interview questions and answers

Socket Programming Interview Questions and Answers

2010-03-10T19:26:00.000+06:00

Socket Programming Interview Questions and Answers

How does the race condition occur?
It occurs when two or more processes are reading or writing some shared data and the final result depends on who runs precisely when.

What is multiprogramming?
Multiprogramming is a rapid switching of the CPU back and forth between processes.

Name the seven layers of the OSI Model and describe them briefly.
Physical Layer - covers the physical interface between devices and the rules by which bits are passed from one to another.
Data Link Layer - attempts o make the physical link reliable and provides the means to activate, maintain, and deactivate the link.
Network Layer - provides for the transfer of information between end systems across
some sort communications network.
Transport Layer - provides a mechanism for the exchange of data between end system.
Session Layer - provides the mechanism for controlling the dialogue between applications in end systems.
Presentation Layer - defines the format of the data to be exchanged between applications and offers application programs a set of data transformation services.
Application Layer - provides a means for application programs to access the OSI environment.

What is the difference between TCP and UDP?
TCP and UDP are both transport-level protocols. TCP is designed to provide reliable communication across a variety of reliable and unreliable networks and internets.

UDP provides a connectionless service for application-level procedures. Thus, UDP is basically an unreliable service; delivery and duplicate protection are not guaranteed.

What does a socket consists of?
The combination of an IP address and a port number is called a socket.

What are some advantages and disadvantages of Java Sockets?

Advantages of Java Sockets:
Sockets are flexible and sufficient. Efficient socket based programming can be easily implemented for general communications.
Sockets cause low network traffic. Unlike HTML forms and CGI scripts that generate and transfer whole web pages for each new request, Java applets can send only necessary updated information.

Disadvantages of Java Sockets:
Security restrictions are sometimes overbearing because a Java applet running in a Web browser is only able to establish connections to the machine where it came from, and to nowhere else on the network
Despite all of the useful and helpful Java features, Socket based communications allows only to send packets of raw data between applications. Both the client-side and server-side have to provide mechanisms to make the data useful in any way.
Since the data formats and protocols remain application specific, the re-use of socket based implementations is limited.

What is the difference between a NULL pointer and a void pointer?
A NULL pointer is a pointer of any type whose value is zero. A void pointer is a pointer to an object of an unknown type, and is guaranteed to have enough bits to hold a pointer to any object. A void pointer is not guaranteed to have enough bits to point to a function (though in general practice it does).

What is encapsulation technique?
ANSWER: Hiding data within the class and making it available only through the methods. This technique is used to protect your class against accidental changes to fields, which might leave the class in an inconsistent state.

Socket Programming Interview Questions and Answers

2010-03-10T19:22:00.003+06:00

J2EE Interview Questions

2010-03-08T21:03:00.000+06:00

Question: What is J2EE?
Answer: J2EE Stands for Java 2 Enterprise Edition. J2EE is an environment for developing and deploying enterprise applications. J2EE specification is defined by Sun Microsystems Inc. The J2EE platform is one of the best platform for the development and deployment of enterprise applications. The J2EE platform is consists of a set of services, application programming interfaces (APIs), and protocols, which provides the functionality necessary for developing multi-tiered, web-based applications. You can download the J2EE SDK and development tools from http://java.sun.com/.

Question: What do you understand by a J2EE module?
Answer: A J2EE module is a software unit that consists of one or more J2EE components of the same container type along with one deployment descriptor of that type. J2EE specification defines four types of modules:
a) EJB
b) Web
c) application client and
d) resource adapter

In the J2EE applications modules can be deployed as stand-alone units. Modules can also be assembled into J2EE applications.

Question: Tell me something about J2EE component?
Answer: J2EE component is a self-contained functional software unit supported by a container and configurable at deployment time. The J2EE specification defines the following J2EE components:

Application clients and applets are components that run on the client.
Java servlet and JavaServer Pages (JSP) technology components are Web components that run on the server.
Enterprise JavaBeans (EJB) components (enterprise beans) are business components that run on the server. J2EE components are written in the Java programming language and are compiled in the same way as any program in the language. The difference between J2EE components and "standard" Java classes is that J2EE components are assembled into a J2EE application, verified to be well formed and in compliance with the J2EE specification, and deployed to production, where they are run and managed by the J2EE server or client container.

Source: J2EE v1.4 Glossary

Question: What are the contents of web module?
Answer: A web module may contain:
a) JSP files
b) Java classes
c) gif and html files and
d) web component deployment descriptors
   Question: Differentiate between .ear, .jar and .war files.
Answer: These files are simply zipped file using java jar tool. These files are created for different purposes. Here is the description of these files:
.jar files: These files are with the .jar extenstion. The .jar files contains the libraries, resources and accessories files like property files.
.war files: These files are with the .war extension. The war file contains the web application that can be deployed on the any servlet/jsp container. The .war file contains jsp, html, javascript and other files for necessary for the development of web applications.
.ear files: The .ear file contains the EJB modules of the application.

Question: What is the difference between Session Bean and Entity Bean?
Answer:
Session Bean: Session is one of the EJBs and it represents a single client inside the Application Server. Stateless session is easy to develop and its efficient. As compare to entity beans session beans require few server resources.

A session bean is similar to an interactive session and is not shared; it can have only one client, in the same way that an interactive session can have only one user. A session bean is not persistent and it is destroyed once the session terminates.

Entity Bean: An entity bean represents persistent global data from the database. Entity beans data are stored into database.

Question: Why J2EE is suitable for the development distributed multi-tiered enterprise applications?
Answer: The J2EE platform consists of multi-tiered distributed application model. J2EE applications allows the developers to design and implement the business logic into components according to business requirement. J2EE architecture allows the development of multi-tired applications and the developed applications can be installed on different machines depending on the tier in the multi-tiered J2EE environment . The J2EE application parts are:

a) Client-tier components run on the client machine.
b) Web-tier components run on the J2EE server.
c) Business-tier components run on the J2EE server and the
d) Enterprise information system (EIS)-tier software runs on the EIS servers

Question: Why do understand by a container?
Answer: Normally, thin-client multi-tiered applications are hard to write because they involve many lines of intricate code to handle transaction and state management, multithreading, resource pooling, and other complex low-level details. The component-based and platform-independent J2EE architecture makes J2EE applications easy to write because business logic is organized into reusable components. In addition, the J2EE server provides underlying services in the form of a container for every component type. Because you do not have to develop these services yourself, you are free to concentrate on solving the business problem at hand (Source: http://java.sun.com/j2ee/1.3/docs/tutorial/doc/Overview4.html ).

In short containers are the interface between a component and the low-level platform specific functionality that supports the component. The application like Web, enterprise bean, or application client component must be assembled and deployed on the J2EE container before executing.

Question: What are the services provided by a container?
Answer: The services provided by container are as follows:
a) Transaction management for the bean
b) Security for the bean
c) Persistence of the bean
d) Remote access to the bean
e) Lifecycle management of the bean
f) Database-connection pooling
g) Instance pooling for the bean

Question: What are types of J2EE clients?
Answer: J2EE clients are the software that access the services components installed on the J2EE container. Following are the J2EE clients:
a) Applets
b) Java-Web Start clients
c) Wireless clients
d) Web applications

JSP Interview : JSP Interview Questions -2

2010-03-08T20:57:00.000+06:00

Question: What is JSP Custom tags?
Answer: JSP Custom tags are user defined JSP language element. JSP custom tags are user defined tags that can encapsulate common functionality. For example you can write your own tag to access the database and performing database operations. You can also write custom tag for encapsulate both simple and complex behaviors in an easy to use syntax and greatly simplify the readability of JSP pages.

Question: What is JSP?
Answer: JavaServer Pages (JSP) technology is the Java platform technology for delivering dynamic content to web clients in a portable, secure and well-defined way. The JavaServer Pages specification extends the Java Servlet API to provide web application developers
Question: What is the role of JSP in MVC Model?
Answer: JSP is mostly used to develop the user interface, It plays are role of View in the MVC Model.
Question: What do you understand by context initialization parameters?
Answer: The context-param element contains the declaration of a web application's servlet context initialization parameters.

name

value

The Context Parameters page lets you manage parameters that are accessed through the ServletContext.getInitParameterNames and ServletContext.getInitParameter methods.
Question: Can you extend JSP technology?
Answer: JSP technology lets the programmer to extend the jsp to make the programming more easier. JSP can be extended and custom actions and tag libraries can be developed.

Question: What do you understand by JSP translation?
Answer: JSP translators generate standard Java code for a JSP page implementation class. This class is essentially a servlet class wrapped with features for JSP functionality.
Question: What you can stop the browser to cash your page?
Answer: Instead of deleting a cache, you can force the browser not to catch the page.
<%
response.setHeader("pragma","no-cache");//HTTP 1.1
response.setHeader("Cache-Control","no-cache");
response.setHeader("Cache-Control","no-store");
response.addDateHeader("Expires", -1);
response.setDateHeader("max-age", 0);
//response.setIntHeader ("Expires", -1); //prevents caching at the proxy server
response.addHeader("cache-Control", "private");

%>
put the above code in your page.
Question: What you will handle the runtime exception in your jsp page?
Answer: The errorPage attribute of the page directive can be used to catch run-time exceptions automatically and then forwarded to an error processing page.
For example:
<%@ page errorPage="customerror.jsp" %>
above code forwards the request to "customerror.jsp" page if an uncaught exception is encountered during request processing. Within "customerror.jsp", you must indicate that it is an error-processing page, via the directive: <%@ page isErrorPage="true" %>.

