Introduction to Ajax Technology (2)

Ajax XMLHttpRequest

The XMLHttpRequest object is implemented on most browsers and has a simple interface that allows data to be delivered from the client to the server, but does not interrupt the user's current operation. Data transmitted using XMLHttpRequest can be in any format, although it is suggested from the first name as XML-formatted data.

Developers should already be familiar with many other XML-related technologies. XPath can access data in an XML document, but it is necessary to understand the XML DOM. Similarly, XSLT is the simplest and fastest way to generate HTML or XML from XML data. Many developers are already familiar with XPath and XSLT, so it makes sense for Ajax to choose XML as a data interchange format. XSLT can be used on both the client and server side, and he can reduce the number of application logic written in JavaScript.

Css

CSS is an important weapon that Ajax developers need to navigate to the right AJAX application. CSS provides a mechanism for separating application styles and designs from content. Although CSS plays a crucial role in AJAX applications, it is also a major impediment to building a Cross-browser application because different browser vendors support a variety of CSS levels.

Server-side

But unlike on the client side, AJAX applications at the server end are used or built in like Java. NET and PHP language based mechanisms; there is no change in the main way in this field.

That being the case, our interest in the Ruby on Rails framework has increased rapidly. More than a year ago, Ruby on Rails had attracted a large number of developers to build web and Ajax applications based on their powerful capabilities. While there are many quick application development tools available, Ruby on rails seems to have the ability to simplify building AJAX applications.

Development tools

In the actual building of AJAX applications, you need more than just a text editor. Since JavaScript is not compiled, he can easily write and run in the browser, however, many tools offer useful extensions such as syntax highlighting and intelligent completion.

Different ides provide different levels of support for JavaScript. IntelliJ idea from JetBrains is a better IDE for JavaScript development, although many developers also like Microsoft's Visual Studio products (promising to improve AJAX support in the latest release). Eclipse contains two free JavaScript editor plug-ins and a commercially available Komodo IDE from Activestat.

Another problem with JavaScript and Ajax development is the difficulty of debugging. Different browsers provide different Run-time error messages that are usually hidden, and JavaScript bugs such as double variable assignment (usually due to lack of data types) make debugging more difficult. In the development of Ajax, debugging is more complicated, because it needs to identify whether the client or server-side error. In the past, the way JavaScript was debugged was to delete all the code and then increase the line until the error occurred. Now, more developers are back to Microsoft Script Debugger for IE and the Venkman for Mozilla browsers.

Browser compatibility

The biggest problem with JavaScript programming comes from the support of different browsers for various technologies and standards. Building a run in different browsers (IE and Firefox) is a difficult task. So several Ajax JavaScript frameworks either generate JavaScript based on server-side logic or tag libraries, or provide a client JavaScript library that conforms to cross-browser Ajax development. Some popular frameworks include: Ajax.NET, Backbase, Bitkraft, Django, DOJO, DWR, MochiKit, Prototype, Rico,
Sajax, Sarissa, and Script.aculo.us.

These frameworks give developers more room than they need to worry about cross-browser issues. While these frameworks enhance the developer's ability to build applications, there are a number of other factors to consider in the Ajax component market as vendors have developed a more detailed user interface packaged component solution. For example, several vendors that provide common user interface components such as combo boxes and data grids can be used to create a good experience in the application to view and edit data in a spreadsheet-like format. These components, however, not only encapsulate the user interface of the component, but also communicate with the server-side data, which typically uses a tagging approach to implement such as ASP.net or JSF controls.

Prospect

The recent browser rivalry between IE and Firefox has become hot, so Ajax developers need to be quick enough to respond. Key points are in some issues such as CSS or XML, although various browsers form different camps with the latest standards (such as Mozilla embracing SVG and e4x standards and using XUL in the latest Firefox beta version, while Microsoft uses its own XAML technology). All of these technologies represent a change in the market direction of current Ajax mainstream JavaScript and XML.

In general, Ajax developers must follow up on the latest technology and take advantage of the high productivity toolset as quickly as possible. Successful AJAX developers also need to keep an eye on their users to avoid magnifying any problems. and Ajax developers need to innovate continuously to create new ways to enhance usability of Web applications.