AJAX Interview FAQ

Sabari · #1 (**permalink**) 11-22-2007, 10:11 PM

Question:
Should I use an HTTP GET or POST for my AJAX calls?

Answer:
AJAX requests should use an HTTP GET request when retrieving data where the data will not change for a given request URL. An HTTP POST should be used when state is updated on the server. This is in line with HTTP idem potency recommendations and is highly recommended for a consistent web application architecture.

Sabari · #2 (**permalink**) 11-22-2007, 10:12 PM

Question:
Does AJAX work with Java?

Answer:
Yes... Java is a great fit for AJAX! You can use Java Enterprise Edition servers to generate AJAX client pages and to serve incoming AJAX requests, manage server side state for AJAX clients, and connect AJAX clients to your enterprise resources. The JavaServer Faces component model is a great fit for defining and using AJAX components.

Sabari · #3 (**permalink**) 11-22-2007, 10:13 PM

Question:
What API function provides the connection between the client and server?

Answer:

XMLHttpRequest

Sabari · #4 (**permalink**) 11-22-2007, 10:13 PM

Question:
what is ajax? when ajax was born?

Answer:
"AJAX is an acronym for Asynchronous JavaScript and XML. If you think it doesn't say much, we agree. Simply put, AJAX can be read "empowered JavaScript", because it essentially offers a technique for client-side JavaScript to make background server calls(such as from PHP,ASP.NET,JSP,RUby etc) and retrieve additional data as needed, updating certain portions of the page without causing full page reloads".

The XMLHttpRequest object enables JavaScript to access the server asynchronously, so that the user can continue working, while functionality is performed in the background.

The name AJAX was born in 2005, in Jesse James Garret's article at adaptive path » essay archives 000385.php,
and gained much popularity when used by Google in many of its applications

Sabari · #5 (**permalink**) 11-22-2007, 10:15 PM

Question:

Is the server or the client in control in AJAX?

Answer:
It depends. With AJAX the answer is more in between. Control can be more centralized in a server-side component or as a mix of client-side and server-side controllers.

Centralized server-side controller - When having a more centralized controller the key is to make sure the data in client-side page is in sync with that of the server. Some applications may keep all the state on the server and push all updates to client DOM via a simple JavaScript controller.
Client and server-side controllers - This architecture would use JavaScript to do all presentation related control, event processing, page manipulation, and rendering of model data on the client. The server-side would be responsible for things such as business logic and pushing updated model data to the client. In this case the server would not have intimate knowledge of the presentation short of the initial page that would be sent to the client page request.

There are some use cases where an entire AJAX application can be written in a single page. Keep in mind if you choose this type of architecture that navigation and bookmarking should be considered.

Sabari · #6 (**permalink**) 11-22-2007, 10:17 PM

Question:
What is the role of Ajax in enhancing user experience?

Answer:
AJAX is not a new technology but a combination of several existing technologies in a new way. These include HTML, CSS, DOM, XML, XSLT, XMLHttpRequest and Javascript. The acronym AJAX stands for Asynchronous Javascript and XML. AJAX is based on open standards supported by many browsers and platforms. AJAX is a new paradigm for building web application.

Sabari · #7 (**permalink**) 11-22-2007, 10:18 PM

Q:
How can I call a Java method from Javascript?

A:
Direct Web Remoting is an open source Java library which allows for easy integration of AJAX into your web site. It allows you to call Java methods directly from Javascript.

Sabari · #8 (**permalink**) 11-22-2007, 10:19 PM

Q:
Which browsers support AJAX?

A:
Internet Explorer 5.0 and up, Opera 7.6 and up, Netscape 7.1 and up, Firefox 1.0 and up, Safari 1.2 and up, among others.

Sabari · #9 (**permalink**) 11-22-2007, 10:20 PM

Q:
Is there any way that an AJAX object can get back a record set?

A:
You could build an XML document out of your recordset and send that back to the server, say you had a redord set for a “user” with the following details (name, surname, age, email), you could build an xml document like this:

Code:

Byron
Tymvios
25
email@address.com

User
Someone
39
myAddy@address.com

You can add as many records as you have in your recordset, then once the client has received it you can use javascript to iterate over the ’s in the xml.

Sabari · #10 (**permalink**) 11-22-2007, 10:21 PM

Q:
What are the different frameworks available In AJAX?

A:
A good framework is “Zephyr”.
It is used with php and seems to be very easy to use.
Prototype.JS Framework is available with detailed documentation, its very easy to handle AJAX and JavaScript, Introduce $ concept its very simple, For Ajax specially u don’t need to check cross broswer, Open, Close and error handling through traditional AJAX.