Best JSP Interview Questions

2010-03-08T20:50:00.001+06:00

Question: What do you understand by JSP Actions?
Answer: JSP actions are XML tags that direct the server to use existing components or control the behavior of the JSP engine. JSP Actions consist of a typical (XML-based) prefix of "jsp" followed by a colon, followed by the action name followed by one or more attribute parameters.

There are six JSP Actions:

Question: What is the difference between and
<%@ include file = ... >?.
Answer: Both the tag includes the information from one page in another. The differences are as follows:
: This is like a function call from one jsp to another jsp. It is executed ( the included page is executed and the generated html content is included in the content of calling jsp) each time the client page is accessed by the client. This approach is useful to for modularizing the web application. If the included file changed then the new content will be included in the output.

<%@ include file = ... >: In this case the content of the included file is textually embedded in the page that have <%@ include file=".."> directive. In this case in the included file changes, the changed content will not included in the output. This approach is used when the code from one jsp file required to include in multiple jsp files.

Question: What is the difference between and
response.sendRedirect(url),?.
Answer: The element forwards the request object containing the client request information from one JSP file to another file. The target file can be an HTML file, another JSP file, or a servlet, as long as it is in the same application context as the forwarding JSP file.
sendRedirect sends HTTP temporary redirect response to the browser, and browser creates a new request to go the redirected page. The response.sendRedirect kills the session variables.

Question: Identify the advantages of JSP over Servlet.

a) Embedding of Java code in HTML pages
b) Platform independence
c) Creation of database-driven Web applications
d) Server-side programming capabilities

Answer :- Embedding of Java code in HTML pages

Question: What are implicit Objects available to the JSP Page?
Answer: Implicit objects are the objects available to the JSP page. These objects are created by Web container and contain information related to a particular request, page, or application. The JSP implicit objects are:Variable Class Description
application javax.servlet.ServletContext The context for the JSP page's servlet and any Web components contained in the same application.
config javax.servlet.ServletConfig Initialization information for the JSP page's servlet.
exception java.lang.Throwable Accessible only from an error page.
out javax.servlet.jsp.JspWriter The output stream.
page java.lang.Object The instance of the JSP page's servlet processing the current request. Not typically used by JSP page authors.
pageContext javax.servlet.jsp.PageContext The context for the JSP page. Provides a single API to manage the various scoped attributes.
request Subtype of javax.servlet.ServletRequest The request triggering the execution of the JSP page.
response Subtype of javax.servlet.ServletResponse The response to be returned to the client. Not typically used by JSP page authors.
session javax.servlet.http.HttpSession The session object for the client.

Question: What are all the different scope values for the tag?
Answer: tag is used to use any java object in the jsp page. Here are the scope values for tag:
a) page
b) request
c) session and
d) application

Question: What is JSP Output Comments?
Answer: JSP Output Comments are the comments that can be viewed in the HTML source file.
Example:

and

Question: What is expression in JSP?
Answer: Expression tag is used to insert Java values directly into the output. Syntax for the Expression tag is:
<%= expression %>
An expression tag contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. The following expression tag displays time on the output:
<%=new java.util.Date()%>

Question: What types of comments are available in the JSP?
Answer: There are two types of comments are allowed in the JSP. These are hidden and output comments. A hidden comments does not appear in the generated output in the html, while output comments appear in the generated output.
Example of hidden comment:
<%-- This is hidden comment --%>
Example of output comment:

Question: What is JSP declaration?
Answer: JSP Decleratives are the JSP tag used to declare variables. Declaratives are enclosed in the <%! %> tag and ends in semi-colon. You declare variables and functions in the declaration tag and can use anywhere in the JSP

Question: What are the life-cycle methods of JSP?
Answer: Life-cycle methods of the JSP are:
a) jspInit(): The container calls the jspInit() to initialize the servlet instance. It is called before any other method, and is called only once for a servlet instance.
b)_jspService(): The container calls the _jspservice() for each request and it passes the request and the response objects. _jspService() method cann't be overridden.
c) jspDestroy(): The container calls this when its instance is about to destroyed.
The jspInit() and jspDestroy() methods can be overridden within a JSP page.

CSS Interview Questions and Answers3

2010-02-04T03:43:00.000+06:00

Three selectors: h1, .warning and #footer, what they do ?
An element points at a HTML-tag somewhere on your page. In the example above we want to style the

-tag. Note that using an element like that affects all tags with that name, so using p { margin-left: 100px; } gives all
-tags a left-margin.
Using a class is just as simple. When writing .your_class you style all tags with a class with the name “your_class”. In the example above we have .warning which will style e.g.
and , that is, any element with the class warning. Classes are used when you want to style just a few of your tags in a way, perhaps you want some of your links red? Add a class to all those links.
You need one more building block: the id. This time you style an element with the attribute “id” set to the id you have chosen. Ids work exactly like classes except for one thing; you can only have one id with a certain name in each of your HTML documents. In the example above we style
. If you look at the example it does make sense: a HTML document may contain several warnings but only one footer. Ids should be used when you want to style just one specific tag.
Using those three building blocks will take you far but when you get to more advanced layouts you might want to combine the building blocks into more advanced selectors. Just to give you two examples of what you can do: em.warning to style only those -tags with the class .warning set. You can also use #footer a to style only the links that are nested inside the tag with id “footer.
Each of the selectors has a set of declarations tied to them. Each declaration has a property, describing what we want to change and a value, what we should change it to. An example: a { color: Blue; font-size: 3em; }. You have the selector a there, so all links in your document will be styled. We have two declarations: color: Blue and font-size: 3em;. Lastly each declaration consists of two parts: the property color and the value Blue.
there is a LOT of things you can style and play with. Additionally (close to) all tags are equal in CSS, so you can set e.g. borders and colors of any element just like you could with a table if you used only HTML.

What are Style Sheets?
Style Sheets are templates, very similar to templates in desktop publishing applications, containing a collection of rules declared to various selectors (elements).

What is CSS rule 'ruleset'?
There are two types of CSS rules: ruleset and at-rule. Ruleset identifies selector or selectors and declares style which is to be attached to that selector or selectors. For example P {text-indent: 10pt} is a CSS rule. CSS rulesets consist of two parts: selector, e.g. P and declaration, e.g. {text-indent: 10pt}.

P {text-indent: 10pt} - CSS rule (ruleset)
{text-indent: 10pt} - CSS declaration
text-indent - CSS property
10pt - CSS value

'Fixed' Background?
There is the possibility to use the HTML tag bgproperties="fixed", but that is IE proprietary, and dependent upon the 'background' attribute (deprecated in HTML4).

With CSS, you can declare the background like:

BODY {
font-family : "Trebuchet MS", Verdana, Arial, Helvetica, sans-serif;
background-image: url(images/yourimage.gif);
background-repeat: no-repeat; /no-tiling background/
background-position: center;
background-attachment: fixed;
background-color: #hexcolor;
color : #hexcolor;
margin: 10px;
}

that shows a background-image in the center of the BODY element, non-scrolling and non-repeating - in IE or NN6. NN 4.xx gets the non-repeat-part right, but stuffs the picture in the upper left corner and scrolls ...

What is ID selector?
ID selector is an individually identified (named) selector to which a specific style is declared. Using the ID attribute the declared style can then be associated with one and only one HTML element per document as to differentiate it from all other elements. ID selectors are created by a character # followed by the selector's name. The name can contain characters a-z, A-Z, digits 0-9, period, hyphen, escaped characters, Unicode characters 161-255, as well as any Unicode character as a numeric code, however, they cannot start with a dash or a digit.

#abc123 {color: red; background: black}

This and only this element can be identified as abc123

What is contextual selector?
Contextual selector is a selector that addresses specific occurrence of an element. It is a string of individual selectors separated by white space, a search pattern, where only the last element in the pattern is addressed providing it matches the specified context.

TD P CODE {color: red}

The element CODE will be displayed in red but only if it occurs in the context of the element P which must occur in the context of the element TD.

TD P CODE, H1 EM {color: red}

The element CODE will be displayed in red as described above AND the element EM will also be red but only if it occurs in the context of H1

P .footnote {color: red}

Any element with CLASS footnote will be red but only if it occurs in the context of P

P .footnote [lang]{color: red}

Any element with attribute LANG will be red but only if it is classed as "footnote" and occurs in the context of P

How do I have a background image that isn't tiled?
Specify the background-repeat property as no-repeat. You can also use the background property as a shortcut for specifying multiple background-* properties at once. Here's an example:

BODY {background: #FFF url(watermark.jpg) no-repeat;}

What does \ABCD (and \ABCDE) mean?
CSS allows Unicode characters to be entered by number. For example, if a CLASS value in some Russian document contains Cyrillic letters EL PE (Unicode numbers 041B and 041F) and you want to write a style rule for that class, you can put that letter into the style sheet by writing:

.\041B\041F {font-style: italic;}
This works on all keyboards, so you don't need a Cyrillic keyboard to write CLASS names in Russian or another language that uses that script.

The digits and letters after the backslash (\) are a hexadecimal number. Hexadecimal numbers are made from ordinary digits and the letters A to F (or a to f). Unicode numbers consist of four such digits.

If the number starts with a 0, you may omit it. The above could also be written as:

.\41B\41F {font-style: italic;}
But be careful if the next letter after the three digits is also a digit or a letter a to f! This is OK: .\41B-\41F, since the dash (-) cannot be mistaken for a hexadecimal digit, but .\41B9\41F is only two letters, not three.

