Introduction to Ajax Technology (1)

Ajax

xml-based asynchronous JavaScript, referred to as Ajax, is a crown in the current web innovation (called Web2.0). Thanks to the various technologies that make up Ajax, Web application interactions such as Flickr, backpack and Google have made a qualitative leap in this area. The term derives from a description of the conversion from web-based Web applications to data-based applications. In a data-based application, the user needs data such as a contact list that can be obtained from a server that is independent of the actual Web page and can be dynamically written to the Web page, rendering the slow Web application experience as a desktop application.

Although most developers have used XMLHTTP in the past or used an IFRAME to load data, only now do we see traditional developers and companies starting to adopt these technologies. Like new programming languages or models with more pain, developers need to learn new tricks and how best to make use of these new technologies.

Ajax mode

Many important technologies and Ajax development patterns can be obtained from existing knowledge. For example, in an application that sends a request to a server, it must include the order of request, priority, timeout response, error handling, and callbacks, many of which have already been included in the Web service, like today's SOA. Ajax developers have a complete knowledge of the system architecture. At the same time, as the technology matures there will be many areas to improve, especially the usability of the UI component.

Ajax development differs greatly from the traditional CS development. These differences introduce new programming problems, and the biggest problem is ease of use. Because Ajax relies on browser JavaScript and XML, browser compatibility and support standards become as important as JavaScript run-time performance. Most of these problems come from a combination of browsers, servers, and technologies, so it is important to understand how best to use these technologies.

With the combination of varying technologies and a strong coupled client-server environment, AJAX presents a new development approach. Ajax developers must understand the traditional MVC architecture, which limits the boundaries between application hierarchies. At the same time, developers need to consider the outside of the CS environment and use AJAX technology to reset the MVC boundaries. Most importantly, AJAX developers must prevent the Web application from being considered as a single page in the form of a collection of pages. Once the scope between the UI design and the service architecture is strictly differentiated, the developer needs to update and change the technology collection.

Always thinking about the user

The biggest opportunity for Ajax is the user experience. The rules for defining Web applications are being rewritten in the process of making applications more responsive and innovative, so developers must focus more on users. Now the user has become accustomed to using web apps. For example, users usually want to have a few seconds of delay and screen refresh for each button click, but Ajax is breaking this long time. So the user needs to relive the button click Response.

Usability is an exciting place for Ajax and has produced several novel technologies. One of the most striking is a technology called "Yellow Stealth", which turns the user interface into yellow before the data is updated, and restores the original color immediately after the update is complete. Ajax developers freed users from the load of Web applications, carefully leveraging the rich interfaces provided by Ajax, and soon desktop developers found Ajax to be their direction.

Several tools and techniques

As Ajax quickly stands out, I think the developer's expectation of this technology is increasing rapidly. Like any new technology, the boom in Ajax needs to be supported by a whole development tool/programming language and related technology systems.

Javascript

The most important and most overlooked of the Ajax concepts shown in the name is that he is also a JavaScript programming language. JavaScript is an adhesive that integrates the parts of an AJAX application. Most of the time, JavaScript is often considered by the server-side developer as an enterprise-class application that should be avoided as much as possible. This view comes from the previous experience of writing JavaScript code: a complex and error-prone language. Similarly, he is also thought to spread the application logic arbitrarily across both the server and the client, making the problem difficult to discover and code difficult to reuse. In Ajax, JavaScript is used primarily to pass data from the user interface to the server and return results. The XMLHttpRequest object is used to respond to data passed over HTTP, and once the data is returned to the client, it is immediately possible to use the DOM to place the data on the network surface.