Ajax Basics Tutorial (2)-Using the XMLHttpRequest object 2.7 DOM level 3 to load and save the Protocol

So far, the solutions we've discussed are not standards. Although XMLHttpRequest is widely supported, you've seen that the process of creating XMLHttpRequest objects differs depending on the browser. Many people mistakenly believe that Ajax is supported by the consortium, but not in practice. The consortium solves this and other drawbacks in a new standard whose name is fairly long: DOM Level 3 Loads and saves the specification. The purpose of this specification is to modify the contents of the DOM document with XML content in a platform-and language-independent manner. The 1.0 version was presented in April 2004, but so far no browsers have implemented the protocol.

When will loading and saving the protocol replace Ajax? No one knows. Think about how many browsers don't fully support existing standards, so it's hard to say, but as more and more sites and apps take advantage of Ajax technology, it's possible that future versions will be supported. However, earlier versions of the DOM took a long time to get adoption, so you have to be patient. In an interview, DOM activity chairman Philippe Le Hégaret said it would take "quite a long time" to be widely adopted. DOM Level 3 also has some support, opera's XMLHttpRequest implementation is based on DOM level 3, and the Java XML processing API (Java API for XML PROCESSING,JAXP) version 1.3 also supports DOM Level 3. However, from the point of view of the corresponding rules of the consortium, at least the importance of Ajax technology can be demonstrated.

Since August 1997, people have been trying to solve the incompatibility between browsers, and the loading and saving of the protocol has reached the extreme. You may notice that the title says "Level 3", then level 1 and Level 2? Level 1 was completed in October 1998, bringing US HTML 4.0 and XML 1.0. Today, Level 1 has been widely supported. November 2000, Level 2 completed, but it was adopted relatively slowly. CSS is part of Level 2.

What can developers get from loading and saving the protocol? Ideally, it will solve many of the cross-browser problems we currently encounter. Although Ajax is simple, you should remember that just to create an instance of the XMLHttpRequest object, you need to check the type of browser. A real business-like protocol can reduce this code-writing effort. Basically, loading and saving the specification provides a common API for Web developers to access and modify the DOM in a platform-and language-independent way. In other words, whether your platform is Windows or Linux, it doesn't matter whether you're developing it in VBScript or using JavaScript. You can also save a DOM tree as an XML document, or load an XML document into the DOM. In addition, the Statute provides support for XML 1.1, XML Schema 1.0, and SOAP 1.2. This protocol is likely to be widely used by developers.

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