Four digits is the maximum, however, so if you write:
.\041B9\041F {font-style: italic;}

CSS Interview Questions and Answers2

2010-02-04T03:38:00.000+06:00
What is CSS?
1. CSS stands for Cascading Style Sheets and is a simple styling language which allows attaching style to HTML elements. Every element type as well as every occurrence of a specific element within that type can be declared an unique style, e.g. margins, positioning, color or size.

2. CSS is a web standard that describes style for XML/HTML documents.

3. CSS is a language that adds style (colors, images, borders, margins…) to your site. It’s really that simple. CSS is not used to put any content on your site, it’s just there to take the content you have and make it pretty. First thing you do is link a CSS-file to your HTML document. Do this by adding this line:

type="text/css">

The line should be placed in between your and tags. If you have several pages you could add the exact same line to all of them and they will all use the same stylesheet, but more about that later. Let’s look inside the file “style.css” we just linked to.

h1 {
font-size: 40px;
height: 200px;
}
.warning {
color: Red;
font-weight: bold;
}
#footer {
background-color: Gray;
}

4. Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g. fonts, colors, spacing) to Web documents. This is also where information meets the artistic abilities of a web-designer. CSS helps you spice up your web-page and make it look neat in wide variety of aspects.

What are Cascading Style Sheets?
A Cascading Style Sheet (CSS) is a list of statements (also known as rules) that can assign various rendering properties to HTML elements. Style rules can be specified for a single element occurrence, multiple elements, an entire document, or even multiple documents at once. It is possible to specify many different rules for an element in different locations using different methods. All these rules are collected and merged (known as a "cascading" of styles) when the document is rendered to form a single style rule for each element.
How do I center block-elements with CSS1?
There are two ways of centering block level elements:

1. By setting the properties margin-left and margin-right to auto and width to some explicit value:

BODY {width: 30em; background: cyan;}
P {width: 22em; margin-left: auto; margin-right: auto}

In this case, the left and right margins will each be four ems wide, since they equally split up the eight ems left over from (30em - 22em). Note that it was not necessary to set an explicit width for the BODY element; it was done here to keep the math clean.

Another example:

TABLE {margin-left: auto; margin-right: auto; width: 400px;}
In most legacy browsers, a table's width is by default determined by its content. In CSS-conformant browsers, the complete width of any element (including tables) defaults to the full width of its parent element's content area. As browser become more conformant, authors will need to be aware of the potential impact on their designs.
If background and color should always be set together, why do they exist as separate properties?
There are several reasons for this. First, style sheets become more legible -- both for humans and machines. The background property is already the most complex property in CSS1 and combining it with color would make it even more complex. Second, color inherits, but background doesn't and this would be a source of confusion.
What is class?
Class is a group of 1) instances of the same element to which an unique style can be attached or 2) instances of different elements to which the same style can be attached.

1) The rule P {color: red} will display red text in all paragraphs. By classifying the selector P different style can be attached to each class allowing the display of some paragraphs in one style and some other paragraphs in another style.
2) A class can also be specified without associating a specific element to it and then attached to any element which is to be styled in accordance with it's declaration. All elements to which a specific class is attached will have the same style.

To classify an element add a period to the selector followed by an unique name. The name can contain characters a-z, A-Z, digits 0-9, period, hyphen, escaped characters, Unicode characters 161-255, as well as any Unicode character as a numeric code, however, they cannot start with a dash or a digit. (Note: in HTML the value of the CLASS attribute can contain more characters). (Note: text between /* and */ are my comments).
CSS
P.name1 {color: red} /* one class of P selector */
P.name2 {color: blue} /* another class of P selector */
.name3 {color: green} /* can be attached to any element */

HTML

This paragraph will be red

This paragraph will be blue

This paragraph will be green

This list item will be green

It is a good practice to name classes according to their function than their appearance; e.g. P.fotnote and not P.green. In CSS1 only one class can be attached to a selector. CSS2 allows attaching more classes, e.g.:
P.name1.name2.name3 {declaration}

This paragraph has three classes attached

What is grouping ?
Grouping is gathering (1) into a comma separated list two or more selectors that share the same style or (2) into a semicolon separated list two or more declarations that are attached to the same selector (2).

1. The selectors LI, P with class name .first and class .footnote share the same style, e.g.:
LI {font-style: italic}
P.first {font-style: italic}
.footnote {font-style: italic}

To reduce the size of style sheets and also save some typing time they can all be grouped in one list.
LI, P.first, .footnote {font-style: italic}

2. The declarations {font-style: italic} and {color: red} can be attached to one selector, e.g.:
H2 {font-style: italic}
H2 {color: red}
and can also be grouped into one list:
H2 {font-style: italic; color: red}
What is external Style Sheet? How to link?
External Style Sheet is a template/document/file containing style information which can be linked with any number of HTML documents. This is a very convenient way of formatting the entire site as well as restyling it by editing just one file. The file is linked with HTML documents via the LINK element inside the HEAD element. Files containing style information must have extension .css, e.g. style.css.
Is CSS case sensitive?
Cascading Style Sheets (CSS) is not case sensitive. However, font families, URLs to images, and other direct references with the style sheet may be.
The trick is that if you write a document using an XML declaration and an XHTML doctype, then the CSS class names will be case sensitive for some browsers.

It is a good idea to avoid naming classes where the only difference is the case, for example:

div.myclass { ...}
div.myClass { ... }

If the DOCTYPE or XML declaration is ever removed from your pages, even by mistake, the last instance of the style will be used, regardless of case.

J2EE Interview Questions and Answers7

2010-02-03T03:07:00.000+06:00
What is entity bean ?
An enterprise bean that represents persistent data maintained in a database. An entity bean can manage its own persistence or can delegate this function to its container. An entity bean is identified by a primary key. If the container in which an entity bean is hosted crashes, the entity bean, its primary key, and any remote references survive the crash.
What is entity reference ?
A reference to an entity that is substituted for the reference when the XML document is parsed. It can reference a predefined entity such as < or reference one that is defined in the DTD. In the XML data, the reference could be to an entity that is defined in the local subset of the DTD or to an external XML file (an external entity). The DTD can also carve out a segment of DTD specifications and give it a name so that it can be reused (included) at multiple points in the DTD by defining a parameter entity.

What is error ?
A SAX parsing error is generally a validation error; in other words, it occurs when an XML document is not valid, although it can also occur if the declaration specifies an XML version that the parser cannot handle. See also fatal error, warning.

What is Extensible Markup Language ?
XML.
What is external entity ?
An entity that exists as an external XML file, which is included in the XML document using an entity reference.
What is external subset ?
That part of a DTD that is defined by references to external DTD files.
What is fatal error ?
A fatal error occurs in the SAX parser when a document is not well formed or otherwise cannot be processed. See also error, warning.
What is filter ?
An object that can transform the header or content (or both) of a request or response. Filters differ from Web components in that they usually do not themselves create responses but rather modify or adapt the requests for a resource, and modify or adapt responses from a resource. A filter should not have any dependencies on a Web resource for which it is acting as a filter so that it can be composable with more than one type of Web resource.
What is filter chain ?
A concatenation of XSLT transformations in which the output of one transformation becomes the input of the next.
What is finder method ?
A method defined in the Interview Questions - Home interface and invoked by a client to locate an entity bean.
What is form-based authentication ?
An authentication mechanism in which a Web container provides an application-specific form for logging in. This form of authentication uses Base64 encoding and can expose user names and passwords
What is general entity ?
An entity that is referenced as part of an XML document's content, as distinct from a parameter entity, which is referenced in the DTD. A general entity can be a parsed entity or an unparsed entity.
What is group ?
An authenticated set of users classified by common traits such as job title or customer profile. Groups are also associated with a set of roles, and every user that is a member of a group inherits all the roles assigned to that group.
What is handle ?
An object that identifies an enterprise bean. A client can serialize the handle and then later deserialize it to obtain a reference to the enterprise bean.
What is Interview Questions - Home handle ?
An object that can be used to obtain a reference to the Interview Questions - Home interface. A Interview Questions - Home handle can be serialized and written to stable storage and de-serialized to obtain the reference.
What is Interview Questions - Home interface ?
One of two interfaces for an enterprise bean. The Interview Questions - Home interface defines zero or more methods for managing an enterprise bean. The Interview Questions - Home interface of a session bean defines create and remove methods, whereas the Interview Questions - Home interface of an entity bean defines create, finder, and remove methods.

J2EE Interview Questions and Answers6

2010-02-03T03:02:00.000+06:00
What is EJB Home object ?
An object that provides the life-cycle operations (create, remove, find) for an enterprise bean. The class for the EJB Home object is generated by the container's deployment tools. The EJB Home object implements the enterprise bean's Home interface. The client references an EJB Home object to perform life-cycle operations on an EJB object. The client uses JNDI to locate an EJB Home object.
What is EJB JAR file ?
A JAR archive that contains an EJB module.
What is EJB module ?
A deployable unit that consists of one or more enterprise beans and an EJB deployment descriptor.

