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http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dtssql/dts_usage_3ayb.asp
Introduction to ASP.NET
Introduction to the environment of ASP.NET
ASP.NET is more than the next version of Active Server Pages(ASP).It is a unified Web development platform that provides the services necessary for developers to build enterprise-class Web applications. While ASP.NET is largely syntax compatible with ASP, it also provides a new programming model and infrastructure for more secure, scalable, applications. You can feel free to augment your ASP applications by incrementally adding ASP.NET functionality to them.
ASP.NET is a compiled, .NET-based environment; you can author application in any .NET compatible language, including Visual Basic .NET, C#, and JScript .NET. Additionally, the entire .NET Framework is available to any ASP.NET application.Developers can easily access the benefits of these technologies, which include the managed common language runtime environment, type safety, inheritance, and so on.
ASP.NET has been designed to work seamlessly with WYSIWYG HTML editors and other programming tools, including Microsoft Visual Studio .NET. Not only does this make Web development easier, but it also provides all the benefits that these tools have to offer, including a GUI that developers can use to drop server controls onto a Web page and fully integrated debugging support.
The functions of ASP.NET
(1)If you have ASP development skills, the new ASP.NET programming model will seem very familiar to you. However, ASP.NET object has changed significantly from ASP, making it more structured and object-oriented. Unfortunately this means that ASP.NET is not fully backward compatible; all existing ASP pages will have to be modified to run under ASP.NET. In addition, major changes to Visual Basic .NET mean that ASP pages written with Visual Basic Edition typically will not directly to ASP.NET. In most cases, though, the necessary changes will involve only a few lines of code.
(2)Accessing databases from ASP.NET applications is an often-used technique for displaying data to Web site visitors. ASP.NET makes it easier than ever to access databases for this purpose. It also allows you to manage the database from your code.
(3)ASP.NET provides a simple model that enables Web developers to write logic that runs at application level. Developers can write code in Global.asax file deployed as an assembly. This logic include application-level events, but developers can easily extend this model to suit the needs of Web application.
(4)ASP.NET provides easy-to-use application and session-state facilities that are familiar to ASP developers and are readily compatible with all other .NET Framework APIs.
(5)For advanced developers who want to use APIs as powerful as the ISAPI programming interfaces that were included with previous versions of ASP, ASP.NET offers the IHttpHandler and IHttpModule interfaces. Implementing the IHttpHandler interface gives a means of interacting with the low-level 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.
(6)ASP.NET takes advantage of performance enhancements found in the .NET Framework and common language runtime. Additionally, it has been designed to offer significant performance improvements over ASP an. All ASP.NET code is compiled, rather than interpreted, which allows early binding, strong typing, and just-in-time (JIT) compilation to native code, to name only a few of its benefits. ASP.NET is also easily factorable, meaning that developers can remove modules (a session module, for instance) that are not relevant to the application.ASP.NET provides extensive caching services.ASP.NET also ships with performance counters that developers and system administrators can monitor to test new applications and gather metrics on existing applications.
(7)Writing custom debug statements to your Web page can help immensely in troubleshooting your application's code. However, they can cause embarrassment if they are not removed. The problem is that removing the debug statements from your pages when your application is ready to be ported to a production server can require significant effort. ASP.NET offers the TraceContext class, which allows you to write custom debug statements to your pages as you develop them. They appear only when you have enabled tracing for a page or entire application. Enabling tracing appends details about a request to the page, or, if you so specify, to a custom trace viewer that is stored in the root directory of your application.
(8)The .NET Framework and ASP.NET provide default authorization for Web applications. You can easily remove, add to, replace these schemes, depending upon the needs of your application.
(9)ASP.NET configuration are stored in XML-based files, which are human readable and writable. Each of your applications can have a distinct configuration file,you can extend the configuration scheme to suit your requirements. For more information, see ASP.NET Configuration.
(10)Applications are said to be running side by side when they are installed on the same computer but use different versions of the .NET Framework.
(11)IIS 6.0 uses a new process model called worker process isolation mode, which is different from the process model used in previous versions of IIS. ASP.NET uses this model by default when running on Windows Server 2003.
