Sau đó bạn có thể tạo ra một tên cho các tài liệu tham khảo web và thêm các tham chiếu đến dự án của bạn. Tại thời điểm này trong dự án của bạn, bạn có thể tạo ra một thể hiện của lớp web proxy tham khảo và gọi phương thức trên nó để có được dữ liệu trở lại từ các dịch vụ web. | CHAPTER 4 Data Binding with Most applications use some form of data store with the application itself being a means to store retrieve manipulate and view data. These applications might use a SQL Server 2005 database a storage area network or even a simple XML file. Web applications are no exception and typically these applications are termed data-driven applications. When it comes to retrieving and representing data a myriad of options are available over time the technology has evolved dramatically. The reason for this is that the code needed to access data and the engines that run the data itself tend to be resource heavy and in situations such as on the Web where they may be used in clustered environments . the same application running on a number of machines and serving millions of users they can be expensive to maintain. As a result the technology that developers use to create data-driven applications has evolved rapidly driven by the needs of scaling to large audiences. .NET provides a data programming technology for you to use in your applications. It is called . It consists of a number of managed classes that enable your applications to connect to data sources execute commands and manage disconnected data. In this chapter you ll look at the architecture of and how it works to bring data to your application. You ll look into the SQL Server 2005 Express edition a free version of the industryleading enterprise database software from Microsoft as well as a sample database AdventureWorks that is used to demonstrate many of its features. You ll wrap the chapter up with a tour through some of the server controls that can be used to provide data awareness to your web application through data binding. What Is Scalability is typically achieved by breaking an application into functional tiers. As I mentioned in the previous chapter keeping state between tiers has a high cost when it comes to scalability performance and security. .