What is EJB object ?
An object whose class implements the enterprise bean's remote interface. A client never references an enterprise bean instance directly; a client always references an EJB object. The class of an EJB object is generated by a container's deployment tools.
What is EJB server ?
Software that provides services to an EJB container. For example, an EJB container typically relies on a transaction manager that is part of the EJB server to perform the two-phase commit across all the participating resource managers. The J2EE architecture assumes that an EJB container is hosted by an EJB server from the same vendor, so it does not specify the contract between these two entities. An EJB server can host one or more EJB containers.
What is EJB server provider ?
A vendor that supplies an EJB server.
What is element ?
A unit of XML data, delimited by tags. An XML element can enclose other elements.
What is empty tag ?
A tag that does not enclose any content.
What is enterprise bean ?
A J2EE component that implements a business task or business entity and is hosted by an EJB container; either an entity bean, a session bean, or a message-driven bean.
What is enterprise bean provider ?
An application developer who produces enterprise bean classes, remote and Interview Questions - Home interfaces, and deployment descriptor files, and packages them in an EJB JAR file.
What is enterprise information system ?
The applications that constitute an enterprise's existing system for handling companywide information. These applications provide an information infrastructure for an enterprise. An enterprise information system offers a well-defined set of services to its clients. These services are exposed to clients as local or remote interfaces or both. Examples of enterprise information systems include enterprise resource planning systems, mainframe transaction processing systems, and legacy database systems.
What is enterprise information system resource ?
An entity that provides enterprise information system-specific functionality to its clients. Examples are a record or set of records in a database system, a business object in an enterprise resource planning system, and a transaction program in a transaction processing system.
What is Enterprise JavaBeans (EJB) ?
A component architecture for the development and deployment of object-oriented, distributed, enterprise-level applications. Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure.
What is Enterprise JavaBeans Query Language (EJB QL) ?
Defines the queries for the finder and select methods of an entity bean having container-managed persistence. A subset of SQL92, EJB QL has extensions that allow navigation over the relationships defined in an entity bean's abstract schema.
What is an entity ?
A distinct, individual item that can be included in an XML document by referencing it. Such an entity reference can name an entity as small as a character (for example, <, which references the less-than symbol or left angle bracket, <). An entity reference can also reference an entire document, an external entity, or a collection of DTD definitions.

J2EE Interview Questions and Answers5

2010-02-03T02:57:00.002+06:00
What is deployment descriptor ?
An XML file provided with each module and J2EE application that describes how they should be deployed. The deployment descriptor directs a deployment tool to deploy a module or application with specific container options and describes specific configuration requirements that a deployer must resolve.
What is destination ?
A JMS administered object that encapsulates the identity of a JMS queue or topic. See point-to-point messaging system, publish/subscribe messaging system.

What is digest authentication ?
An authentication mechanism in which a Web application authenticates itself to a Web server by sending the server a message digest along with its HTTP request message. The digest is computed by employing a one-way hash algorithm to a concatenation of the HTTP request message and the client's password. The digest is typically much smaller than the HTTP request and doesn't contain the password.

What is distributed application ?
An application made up of distinct components running in separate runtime environments, usually on different platforms connected via a network. Typical distributed applications are two-tier (client-server), three-tier (client-middleware-server), and multitier (client-multiple middleware-multiple servers).
What is document ?
In general, an XML structure in which one or more elements contains text intermixed with subelements.
What is Document Object Model ?
An API for accessing and manipulating XML documents as tree structures. DOM provides platform-neutral, language-neutral interfaces that enables programs and scripts to dynamically access and modify content and structure in XML documents.

What is document root ?
The top-level directory of a WAR. The document root is where JSP pages, client-side classes and archives, and static Web resources are stored.
What is DTD ?
Document type definition. An optional part of the XML document prolog, as specified by the XML standard. The DTD specifies constraints on the valid tags and tag sequences that can be in the document. The DTD has a number of shortcomings, however, and this has led to various schema proposals. For example, the DTD entry says that the XML element called username contains parsed character data-that is, text alone, with no other structural elements under it. The DTD includes both the local subset, defined in the current file, and the external subset, which consists of the definitions contained in external DTD files that are referenced in the local subset using a parameter entity.
What is durable subscription ?
In a JMS publish/subscribe messaging system, a subscription that continues to exist whether or not there is a current active subscriber object. If there is no active subscriber, the JMS provider retains the subscription's messages until they are received by the subscription or until they expire.
What is EAR file ?
Enterprise Archive file. A JAR archive that contains a J2EE application.
What is ebXML ?
Electronic Business XML. A group of specifications designed to enable enterprises to conduct business through the exchange of XML-based messages. It is sponsored by OASIS and the United Nations Centre for the Facilitation of Procedures and Practices in Administration, Commerce and Transport (U.N./CEFACT).
What is EJB ?
Enterprise JavaBeans.
What is EJB container ?
A container that implements the EJB component contract of the J2EE architecture. This contract specifies a runtime environment for enterprise beans that includes security, concurrency, life-cycle management, transactions, deployment, naming, and other services. An EJB container is provided by an EJB or J2EE server.
What is EJB container provider ?
A vendor that supplies an EJB container.
What is EJB context ?
A vendor that supplies an EJB container. An object that allows an enterprise bean to invoke services provided by the container and to obtain the information about the caller of a client-invoked method.

J2EE Interview Questions and Answers4

2010-02-03T02:55:00.002+06:00
What is container-managed sign-on ?
The mechanism whereby security information needed for signing on to a resource is supplied by the container.
What is container-managed transaction ?
A transaction whose boundaries are defined by an EJB container. An entity bean must use container-managed transactions.
What is content ?
In an XML document, the part that occurs after the prolog, including the root element and everything it contains.

What is context attribute ?
An object bound into the context associated with a servlet.
What is context root ?
A name that gets mapped to the document root of a Web application.
What is conversational state ?
The field values of a session bean plus the transitive closure of the objects reachable from the bean's fields. The transitive closure of a bean is defined in terms of the serialization protocol for the Java programming language, that is, the fields that would be stored by serializing the bean instance.
What is CORBA ?
Common Object Request Broker Architecture. A language-independent distributed object model specified by the OMG.
What is create method ?
A method defined in the Interview Questions - Home interface and invoked by a client to create an enterprise bean.
What is credentials ?
The information describing the security attributes of a principal.
What is CSS ?
Cascading style sheet. A stylesheet used with HTML and XML documents to add a style to all elements marked with a particular tag, for the direction of browsers or other presentation mechanisms.
What is CTS ?
Compatibility test suite. A suite of compatibility tests for verifying that a J2EE product complies with the J2EE platform specification.
What is data ?
The contents of an element in an XML stream, generally used when the element does not contain any subelements. When it does, the term content is generally used. When the only text in an XML structure is contained in simple elements and when elements that have subelements have little or no data mixed in, then that structure is often thought of as XML data, as opposed to an XML document.
What is DDP ?
Document-driven programming. The use of XML to define applications.
What is declaration ?
The very first thing in an XML document, which declares it as XML. The minimal declaration is . The declaration is part of the document prolog.
What is declarative security ?
Mechanisms used in an application that are expressed in a declarative syntax in a deployment descriptor.
What is delegation ?
An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.
What is deployer ?
A person who installs J2EE modules and applications into an operational environment.
What is deployment ?
The process whereby software is installed into an operational environment.

J2EE Interview Questions and Answers3

2010-02-03T02:51:00.002+06:00
What is binding (JavaServer Faces technology) ?
Wiring UI components to back-end data sources such as backing bean properties.
What is build file ?
The XML file that contains one or more asant targets. A target is a set of tasks you want to be executed. When starting asant, you can select which targets you want to have executed. When no target is given, the project's default target is executed.

What is business logic ?
The code that implements the functionality of an application. In the Enterprise JavaBeans architecture, this logic is implemented by the methods of an enterprise bean.
What is business method ?
A method of an enterprise bean that implements the business logic or rules of an application.
What is callback methods ?
Component methods called by the container to notify the component of important events in its life cycle.
What is caller ?
Same as caller principal.
What is caller principal ?
The principal that identifies the invoker of the enterprise bean method.
What is cascade delete ?
A deletion that triggers another deletion. A cascade delete can be specified for an entity bean that has container-managed persistence.
What is CDATA ?
A predefined XML tag for character data that means "don't interpret these characters," as opposed to parsed character data (PCDATA), in which the normal rules of XML syntax apply. CDATA sections are typically used to show examples of XML syntax.
What is certificate authority ?
A trusted organization that issues public key certificates and provides identification to the bearer.
What is client-certificate authentication ?
An authentication mechanism that uses HTTP over SSL, in which the server and, optionally, the client authenticate each other with a public key certificate that conforms to a standard that is defined by X.509 Public Key Infrastructure.
What is comment ?
In an XML document, text that is ignored unless the parser is specifically told to recognize it.
What is commit ?
The point in a transaction when all updates to any resources involved in the transaction are made permanent.
What is component contract ?
The contract between a J2EE component and its container. The contract includes life-cycle management of the component, a context interface that the instance uses to obtain various information and services from its container, and a list of services that every container must provide for its components.
What is component-managed sign-on ?
A mechanism whereby security information needed for signing on to a resource is provided by an application component.
What is connector ?
A standard extension mechanism for containers that provides connectivity to enterprise information systems. A connector is specific to an enterprise information system and consists of a resource adapter and application development tools for enterprise information system connectivity. The resource adapter is plugged in to a container through its support for system-level contracts defined in the Connector architecture.
What is container-managed persistence ?
The mechanism whereby data transfer between an entity bean's variables and a resource manager is managed by the entity bean's container.

J2EE Interview Questions and Answers2

2010-02-03T02:48:00.000+06:00

What is "application client" ?
A first-tier J2EE client component that executes in its own Java virtual machine. Application clients have access to some J2EE platform APIs.
What is "application client container" ?
A container that supports application client components.