Sabari · #11 (**permalink**) 11-22-2007, 10:22 PM

Q:
Who invented AJAX?

A:
Microsoft first implemented the XMLHTTPRequest object in Internet Explorer 5 for Windows as an ActiveX object. It is the term coined after this support.

Asynchronous javascript and XML. Nobody invented AJAX, Jesse James Garrett of Adaptive Path coined the phrase early 2005 - but the tech was already in place much earlier than that.

Sabari · #12 (**permalink**) 11-22-2007, 10:22 PM

Q:
Does Java have support for Comet style server-side push?

A:
Current AJAX applications use polling to communicate changes data between the server and client. Some applications, such as chat applications, stock tickers, or score boards require more immediate notifications of updates to the client. Comet is an event based low latency server side push for AJAX applications. Comet communication keeps one of the two connections available to the browser open to continously communicate events from the server to the client.

Sabari · #13 (**permalink**) 11-22-2007, 10:23 PM

Q:
Are there any security issues with AJAX?

A:
JavaScript is in plain view to the user with by selecting view source of the page. JavaScript can not access the local filesystem without the user’s permission. An AJAX interaction can only be made with the servers-side component from which the page was loaded. A proxy pattern could be used for AJAX interactions with external services.

You need to be careful not to expose your application model in such as way that your server-side components are at risk if a nefarious user to reverse engineer your application. As with any other web application, consider using HTTPS to secure the connection when confidential information is being exchanged

Sabari · #14 (**permalink**) 11-22-2007, 10:24 PM

Q:
Should I use an HTTP GET or POST for my AJAX calls?

A:
AJAX requests should use an HTTP GET request when retrieving data where the data will not change for a given request URL. An HTTP POST should be used when state is updated on the server. This is in line with HTTP idempotency recommendations and is highly recommended for a consistent web application architecture

Sabari · #15 (**permalink**) 11-22-2007, 10:27 PM

Q:
Does AJAX work with Java?

A:
Yes, Java is a great fit for AJAX! You can use Java Enterprise Edition servers to generate AJAX client pages and to serve incoming AJAX requests, manage server side state for AJAX clients, and connect AJAX clients to your enterprise resources. The JavaServer Faces component model is a great fit for defining and using AJAX components.

Sabari · #16 (**permalink**) 11-22-2007, 10:28 PM

Q:
What is AJAX?

A:
Ajax is an acronym for �Asynchronous JavaScript And XML.� Web pages are endowed with snippets of code that can access remote services (like web services) and not refresh the page. This prevents �round tripping� which is the cause for display flicker and slow response times.

Sabari · #17 (**permalink**) 11-23-2007, 07:40 AM

Q:
What AJAX framework do you recommend for PHP applications?

A:
SAjax, NAjax, FAjax.All of them are ok, but it it best to make your own to suit your needs.

What AJAX framework do you recommend for PHP applications? Answer SAjax, NAjax, FAjax.All of them are ok, but it it best to make your own to suit your needs.

Sabari · #18 (**permalink**) 11-23-2007, 07:41 AM

Q:
What are the different frameworks available In AJAX?

A:
As i have been assigned for implementing Ajax in existing Complex JSF application, my conclusion is to go for frameworks and tools if you are planning to build a fresh application.Otherwise just apply trics for incorporating ajax features.The heart of this AJAX is to validate fields without refreshing the page.else every thing thing is just javascript and CSS.

DWR

Direct Web Remoting), GWT:Google Web Toolkit (GWT), AjaxTags,AJAX4JSF,JSON-RPC-Java, AjaxAnywhere,Echo 2,and Zimbra

Sabari · #19 (**permalink**) 11-23-2007, 07:43 AM

Q:
Who is the inventor of AJAX?

A:
Colgate - Palmolive in 1947, of couse!Oh - coding? Jesse James coined the phrase early 2005 - but the tech was already in place much earlier than that. See - Ajax (programming) - Wikipedia, the free encyclopedia

Sabari · #20 (**permalink**) 11-23-2007, 07:43 AM

Q:
If I have to Automate an application developed in AJAX which tool (QTP,WinRunner)would be more useful.Does Load runner has a protocol to support AJAX.

A:
I too am having issues producing good load test data with our new AJAX app. Has anyone at least used WinRunner or QTP

IF you will record through WinRunner or QTP then you won't face any problem, but in case of Loadrunner there you can't record in a simple way you have to use special protocol i.e. "Web Click and Script" protocol. which is provided in FP4.0

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