Ajax Interview Questions

Where do you find AJAX used heavily in the internet and who is investin in AJAX ?

Google is making a huge investment in developing the Ajax approach. All of the major products Google has introduced over the last year — Orkut, Gmail, the latest beta version of Google Groups, Google Suggest, and Google Maps — are Ajax applications. (For more on the technical nuts and bolts of these Ajax implementations, check out these excellent analyses of Gmail, Google Suggest, and Google Maps.) Others are following suit: many of the features that people love in Flickr depend on Ajax, and Amazon’s A9.com search engine applies similar techniques.These projects demonstrate that Ajax is not only technically sound, but also practical for real-world applications. This isn’t another technology that only works in a laboratory. And Ajax applications can be any size, from the very simple, single-function Google Suggest to the very complex and sophisticated Google Maps.And because there are so many developers out there who already know how to use these technologies, we expect to see many more organizations following Google’s lead in reaping the competitive advantage Ajax provides.

Why does HTML_AJAX hang on some server installs?

If you run into an HTML_AJAX problem only on some servers, chances are your running into a problem with output compression. If the output compression is handled in the PHP config we detect that and do the right thing, but if its done from an apache extension we have no way of knowing its going to compress the body. Some times setting HTML_AJAX::sendContentLength to false fixes the problem, but in other cases you will need to disabled the extension for the AJAX pages.We have also seen problems caused by debugging extensions like XDebug, disabling the extension on the server page usually fixes that. Problems dealing with Using HTML_AJAX, and general JavaScript development

Will HTML_AJAX integrate with other Javascript AJAX libraries such as scriptaculous?

HTML_AJAX doesn't have specific plans to integrate with other JavaScript libraries. Part of this is because external dependencies make for a more complicated installation process. It might make sense to offer some optional dependencies on a library like scriptaculous automatically using its visual effects for the loading box or something, but there is not a lot to gain from making default visuals like that flashier since they are designed to be easily replaceable.

What are the advantages of Ajax ?

The related pages on a website consist of much content that is common between them. Using traditional methods, that content would have to be reloaded on every request. However, using Ajax, a web application can request only the content that needs to be updated, thus drastically reducing bandwidth usage and load time. The use of asynchronous requests allows the client’s Web browser UI to be more interactive and to respond quickly to inputs, and sections of pages can also be reloaded individually. Users may perceive the application to be faster or more responsive, even if the application has not changed on the server side. The use of Ajax can reduce connections to the server, since scripts and style sheets only have to be requested once.

Will my server-side framework provide me with AJAX?

Most of the existing Java based frameworks already have some level of AJAX interactions and new frameworks and component libraries are being developed to provide better AJAX support. There are a lot and you can find a good list at www.ajaxpatterns.org/Java_Ajax_Frameworks. If you have not chosen a framework yet it is recommended you consider using JavaServer Faces or a JavaServer Faces based framework. JavaServer Faces components can be created and used to abstract many of the details of generating JavaScript, AJAX interactions, and DHTML processing and thus enable simple AJAX used by JSF application developer and as plug-ins in JSF compatible IDEs, such as Sun Java Studio Creator.