What is "application client module" ?
A software unit that consists of one or more classes and an application client deployment descriptor.
What is "application component provider" ?
A vendor that provides the Java classes that implement components' methods, JSP page definitions, and any required deployment descriptors.
What is "application configuration resource file" ?
An XML file used to configure resources for a Java Server Faces application, to define navigation rules for the application, and to register converters, Validator, listeners, renders, and components with the application.
What is "archiving" ?
The process of saving the state of an object and restoring it.
What is "asant" ?
A Java-based build tool that can be extended using Java classes. The configuration files are XML-based, calling out a target tree where various tasks get executed.
What is "attribute"?
A qualifier on an XML tag that provides additional information.
What is authentication ?
The process that verifies the identity of a user, device, or other entity in a computer system, usually as a prerequisite to allowing access to resources in a system. The Java servlet specification requires three types of authentication-basic, form-based, and mutual-and supports digest authentication.
What is authorization ?
The process by which access to a method or resource is determined. Authorization depends on the determination of whether the principal associated with a request through authentication is in a given security role. A security role is a logical grouping of users defined by the person who assembles the application. A deployer maps security roles to security identities. Security identities may be principals or groups in the operational environment.
What is authorization constraint ?
An authorization rule that determines who is permitted to access a Web resource collection.
What is B2B ?
B2B stands for Business-to-business.
What is backing bean ?
A JavaBeans component that corresponds to a JSP page that includes JavaServer Faces components. The backing bean defines properties for the components on the page and methods that perform processing for the component. This processing includes event handling, validation, and processing associated with navigation.
What is basic authentication ?
An authentication mechanism in which a Web server authenticates an entity via a user name and password obtained using the Web application's built-in authentication mechanism.
What is bean-managed persistence ?
The mechanism whereby data transfer between an entity bean's variables and a resource manager is managed by the entity bean.
What is bean-managed transaction ?
A transaction whose boundaries are defined by an enterprise bean.
What is binding (XML) ?
Generating the code needed to process a well-defined portion of XML data.

J2EE Interview Questions and Answers1

2010-02-03T02:24:00.000+06:00
What is J2EE?
J2EE is an environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multitier, web-based applications.
What is the J2EE module?
A J2EE module consists of one or more J2EE components for the same container type and one component deployment descriptor of that type.

What are the components of J2EE application?
A J2EE component is a self-contained functional software unit that is assembled into a J2EE application with its related classes and files and communicates with other components. The J2EE specification defines the following J2EE components:
   Application clients and applets are client components.
   Java Servlet and JavaServer PagesTM (JSPTM) technology components are web components.
   Enterprise JavaBeansTM (EJBTM) components (enterprise beans) are business components.
   Resource adapter components provided by EIS and tool vendors.
What are the four types of J2EE modules?
1. Application client module
2. Web module
3. Enterprise JavaBeans module
4. Resource adapter module
What does application client module contain?
The application client module contains:
--class files,
--an application client deployment descriptor.
Application client modules are packaged as JAR files with a .jar extension.
What does web module contain?
The web module contains:
--JSP files,
--class files for servlets,
--GIF and HTML files, and
--a Web deployment descriptor.
Web modules are packaged as JAR files with a .war (Web ARchive) extension.
What are the differences between Ear, Jar and War files? Under what circumstances should we use each one?
There are no structural differences between the files; they are all archived using zip-jar compression. However, they are intended for different purposes.
--Jar files (files with a .jar extension) are intended to hold generic libraries of Java classes, resources, auxiliary files, etc.
--War files (files with a .war extension) are intended to contain complete Web applications. In this context, a Web application is defined as a single group of files, classes, resources, .jar files that can be packaged and accessed as one servlet context.
--Ear files (files with a .ear extension) are intended to contain complete enterprise applications. In this context, an enterprise application is defined as a collection of .jar files, resources, classes, and multiple Web applications.
Each type of file (.jar, .war, .ear) is processed uniquely by application servers, servlet containers, EJB containers, etc.
What is the difference between Session bean and Entity bean ?
The Session bean and Entity bean are two main parts of EJB container.
Session Bean
--represents a workflow on behalf of a client
--one-to-one logical mapping to a client.
--created and destroyed by a client
--not permanent objects
--lives its EJB container(generally) does not survive system shut down
--two types: stateless and stateful beans
Entity Bean
--represents persistent data and behavior of this data
--can be shared among multiple clients
--persists across multiple invocations
--findable permanent objects
--outlives its EJB container, survives system shutdown
--two types: container managed persistence(CMP) and bean managed persistence(BMP)
What is "applet" ?
A J2EE component that typically executes in a Web browser but can execute in a variety of other applications or devices that support the applet programming model.
What is "applet container" ?
A container that includes support for the applet programming model.
What is "application assembler" ?
A person who combines J2EE components and modules into deployable application units.

J2ME Interview Questions and Answers6

2010-02-03T01:44:00.002+06:00
What is Tomcat ?
Tomcat is a reference implementation of the Java servlet and JavaServer Pages (JSP) specifications. It is intended as a platform for developing and testing servlets.

What is UDDI ?
Universal Description, Discovery, and Integration (UDDI) is an XML-based standard for describing, publishing, and finding Web services. UDDI is a specification for a distributed registry of Web services.
What is UMTS
Developed by Nortel Networks, Universal Mobile Telecommunications Service (UMTS) is a standard that will provide cellular users a consistent set of technologies no matter where they are located worldwide. UMTS utilizes W-CDMA technology.

What is VLR
The Visitor Location Register (VLR) is a database that contains temporary information about subscribers.
What is WAE
The Wireless Application Environment (WAE) provides a application framework for small devices. WAE leverages other technologies such as WAP, WTP, and WSP.
What is WAP
Wireless Application Protocol (WAP) is a protocol for transmitting data between servers and clients (usually small wireless devices like mobile phones). WAP is analogous to HTTP in the World Wide Web. Many mobile phones include WAP browser software to allow users access to Internet WAP sites.
What is WAP Gateway
A WAP Gateway acts as a bridge allowing WAP devices to communicate with other networks (namely the Internet).
What is W-CDMA
Wideband Code-Division Multiple Access (W-CDMA), also known as IMT-2000, is a 3rd generation wireless technology. Supports speeds up to 384Kbps on a wide-area network, or 2Mbps locally.
What is WDP
Wireless Datagram Protocol (WDP) works as the transport layer of WAP. WDP processes datagrams from upper layers to formats required by different physical datapaths, bearers, that may be for example GSM SMS or CDMA Packet Data. WDP is adapted to the bearers available in the device so upper layers don't need to care about the physical level.
What is WMA
The Wireless Messaging API (WMA) is a set of classes for sending and receiving Short Message Service messages. See also SMS.
What is WML
The Wireless Markup Language (WML) is a simple language used to create applications for small wireless devices like mobile phones. WML is analogous to HTML in the World Wide Web.
What is WMLScript
WMLScript is a subset of the JavaScript scripting language designed as part of the WAP standard to provide a convenient mechanism to access mobile phone's peripheral functions.
What is WSP
Wireless Session Protocol (WSP) implements session services of WAP. Sessions can be connection-oriented and connectionless and they may be suspended and resumed at will.
What is WTLS
Wireless Transport Layer Security protocal (WTLS) does all cryptography oriented features of WAP. WTLS handles encryption/decryption, user authentication and data integrity. WTLS is based on the fixed network Transport Layer Security protocal (TLS), formerly known as Secure Sockets Layer (SSL).
What is WTP
Wireless Transaction Protocol (WTP) is WAP's transaction protocol that works between the session protocol WSP and security protocol WTLS. WTP chops data packets into lower level datagrams and concatenates received datagrams into useful data. WTP also keeps track of received and sent packets and does re-transmissions and acknowledgment sending when needed.

J2ME Interview Questions and Answers5

2010-02-03T01:38:00.002+06:00
What is Provisioning ?
In telecommunications terms, provisioning means to provide telecommunications services to a user. This includes providing all necessary hardware, software, and wiring or transmission devices.
What is PSTN ?
The public service telephone network (PSTN) is the traditional, land-line based system for exchanging phone calls.

What is RMI
Remote method invocation (RMI) is a feature of J2SE that enables Java objects running in one virtual machine to invoke methods of Java objects running in another virtual machine, seamlessly.
What is RMI OP
The RMI Optional Package (RMI OP) is a subset of J2SE 1.3's RMI functionality used in CDC-based profiles that incorporate the Foundation Profile, such as the Personal Basis Profile and the Personal Profile. The RMIOP cannot be used with CLDC-based profiles because they lack object serialization and other important features found only in CDC-based profiles. RMIOP supports most of the J2SE RMI functionality, including the Java Remote Method Protocol, marshalled objects, distributed garbage collection, registry-based object lookup, and network class loading, but not HTTP tunneling or the Java 1.1 stub protocol.
What is RMI Profile
The RMI Profile is a J2ME profile specification designed to support Java's Remote Method Invocation (RMI) distributed object system. Devices implementing the RMI Profile will be able to interoperate via RMI with other Java devices, including Java 2, Standard Edition. The RMI Profile is based on the Foundation Profile, which in turn is based on CDC.
What is RMS
The Record Management System (RMS) is a simple record-oriented database that allows a MIDlet to persistently store information and retrieve it later. Different MIDlets can also use the RMS to share data.
What is SDK
A Software Development Kit (SDK) is a set of tools used to develop applications for a particular platform. An SDK typically contains a compiler, linker, and debugger. It may also contain libraries and documentation for APIs.
What is SIM
A Subscriber Identity Module (SIM) is a stripped-down smart card containing information about the identity of a cell-phone subscriber, and subscriber authentication and service information. Because the SIM uniquely identifies the subscriber and is portable among handsets, the user can move it from one kind of phone to another, facilitating international roaming.
What is SMS
Short Message Service (SMS) is a point-to-point service similar to paging for sending text messages of up to 160 characters to mobile phones.
What is SOAP
The Simple Object Access Protocol (SOAP) is an XML- based protocol that allows objects of any type to communicated in a distributed environment. SOAP is used in developing Web Services.
What is SSL
Secure Sockets Layer (SSL) is a socket protocol that encrypts data sent over the network and provides authentication for the socket endpoints.
What is T9
T9 is a text input method for mobile phones and other small devices. It replaces the "multi-tap" input method by guessing the word that you are trying to enter. T9 may be embedded in a device by the manufacturer. Note that even if the device supports T9, the Java implementation may or may not use it. Check your documentation for details.
What is TDMA
Time Division Multiple Access (TDMA) is a second-generation modulation standard using bandwidth allocated in the 800 MHz, 900 MHz, and 1900MHz ranges.
What is Telematics
Telematics is a location-based service that routes event notification and control data over wireless networks to and from mobile devices installed in automobiles. Telematics makes use of GPS technology to track vehicle latitude and longitude, and displays maps in LED consoles mounted in dashboards. It connects to remote processing centers that turn provide server-side Internet and voice services, as well as access to database resources.