Building solutions with .NET technologies, you can create and connect to an infinite variety of personalized .NET experiences, with industry-standard technologies helping to protect your security and safety. Individuals can enjoy rich, tailored interactions—.NET experiences—when Web services are pulled together, allowing access to information across the Internet and from stand-alone applications, online or offline.
Most consumers will never notice that the .NET Framework is running on their Pocket PC, smartphone, or desktop computer. But they may appreciate the reliability, ease of use, and ability to connect to other systems that the .NET Framework helps bring to computers. The .NET Framework helps software developers and systems administrators more easily build and maintain systems with improvements toward performance, security, and reliability.
The Microsoft .NET Framework is an important new component of the Microsoft Windows® family of operating systems. It is the foundation of the next generation of Windows-based applications that are easier to build, deploy, and integrate with other networked systems. The .NET Framework simplifies Windows software development. It provides developers with a single approach to build both desktop applications—sometimes called smart client applications—and Web-based applications. It also enables developers to use the same tools and skills to develop software for a variety of systems ranging from handheld smartphones to large server installations.Software built on the .NET Framework can be easier to deploy and maintain than conventional software. Applications can be designed to automatically upgrade themselves to the latest version. The .NET Framework can also minimize conflicts between applications by helping incompatible software components coexist.
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.
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 introduction to ADO.NET
ADO.NET is designed specifically for message-based Web applications while still providing preferable functionality for other application architectures. By supporting loosely coupled access to data, ADO.NET maximizes data sharing by reducing the number of active connections to the database — reducing the possibility of multiple users contending for limited resources on the database server.
ADO.NET provides several ways to access data. If your Web application or XML Web service requires data access from multiple sources, needs to interoperate with other applications (both local and remote), or can benefit from persisting and transmitting cached results, the dataset is an excellent choice. As an alternative, ADO.NET provides data commands and data readers to communicate directly with the data source. Direct database operations using data commands and data readers include running queries and stored procedures, creating database objects, and performing direct updates and deletes using DDL commands.
