How to invoke WebService in ASP.net ajax

Ajax|asp.net|web

Today I want to implement the use of JavaScript invoke WebService I first thought of ASP.net Ajax because Microsoft's things with convenience, I looked from the Internet, this thing many people have written, I took a demo from the official look at the source code, feel nothing special, So I started to write. Add a webservice.asmx and then join ScriptManager in Default.aspx and set serviecs properties



Services>

Then I've added a button and specified the click event for it.
hello world
Next, start writing the script.

There should be no problem, but when you click on the button, the wrong foot webservice undefined
I began to compare with others, in the end what is wrong, at first I thought it was a script to write the wrong, and then see webservice that part of the discovery of others as a Microsoft.Web.Script.Services; this namespace, and before the class set the [ ScriptService] Property, I think the problem may be here, plus on it!

Http://www.cnblogs.com/interboy/archive/2006/11/26/573045.html