J2ME Interview Questions and Answers4

2010-02-03T01:32:00.001+06:00
What is Modulation ?
Modulation is the method by which a high-frequency digital signal is grafted onto a lower-frequency analog wave, so that digital packets are able to ride piggyback on the analog airwave.

What is MSC ?
A Mobile Switching Center (MSC) is a unit within a cellular phone network that automatically coordinates and switches calls in a given cell. It monitors each caller's signal strength, and when a signal begins to fade, it hands off the call to another MSC that's better positioned to manage the call.

What is Obfuscation
Obfuscation is a technique used to complicate code. Obfuscation makes code harder to understand when it is de-compiled, but it typically has no affect on the functionality of the code. Obfuscation programs can be used to protect Java programs by making them harder to reverse-engineer.
What is optional package
An optional package is a set of J2ME APIs providing services in a specific area, such as database access or multimedia. Unlike a profile, it does not define a complete application environment, but rather is used in conjunction with a configuration or a profile. It extends the runtime environment to support device capabilities that are not universal enough to be defined as part of a profile or that need to be shared by different profiles. J2ME RMI and the Mobile Media RMI are examples of optional packages.
What is OTA
Over The Air (OTA) refers to any wireless networking technology.
What is PCS
Personal Communications Service (PCS) is a suite of second-generation, digitally modulated mobile-communications interfaces that includes TDMA, CDMA, and GSM. PCS serves as an umbrella term for second-generation wireless technologies operating in the 1900MHz range
What is PDAP
The Personal Digital Assistant Profile (PDAP) is a J2ME profile specification designed for small platforms such as PalmOS devices. You can think of PDAs as being larger than mobile phones but smaller than set-top boxes. PDAP is built on top of CLDC and will specify user interface and persistent storage APIs. PDAP is currently being developed using the Java Community Process (JCP).
What is PDC
Personal Digital Cellular (PDC) is a Japanese standard for wireless communications.
What is PDCP
Parallel and Distributed Computing Practices (PDCP) are often used to describe computer systems that are spread over many devices on a network (wired or wireless) where many nodes process data simultaneously.
What is Personal Profile
The Personal Profile is a J2ME profile specification. Layered on the Foundation Profile and CDC, the Personal Profile will be the next generation of PersonalJava technology. The specification is currently in development under the Java Community Process (JCP).
What is PersonalJava
PersonalJava is a Java environment based on the Java virtual machine1 (JVM) and a set of APIs similar to a JDK 1.1 environment. It includes the Touchable Look and Feel (also called Truffle), a graphic toolkit that is optimized for consumer devices with a touch sensitive screen. PersonalJava will be included in J2ME in the upcoming Personal Profile, which is built on CDC.
What is PNG
Portable Network Graphics (PNG) is an image format offering lossless compression and storage flexibility. The MIDP specification requires implementations to recognize certain types of PNG images.
What is POSE
Palm OS Emulator (POSE).
What is PRC
Palm Resource Code (PRC) is the file format for Palm OS applications.
What is preverification
Due to memory and processing power available on a device, the verification process of classes are split into two processes. The first process is the preverification which is off-device and done using the preverify tool. The second process is verification which is done on-device.
What is profile
A profile is a set of APIs added to a configuration to support specific uses of a mobile device. Along with its underlying configuration, a profile defines a complete, and usually self-contained, general-purpose application environment. Profiles often, but not always, define APIs for user interface and persistence; the MIDP profile, based on the CLDC configuration, fits this pattern. Profiles may be supersets or subsets of other profiles; the Personal Basis Profile is a subset of the Personal Profile and a superset of the Foundation Profile. See also configuration, optional package.

J2ME Interview Questions and Answers3

2010-02-03T01:28:00.000+06:00
What is JDBC for CDC/FP ?
The JDBC Optional Package for CDC/Foundation Profile (JDBCOP for CDC/FP) is an API that enables mobile Java applications to communicate with relational database servers using a subset of J2SE's Java Database Connectivity. This optional package is a strict subset of JDBC 3.0 that excludes some of JDBC's advanced and server-oriented features, such as pooled connections and array types. It's meant for use with the Foundation Profile or its supersets.

What is JSR
Java Specification Request (JSR) is the actual description of proposed and final specifications for the Java platform. JSRs are reviewed by the JCP and the public before a final release of a specification is made.
What is KittyHawk
KittyHawk is a set of APIs used by LG Telecom on its IBook and p520 devices. KittyHawk is based on CLDC. It is conceptually similar to MIDP but the two APIs are incompatible.
What is KJava
KJava is an outdated term for J2ME. It comes from an early package of Java software for PalmOS, released at the 2000 JavaOne show. The classes for that release were packaged in the com.sun.kjava package.
What is kSOAP
kSOAP is a SOAP API suitable for the J2ME, based on kXML.
What is kXML
The kXML project provides a small footprint XML parser that can be used with J2ME.
What is KVM
The KVM is a compact Java virtual machine (JVM) that is designed for small devices. It supports a subset of the features of the JVM. For example, the KVM does not support floating-point operations and object finalization. The CLDC specifies use of the KVM. According to folklore, the 'K' in KVM stands for kilobyte, signifying that the KVM runs in kilobytes of memory as opposed to megabytes.
What is LAN
A Local Area Network (LAN) is a group of devices connected with various communications technologies in a small geographic area. Ethernet is the most widely-used LAN technology. Communication on a LAN can either be with Peer-to-Peer devices or Client-Server devices.
What is LCDUI
LCDUI is a shorthand way of referring to the MIDP user interface APIs, contained in the javax.microedition.lcdui package. Strictly speaking, LCDUI stands for Liquid Crystal Display User Interface. It's a user interface toolkit for small device screens which are commonly LCD screens.
What is MExE
The Mobile Execution Environment (MExE) is a specification created by the 3GPP which details an applicatio n environment for next generation mobile devices. MExE consists of a variety of technologies including WAP, J2ME, CLDC and MIDP.
What is MIDlet
A MIDlet is an application written for MIDP. MIDlet applications are subclasses of the javax.microedition.midlet.MIDlet class that is defined by MIDP.
What is MIDlet suite
MIDlets are packaged and distributed as MIDlet suites. A MIDlet suite can contain one or more MIDlets. The MIDlet suite consists of two files, an application descriptor file with a .jad extension and an archive file with a .jar file. The descriptor lists the archive file name, the names and class names for each MIDlet in the suite, and other information. The archive file contains the MIDlet classes and resource files.

What is MIDP
The Mobile Information Device Profile (MIDP) is a specification for a J2ME profile. It is layered on top of CLDC and adds APIs for application life cycle, user interface, networking, and persistent storage.
What is MIDP-NG
The Next Generation MIDP specification is currently under development by the Java Community Process. Planned improvements include XML parsing and cryptographic support.
What is Mobitex
Mobitex is a packet-switched, narrowband PCS network, designed for wide-area wireless data communications. It was developed in 1984 by Eritel, an Ericsson subsidiary, a nd there are now over 30 Mobitex networks in operation worldwide.

J2ME Interview Questions and Answers2

2010-02-02T22:08:00.000+06:00
What is ETSI ?
The European Telecommunications Standards Institute (ETSI) is a non-profit organization that establishes telecommunications standards for Europe.

What is FDMA ?
Frequency-division multiple-access (FDMA) is a mechanism for sharing a radio frequency band among multiple users by dividing it into a number of smaller bands.

What is Foundation Profile ?
The Foundation Profile is a J2ME profile specification that builds on CDC. It adds additional classes and interfaces to the CDC APIs but does not go so far as to specify user interface APIs, persistent storage, or application life cycle. Other J2ME profiles build on the CDC/Foundation combination: for example, the Personal Profile and the RMI Profile both build on the Foundation Profile.

What is Generic Connection Framework ?
The Generic Connection Framework (GCF) makes it easy for wireless devices to make network connections. It is part of CLDC and CDC and resides in the javax.microedition.io package.

What is GPRS ?
The General Packet Radio System (GPRS) is the next generation of GSM. It will be the basis of 3G networks in Europe and elsewhere.

What is GSM ?
The Global System for Mobile Communications (GSM) is a wireless network system that is widely used in Europe, Asia, and Australia. GSM is used at three different frequencies: GSM900 and GSM1800 are used in Europe, Asia, and Australia, while GSM1900 is deployed in North America and other parts of the world.

What is HLR ?
The Home Location Register (HLR) is a database for permanent storage of subscriber data and service profiles.

What is HTTPS ?
Hyper Text Transfer Protocol Secure sockets (HTTPS) is a protocol for transmission of encrypted hypertext over Secure Sockets Layer.

