Consuming Web Ser vices Via Soap Messages Các chương trước đã thảo luận các lớp AJAX giao tiếp client-server và các thành phần cấu thành của nó. Bạn đã học được cách sử dụng WebRequest, WebRequestManager, và WebRequestExecutor có những yêu cầu không đồng bộ ở bên phải máy chủ từ bên trong mã clientside của bạn. Chương này được xây dựng dựa trên những gì bạn đã học trong chương trước để cho bạn thấy làm thế nào để tiêu thụ các dịch vụ Web trong các ứng dụng AJAX của bạn. Chương này bắt đầu bằng. | Consuming Web Services Via Soap Messages The previous chapter discussed the AJAX client-server communication layer and its constituent components. You learned how to use WebRequest WebRequestManager and WebRequestExecutor to make asynchronous requests to the server right from within your clientside code. This chapter builds on what you learned in the previous chapter to show you how to consume Web services in your AJAX applications. The chapter begins by implementing an Web service. It then shows you how to use the techniques that you learned in the previous chapter to consume this Web service in an AJAX application. Building the Web Service In the previous chapter a Web page was implemented that uses the WebRequest WebRequestExecutor and WebRequestManager AJAX client classes to make an asynchronous page post back to the server to retrieve detailed information about a given employee. In Listing 12-58 the Page_Load method is the server-side method responsible for validating an employee s credentials and returning the detailed employee information back to the requesting browser. This section implements a Web service that does exactly what the Page_Load method does it validates user credentials and returns the detailed employee information to the requesting browser. In other words instead of asynchronously posting back to itself to validate user credentials and retrieve the employee information the page makes an asynchronous call into this Web service. Although the end result is the same both approaches validate user credentials and retrieve the employee information the mechanisms are quite different. Whereas one uses page post back the other calls into a Web service. Listing 13-1 presents the implementation of this Web service called Employeeinfo. It exposes a single Web-callable method named GetEmployeeinfo that takes the username and password as its argument validates user credentials and returns the employee information. As