ADO.NET maximizes data sharing by supporting an XML-based persistence and transmission format for the fundamental object of distributed ADO.NET applications: the dataset. A dataset is a relational data structure that can be read from, written to, or serialized using XML. ADO.NET datasets make it easy to build applications that require loosely coupled data interchange between application tiers and multiple Web sites.
Because datasets are remoted as XML, any two components can share data and use XML schemas to define the relational structure of the dataset. And, because the dataset's serialization format is XML, DataSet objects can easily pass through firewalls without restrictions. In addition to loading data from XML, datasets can be populated with, and hold changes to, data from SQL Server as well as data sources exposed via OLE DB.
英文翻译
1 ASP.NET环境简介
ASP.NET 不仅仅是下一版本的 Active Server Page (ASP)；它是统一的 Web 开发平台，用来提供开发人员生成企业级 Web 应用程序所需的服务。ASP.NET 的语法在很大程度上与 ASP 兼容，同时它还提供一种新的编程模型和结构，用于生成更安全、可伸缩和稳定的应用程序。可以通过在现有 ASP 应用程序中逐
渐添加 ASP.NET 功能，随时增强该 ASP 应用程序的功能。
ASP.NET 是一个已编译的、基于 .NET 的环境，可以用任何与 .NET 兼容的语言（包括 Visual Basic .NET、C# 和 JScript .NET.）创作应用程序。另外，任何 ASP.NET 应用程序都可以使用整个 .NET Framework。开发人员可以方便地获得这些技术的优点，其中包括托管的公共语言运行库环境、类型安全、继承等等。
ASP.NET 可以无缝地与 WYSIWYG HTML 编辑器和其他编程工具（包括 Microsoft Visual Studio .NET）一起工作。这不仅使得 Web 开发更加方便，而且还能提供这些工具必须提供的所有优点，包括开发人员可以用来将服务器控件拖放到 Web 页的 GUI 和完全集成的调试支持。
2 ASP.NET 的功能
(1)如果具有 ASP 开发技能，则对新的 ASP.NET 编程模型将会是非常熟悉的。不过，与 ASP 相比，ASP.NET 对象模型变化显著，它更为结构化并且面向对象。但这也意味着 ASP.NET 不是完全向后兼容的；几乎所有现有的 ASP 页都必须经过一定程度的修改后才可以在 ASP.NET 下运行。此外，对 Visual Basic .NET 的一些主要更改也意味着，用 Visual Basic Scripting 版本编写的现有 ASP 页通常将不会直接移植到 ASP.NET 中。不过，在大多数情况下，只需对少数几行代码进行必要的修改。
(2)从 ASP.NET 应用程序访问数据库是向 Web 站点访问者显示数据的常用技术。ASP.NET 使得为此目的而对数据库的访问比以往更加方便。它还使您能够从您的代码管理数据库。
(3)ASP.NET 提供一种简单的模型，该模型使 Web 开发人员能够编写在应用程序级运行的逻辑。开发人员可以在 Global.asax 文本文件中或在作为程序集部署的已编译类中编写这种代码。这种逻辑可以包括应用程序级事件，但开发人员可以轻松地扩展这种模型，以适应他们的 Web 应用程序的需要。
(4)ASP.NET 提供易用的应用程序和会话状态功能，它们对于 ASP 开发人员来说是熟悉的，且容易与所有其他 .NET Framework API 兼容。
(5)对于需要使用像 ISAPI 编程接口（随附于以前的 ASP 版本中）那样功能强大的 API 的高级开发人员，ASP.NET 提供了IHttpHandler 和 IHttpModule 接口。实现IHttpHandler接口，给您提供了一种与 IIS Web 服务器的低级别请求和响应服务交互的手段，并提供与 ISAPI 扩展非常类似的功能，但编程模型却较为简单。实现 IHttpModule接口使您可以包含参与对应用程序发出的每个请求的自定义事件。
(6)ASP.NET 利用 .NET Framework和公共语言运行库中的性能增强功能。另外，它还可以提供相对于ASP和其他Web开发平台来说显著的性能改进。所有 ASP.NET 代码都是编译的，而不是解释的，这就允许对本机代码采用早期绑定，强类型处理，以及实时(JIT)编译，这里只列举几个优点而已。ASP.NET还可方便地分解，即开发人员可以移除那些与他们开发的应用程序不相关的模块（例如，会话模块）。ASP.NET还提供丰富的缓存服务（包括内置服务和缓存 API 两种）。ASP.NET还提供性能计数器，开发人员和系统管理员可以监视这些性能计数器，以测试新的应用程序和搜集有关现有应用程序的度量标准。
(7)在Web页中编写自定义调试语句，对排除应用程序代码中的错误非常有帮助。但是，如果不移除它们，则会带来麻烦。问题是，在应用程序准备好移植到生产服务器时从页面中移除调试语句，会需要很大的工作量。ASP.NET 提供 TraceContext类，在开发页面时该类用于在页面上编写自定义调试语句。只有当您已经对页面或整个应用程序启用跟踪时它们才出现。启用跟踪还将有关请求的细节追加到页面，或者，追加到存储在应用程序根目录中的自定义跟踪查看器（如果这样指定的话）。
(8).NET Framework和ASP.NET为Web应用程序提供默认授权和验证方案。可以方便地移除、添加或者替换这些方案，这取决于应用程序的需要。
(9)ASP.NET 配置设置存储在基于 XML 的文件中，这些文件都是人可读和可写的。每一个应用程序都可以有不同的配置文件，可以扩展配置方案，以适应您的要求。
(10)当应用程序安装在同一台计算机上，但使用不同的 .NET Framework 版本时，就说应用程序是并行运行的。
(11)IIS 6.0 使用一个称为辅助进程隔离模式的新进程模型，它不同于 IIS 早期版本中使用的进程模型。当在 Windows Server 2003 上运行时，默认情况下 ASP.NET 使用该进程模型。
使用.NET技术构建解决方案，你可以创建和连接一个无限变化的个性化的.NET体验.用工业标准的技术有助于保护你的隐私和安全.可以充分享受.NET带来的无尽的个性和精心特制的交互.一旦.NET XML Web 服务被集成时，就可以用一个独立的应用程序通过互联网在线或离线地获取信息.