What is i-appli ?
Sometimes called "Java for i-mode", i-appli is a Java environment based on CLDC. It is used on handsets in NTT DoCoMo's i-mode service. While i-appli is similar to MIDP, it was developed before the MIDP specification was finished and the two APIs are incompatible.

What is IDE ?
An Integrated Development Environment (IDE) provides a programming environment as a single application. IDEs typically bundle a compiler, debugger, and GUI builder tog ether. Forte for Java is Sun's Java IDE.

What is iDEN ?
The Integrated Dispatch Enhanced Network (iDEN) is a wireless network system developed by Motorola. Various carriers support iDEN networks around the world: Nextel is one of the largest carriers, with networks covering North and South America.

What is i-mode ?
A standard used by Japanese wireless devices to access cHTML (compact HTML) Web sites and display animated GIFs and other multimedia content.

What is 3G ?
Third generation (3G) wireless networks will offer faster data transfer rates than current networks. The first generation of wireless (1G) was analog cellular. The second generation (2G) is digital cellular, featuring integrated voice and data communications. So-called 2.5G networks offer incremental speed increases. 3G networks will offer dramatically improved data transfer rates, enabling new wireless applications such as streaming media.

What is 3GPP ?
The 3rd Generation Partnership Project (3GPP) is a global collaboration between 6 partners: ARIB, CWTS, ETSI, T1, TTA, and TTC. The group aims to develop a globally accepted 3rd-generation mobile system based on GSM.

What is Java Card ?
The Java Card specification allows Java technology to run on smart cards and other small devices. The Java Card API is compatible with formal international standards, such as, ISO7816, and industry-specific standards, such as, Europay/Master Card/Visa (EMV).

What is JavaHQ ?
JavaHQ is the Java platform control center on your Palm OS device.

What is JCP ?
The Java Community Process (JCP) an open organization of international Java developers and licensees who develop and revise Java technology specifications, reference implementations, and technology compatibility kits through a formal process.

J2ME Interview Questions and Answers1

2010-02-02T21:58:00.002+06:00
What is J2ME ?
Java 2, Micro Edition is a group of specifications and technologies that pertain to Java on small devices. The J2ME moniker covers a wide range of devices, from pagers and mobile telephones through set-top boxes and car navigation systems. The J2ME world is divided into configurations and profiles, specifications that describe a Java environment for a specific class of device.

What is J2ME WTK ?
The J2ME Wireless Toolkit is a set of tools that provides developers with an emulation environment, documentation and examples for developing Java applications for small devices. The J2ME WTK is based on the Connected Limited Device Configuration (CLDC) and Mobile Information Device Profile (MIDP) reference implementations, and can be tightly integrated with Forte for Java

What is 802.11 ?
802.11 is a group of specifications for wireless networks developed by the Institute of Electrical and Electronics Engineers (IEEE). 802.11 uses the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.

What is API ?
An Application Programming Interface (API) is a set of classes that you can use in your own application. Sometimes called libraries or modules, APIs enable you to write an application without reinventing common pieces of code. For example, a networking API is something your application can use to make network connections, without your ever having to understand the underlying code. 5. What is AMPS

Advanced Mobile Phone Service (AMPS) is a first-generation analog, circuit-switched cellular phone network. Originally operating in the 800 MHz band, service was later expanded to include transmissions in the 1900 MHz band, the VHF range in which most wireless carriers operate. Because AMPS uses analog signals, it cannot transmit digital signals and cannot transport data packets without assistance from newer technologies such as TDMA and CDMA.

What is CDC ?

The Connected Device Configuration (CDC) is a specification for a J2ME configuration. Conceptually, CDC deals with devices with more memory and processing power than CLDC; it is for devices with an always-on network connection and a minimum of 2 MB of memory available for the Java system.

What is CDMA ?
Code-Division Multiple Access (CDMA) is a cellular technology widely used in North America. There are currently three CDMA standards: CDMA One, CDMA2000 and W-CDMA. CDMA technology uses UHF 800Mhz-1.9Ghz frequencies and bandwidth ranges from 115Kbs to 2Mbps.

What is CDMA One ?
Also know as IS-95, CDMA One is a 2nd generation wireless technology. Supports speeds from 14.4Kbps to 115K bps.

What is CDMA2000 ?
Also known as IS-136, CDMA2000 is a 3rd generation wireless technology. Supports speeds ranging from 144Kbps to 2Mbps.

What is CDPD ?
Developed by Nortel Networks, Cellular Digital Packet Data (CDPD) is an open standard for supporting wireless Internet access from cellular devices. CDPD also supports Multicast, which allows content providers to efficiently broadcast information to many devices at the same time.

What is cHTML ?
Compact HTML (cHTML) is a subset of HTML which is designed for small devices. The major features of HTML that are excluded from cHTML are: JPEG image, Table, Image map, Multiple character fonts and styles, Background color and image, Frame and Style sheet.

What is CLDC ?
The Connected, Limited Device Configuration (CLDC) is a specification for a J2ME configuration. The CLDC is for devices with less than 512 KB or RAM available for the Java system and an intermittent (limited) network connection. It specifies a stripped-down Java virtual machine1 called the KVM as well as several APIs for fundamental application services. Three packages are minimalist versions of the J2SE java.lang, java.io, and java.util packages. A fourth package, javax.microedition.io, implements the Generic Connection Framework, a generalized API for making network connections.

What is configuration ?
In J2ME, a configuration defines the minimum Java runtime environment for a family of devices: the combination of a Java virtual machine (either the standard J2SE virtual machine or a much more limited version called the CLDC VM) and a core set of APIs. CDC and CLDC are configurations. See also profile, optional package.

What is CVM ?
The Compact Virtual Machine (CVM) is an optimized Java virtual machine1 (JVM) that is used by the CDC.

What is Deck ?
A deck is a collection of one or more WML cards that can be downloaded, to a mobile phone, as a single entity.

What is EDGE ?
Enhanced Data GSM Environment (EDGE) is a new, faster version of GSM. EDGE is designed to support transfer rates up to 384Kbps and enable the delivery of video and other high-bandwidth applications. EDGE is the result of a joint effort between TDMA operators, vendors and carriers and the GSM Alliance.

50 COMMON INTERVIEW Q&A

2010-01-21T02:48:00.000+06:00
Review these typical interview questions and think about how you would
answer them. Read the questions listed; you will also find some
strategy suggestions with it.

(Excerpted from the book The Accelerated Job Search by Wayne D. Ford, Ph.D, published by The Management Advantage, Inc.)

1. Tell me about yourself:
The most often asked question in interviews. You need to have a short
statement prepared in your mind. Be careful that it does not sound
rehearsed. Limit it to work-related items unless instructed otherwise.
Talk about things you have done and jobs you have held that relate to
the position you are interviewing for. Start with the item farthest
back and work up to the present.

2. Why did you leave your last job?
Stay positive regardless of the circumstances. Never refer to a major
problem with management and never speak ill of supervisors, co-workers
or the organization. If you do, you will be the one looking bad. Keep
smiling and talk about leaving for a positive reason such as an
opportunity, a chance to do something special or other forward-looking
reasons.

3. What experience do you have in this field?
Speak about specifics that relate to the position you are applying for.
If you do not have specific experience, get as close as you can.

4. Do you consider yourself successful?
You should always answer yes and briefly explain why. A good
explanation is that you have set goals, and you have met some and are
on track to achieve the others.

5. What do co-workers say about you?
Be prepared with a quote or two from co-workers. Either a specific
statement or a paraphrase will work. Jill Clark, a co-worker at Smith
Company, always said I was the hardest workers she had ever known. It
is as powerful as Jill having said it at the interview herself.

6. What do you know about this organization?
This question is one reason to do some research on the organization
before the interview. Find out where they have been and where they are
going. What are the current issues and who are the major players?

7. What have you done to improve your knowledge in the last year?
Try to include improvement activities that relate to the job. A wide
variety of activities can be mentioned as positive self-improvement.
Have some good ones handy to mention.

8. Are you applying for other jobs?
Be honest but do not spend a lot of time in this area. Keep the focus
on this job and what you can do for this organization. Anything else is
a distraction.

9. Why do you want to work for this organization?
This may take some thought and certainly, should be based on the
research you have done on the organization. Sincerity is extremely
important here and will easily be sensed. Relate it to your long-term
career goals.

10. Do you know anyone who works for us?
Be aware of the policy on relatives working for the organization. This
can affect your answer even though they asked about friends not
relatives. Be careful to mention a friend only if they are well thought
of.

11. What kind of salary do you need?
A loaded question. A nasty little game that you will probably lose if
you answer first. So, do not answer it. Instead, say something like,
That’s a tough question. Can you tell me the range for this position?
In most cases, the interviewer, taken off guard, will tell you. If not,
say that it can depend on the details of the job. Then give a wide
range.

12. Are you a team player?
You are, of course, a team player. Be sure to have examples ready.
Specifics that show you often perform for the good of the team rather
than for yourself are good evidence of your team attitude. Do not brag,
just say it in a matter-of-fact tone. This is a key point.

13. How long would you expect to work for us if hired?
Specifics here are not good. Something like this should work: I’d like
it to be a long time. Or As long as we both feel I’m doing a good job.

14. Have you ever had to fire anyone? How did you feel about that?
This is serious. Do not make light of it or in any way seem like you
like to fire people. At the same time, you will do it when it is the
right thing to do. When it comes to the organization versus the
individual who has created a harmful situation, you will protect the
organization. Remember firing is not the same as layoff or reduction in
force.

