簡(jiǎn)單的模型，該模型使 Web 開發(fā)人員能夠編寫在應(yīng)用程序級(jí)運(yùn)行的邏輯。另外，它還可以提供相對(duì)于 ASP 和其他 Web 開發(fā)平臺(tái)來說顯著的性能改進(jìn)。 提供 TraceContext 類，在開發(fā)頁面時(shí)該類用于在頁面上編寫自定義調(diào)試語句。 ? IIS 使用一個(gè)稱為輔助進(jìn)程隔離模式的新進(jìn)程模型，它不同于 IIS 早期版本中使用的進(jìn)程模型。） 以下代碼段說明在 ViewState 中保存的屬性。如果有若干依賴通用數(shù)據(jù) 的屬性，則可以通過只將關(guān)鍵元素存留到 ViewState 來優(yōu)化性能。 Overview of the .NET Framework The .NET Framework is an integral Windows ponent that supports building and running the next generation of applications and XML Web services. The .NET Framework is designed to fulfill the following objectives: ? To provide a consistent objectoriented programming environment whether object code is stored and executed locally, executed locally but Interdistributed, or executed remotely. ? To provide a codeexecution environment that minimizes software deployment and versioning conflicts. ? To provide a codeexecution environment that promotes safe execution of code, including code created by an unknown or semitrusted third party. ? To provide a codeexecution 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 Windowsbased applications and Webbased applications. ? To build all munication on industry standards to ensure that code based on the .NET Framework can integrate with any other code. The .NET Framework has two main ponents: the mon language runtime and the .NET Framework class library. The mon 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 promote 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 ponent of the .NET Framework, is a prehensive, objectoriented collection of reusable types that you can use to develop applications ranging from traditional mandline or graphical user interface (GUI) applications to applications based on the latest innovations provided by , such as Web Forms and XML Web services. The .NET Framework can be hosted by unmanaged ponents that load the mon 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 thirdparty runtime hosts. For example, hosts the runtime to provide a scalable, serverside environment for managed code. works directly with the runtime to enable applications and XML Web services, both of which are discussed later in this topic. Inter Explorer is an example of an unmanaged application that hosts the runtime (in the form of a MIME type extension). Using Inter Explorer to host the runtime enables you to embed managed ponents or Windows Forms controls in HTML documents. Hosting the runtime in this way makes managed mobile code (similar to Microsoft174。 almost all existing ASP pages will have to be modified to some extent in order to run under . In addition, major changes to Visual Basic .NET mean that existing ASP pages written with Visual Basic Scripting Edition typically will not port directly to . In most cases, though, the necessary changes will involve only a few lines of code. ? Accessing databases from applications is an oftenused technique for displaying data to Web site visitors. makes it easier than ever to access databases for this purpose. It also allows you to manage the database from your code. ? provides a simple model that enables Web developers to write logic that runs at the application level. Developers can write this code in the text file or in a piled class deployed as an assembly. This logic can include applicationlevel events, but developers can easily extend this model to suit the needs of their Web application. ? provides easytouse application and sessionstate facilities that are familiar to ASP developers and are readily patible with all other .NET Framework APIs. ? For advanced developers who want to use APIs as powerful as the ISAPI programming interfaces that were included with previous versions of ASP, offers the IHttpHandler and IHttpModule interfaces. Implementing the IHttpHandler interface gives you a means of interacting with the lowlevel request and response services of the IIS Web server and provides functionality much like ISAPI extensions, but with a simpler programming model. Implementing the IHttpModule interface allows you to include custom events that participate in every request made to your application. ? takes advantage of performance enhancements found in the .NET Framework and mon language runtime. Additionally, it has been designed to offer significant performance improvements over ASP and other Web development platforms. All code is piled, rather than interpreted, which allows early binding, strong typing, and justintime (JIT) pilation to native code, to name only a few of its benefits. is also easily factorable,。 controls) possible, but with significant improvements that only managed code can offer, such as semitrusted execution and isolated file storage. The follow