大多数消费者可能永远不会注意到.NET框架运行在他们的Pocket PC(掌上电脑PDA)，智能电话，或是桌面机之上.尽管如此，消费者却自始至终地可以享受到.NET框架在幕后带来的可靠性，易用性，互联性。开发者，系统管理员可在.NET框架下更容易地创建和维护系统，以获得更好的性能，更高的安全，更强的可靠。
.NET框架是微软Windows系列操作系统的一个新的重要的组件.它是下一代Windows应用程序的根基，非常容易开发和布署，整合至其他的网络系统。.NET框架简化了Windows平台的软件开发,为开发者提供了创建桌面应用程序(有时称为智能客户应用程序)和基于Web的应用程序的一条捷径,允许开发者利用相同的工具，经验开发从手持智能电话到大型服务器的各种不同系统的应用软件.基于.NET框架的应用程序比传统的应用程序更易于布署，维护.应用程序可被设计成可自动更新到其最新版本。.NET框架也能最小化共存的不兼容的组件间的冲突.
.NET Framework 是一种新的计算平台，它简化了在高度分布式 Internet 环境中的应用程序开发。.NET Framework 旨在实现下列目标：
提供一个一致的面向对象的编程环境，而无论对象代码是在本地存储和执行，还是在本地执行但在 Internet 上分布，或者是在远程执行的。
提供一个将软件部署和版本控制冲突最小化的代码执行环境。
提供一个保证代码（包括由未知的或不完全受信任的第三方创建的代码）安全执行的代码执行环境。
提供一个可消除脚本环境或解释环境的性能问题的代码执行环境。使开发人员的经验在面对类型大不相同的应用程序（如基于 Windows 的应用程序和基于 Web 的应用程序）时保持一致。按照工业标准生成所有通信，以确保基于 .NET Framework 的代码可与任何其他代码集成。
.NET Framework 具有两个主要组件：公共语言运行库和 .NET Framework 类库。公共语言运行库是 .NET Framework 的基础。您可以将运行库看作一个在执行时管理代码的代理，它提供核心服务(如内存管理、线程管理和远程处理)，而且还强制实施严格的类型安全以及可确保安全性和可靠性的其他形式的代码准确性。事实上，代码管理的概念是运行库的基本原则。以运行库为目标的代码称为托管代码，而不以运行库为目标的代码称为非托管代码。.NET Framework 的另一个主要组件是类库，它是一个综合性的面向对象的可重用类型集合，您可以使用它开发多种应用程序，这些应用程序包括传统的命令行或图形用户界面 (GUI) 应用程序，也包括基于 ASP.NET 所提供的最新创新的应用程序(如 Web 窗体和 XML Web services)。
3 ADO.NET的介绍
ADO.NET 是专为基于消息的 Web 应用程序而设计的，同时还能为其他应用程序结构提供较好的功能。通过支持对数据的松耦合访问，ADO.NET 减少了与数据库的活动连接数目（即减少了多个用户争用数据库服务器上的有限资源的可能性），从而实现了最大程度的数据共享。
ADO.NET 提供几种数据访问方法。在有些情况下，Web 应用程序或 XML Web services 需要访问多个源中的数据，或者需要与其他应用程序（包括本地和远程应用程序）进行互操作，或者可受益于保持和传输缓存结果，这时使用数据集将是一个明智的选择。作为一种替换方法，ADO.NET 提供数据命令和数据读取器以便与数据源直接通信。使用数据命令和数据读取器直接进行的数据库操作包括：运行查询和存储过程、创建数据库对象、使用 DDL 命令直接更新和删除。
ADO.NET 还通过对分布式 ADO.NET 应用程序的基本对象“数据集”(Dataset)支持基于 XML 的持久性和传输格式，来实现最大程度的数据共享。数据集是一种关系数据结构，可使用 XML 进行读取、写入或序列化。ADO.NET 数据集使得生成要求应用程序层与多个 Web 站点之间进行松耦合数据交换的应用程序变得很方便。
因为数据集被远程处理为 XML 形式，所以任何两个组件都可共享数据并使用 XML 架构来定义数据集的关系结构。而且，因为数据集的序列化格式是 XML，所以 DataSet 对象可轻松穿过防火墙，而不受任何限制。除了从 XML 加载数据以外，数据集还可用 SQL Server 中的数据以及通过 OLE DB 公开的数据源中的数据来填充，并可保存对这些数据的更改。
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