15. What is your philosophy towards work?
The interviewer is not looking for a long or flowery dissertation here.
Do you have strong feelings that the job gets done? Yes. That’s the
type of answer that works best here. Short and positive, showing a
benefit to the organization.

16. If you had enough money to retire right now, would you?
Answer yes if you would. But since you need to work, this is the type
of work you prefer. Do not say yes if you do not mean it.

17. Have you ever been asked to leave a position?
If you have not, say no. If you have, be honest, brief and avoid saying
negative things about the people or organization involved.

18. Explain how you would be an asset to this organization
You should be anxious for this question. It gives you a chance to
highlight your best points as they relate to the position being
discussed. Give a little advance thought to this relationship.

19. Why should we hire you?
Point out how your assets meet what the organization needs. Do not
mention any other candidates to make a comparison.

20. Tell me about a suggestion you have made
Have a good one ready. Be sure and use a suggestion that was accepted
and was then considered successful. One related to the type of work
applied for is a real plus.

21. What irritates you about co-workers?
This is a trap question. Think real hard but fail to come up with
anything that irritates you. A short statement that you seem to get
along with folks is great.

22. What is your greatest strength?
Numerous answers are good, just stay positive. A few good examples:
Your ability to prioritize, Your problem-solving skills, Your ability
to work under pressure, Your ability to focus on projects, Your
professional expertise, Your leadership skills, Your positive attitude

23. Tell me about your dream job.
Stay away from a specific job. You cannot win. If you say the job you
are contending for is it, you strain credibility. If you say another
job is it, you plant the suspicion that you will be dissatisfied with
this position if hired. The best is to stay genetic and say something
like: A job where I love the work, like the people, can contribute and
can’t wait to get to work.

24. Why do you think you would do well at this job?
Give several reasons and include skills, experience and interest.

25. What are you looking for in a job?
See answer # 23

26. What kind of person would you refuse to work with?
Do not be trivial. It would take disloyalty to the organization,
violence or lawbreaking to get you to object. Minor objections will
label you as a whiner.

27. What is more important to you: the money or the work?
Money is always important, but the work is the most important. There is
no better answer.

28. What would your previous supervisor say your strongest point is?
There are numerous good possibilities:
Loyalty, Energy, Positive attitude, Leadership, Team player, Expertise,
Initiative, Patience, Hard work, Creativity, Problem solver

29. Tell me about a problem you had with a supervisor
Biggest trap of all. This is a test to see if you will speak ill of
your boss. If you fall for it and tell about a problem with a former
boss, you may well below the interview right there. Stay positive and
develop a poor memory about any trouble with a supervisor.

30. What has disappointed you about a job?
Don’t get trivial or negative. Safe areas are few but can include:
Not enough of a challenge. You were laid off in a reduction Company did
not win a contract, which would have given you more responsibility.

31. Tell me about your ability to work under pressure.
You may say that you thrive under certain types of pressure. Give an
example that relates to the type of position applied for.

32. Do your skills match this job or another job more closely?
Probably this one. Do not give fuel to the suspicion that you may want
another job more than this one.

33. What motivates you to do your best on the job?
This is a personal trait that only you can say, but good examples are:
Challenge, Achievement, Recognition

34. Are you willing to work overtime? Nights? Weekends?
This is up to you. Be totally honest.

35. How would you know you were successful on this job?
Several ways are good measures:
You set high standards for yourself and meet them. Your outcomes are a
success.Your boss tell you that you are successful

36. Would you be willing to relocate if required?
You should be clear on this with your family prior to the interview if
you think there is a chance it may come up. Do not say yes just to get
the job if the real answer is no. This can create a lot of problems
later on in your career. Be honest at this point and save yourself
future grief.

37. Are you willing to put the interests of the organization ahead ofyour own?
This is a straight loyalty and dedication question. Do not worry about
the deep ethical and philosophical implications. Just say yes.

38. Describe your management style.
Try to avoid labels. Some of the more common labels, like progressive,
salesman or consensus, can have several meanings or descriptions
depending on which management expert you listen to. The situational
style is safe, because it says you will manage according to the
situation, instead of one size fits all.

39. What have you learned from mistakes on the job?
Here you have to come up with something or you strain credibility. Make
it small, well intentioned mistake with a positive lesson learned. An
example would be working too far ahead of colleagues on a project and
thus throwing coordination off.

40. Do you have any blind spots?
Trick question. If you know about blind spots, they are no longer blind
spots. Do not reveal any personal areas of concern here. Let them do
their own discovery on your bad points. Do not hand it to them.

41. If you were hiring a person for this job, what would you look for?
Be careful to mention traits that are needed and that you have.

42. Do you think you are overqualified for this position?
Regardless of your qualifications, state that you are very well
qualified for the position.

43. How do you propose to compensate for your lack of experience?
First, if you have experience that the interviewer does not know about,
bring that up: Then, point out (if true) that you are a hard working
quick learner.

44. What qualities do you look for in a boss?
Be generic and positive. Safe qualities are knowledgeable, a sense of
humor, fair, loyal to subordinates and holder of high standards. All
bosses think they have these traits.

45. Tell me about a time when you helped resolve a dispute betweenothers.
Pick a specific incident. Concentrate on your problem solving technique
and not the dispute you settled.

46. What position do you prefer on a team working on a project?
Be honest. If you are comfortable in different roles, point that out.

47. Describe your work ethic.
Emphasize benefits to the organization. Things like, determination to
get the job done and work hard but enjoy your work are good.

48. What has been your biggest professional disappointment?
Be sure that you refer to something that was beyond your control. Show
acceptance and no negative feelings.

49. Tell me about the most fun you have had on the job.
Talk about having fun by accomplishing something for the organization.

50. Do you have any questions for me?
Always have some questions prepared. Questions prepared where you will be an asset to the organization are good. How soon will I be able to be productive? and What type of projects will I be able to assist on? are
examples.

QA Interview Questions and Answers – for Software QA tester and QA analyst

2010-01-21T02:31:00.000+06:00
QA software tester plans & conducts various test processes to new developed software in order to verify that the software programs functions according to the initial requirements.

The compatibility, functionality and the quality of the product is tested according to pre established quality standards and guidelines.

The difference between QA analysts (QA engineers) and products/software QA testers is that the quality assurance analysts focus on improving and minimizing defects and preventing mistakes from accruing in the first place, while QA testers perform Quality Control tests in order to find bugs and diagnose errors per pre/post product release.

This article provides wide ranging of interview questions for QA positions such as – QA engineers, Quality Assurance analysts and SQA testers and suggests answers for the same.
QA testing interview questions and answers – software QA interview questions with answers

The following questions are good for QA engineers, quality assurance QA analysts and SQA, software QA testers’ professionals:

• What is the meaning of traceability matrix?
Answer – Tractability matrix is used to cross check the test scripts per the requirement of the test cases.

• What is the difference between verification and validation?
Answer – Verification is based on verifying the functionality of a new system while validation is based on testing scenarios and test cases of a new system.

• Describe the role of software QA in terms of the test plan – scope of work, monitoring reliability and project implementation.
Answer – You should explain how you determine the timing for system testing, what to test and when do you finalize the testing?

• Describe test strategy – What are the steps you generally take to test any software? What is the first test in software testing process?
Answer – Unit testing is the first test that is usually done by the developers. You have to explain the methods you use for preparing test data per the test cases requirements that you have defined. Also, tell about the process of preparing test scripts, loops and conditions for the test scripts that you prepared in order to ensure the quality control process.

• Have you led or managed ISO registration process?
Answer – Describe the principals of the ISO audit you’ve participated?

• Have you been conducting audits on a regular basis?
Answer – If you did, then describe the goals of the audit, how you’ve monitored the audit findings and how you’ve controlled the corrective actions.

• Tell us about ISO 90xx documentation control and corrective actions?
Answer – If you familiar with ISO, you probably know that ISO contains a set of document control and specific process for corrective actions.

• Did you write Quality Manual or product Release notes?
Answer – If you wrote such a QM document, you can describe the basic standards of the Quality Manuals. Product release notes contains – bug history and status of bugs.

• What is your knowledge on data analysis and statistical process control?

• What are the QA software tools, automation tools and statistical software you use? What are the advantages of these tools?
Answer – Provide list of software such as: SAS and SWOT Manager or any software and automated testing emulation system, ATE, that you were using. You may also explain how these tools enhance reliability.

• Describe a Gaga R&R
Answer – R & R stands for reproducibility and repeatability. It is a system measurement error that determines the percentage of error, the type of error and its affection on the system.

• Describe a bug life cycle.
Answer – bug life cycle consists of several statuses of the bug during its life cycle such as: open, deferred, rejected, solved, fixed, reopen, closed. You can talk about the process flow and how you monitor and determine each bug status.

• What is the difference between a Bug and a Defect?
Answer – Bug is a deviation from the expected result that can be fixed and solved, while a defect is a problem in the application algorithm or the mechanism that leads to consistent failure or an error that requires a massive change.

AJAX Questions and Answers: 5

2010-01-12T12:10:00.000+06:00

41 :: Is it possible to set session variables from JavaScript?
It's not possible to set any session variables directly from JavaScript as it is purely a client side technology. You can use AJAX though to asyncronously...

42 :: Is the server or the client in control in AJAX?
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.
Both methods are viable depending on what you are trying to accomplish. I tend to prefer spreading the control across the client and server.

43 :: Is the XMLHttpRequest object part of a W3C standard?
No. Or not yet. It is part of the DOM Level 3 Load and Save Specification proposal.

44 :: Should I consider AJAX?
AJAX definitely has the buzz right now, but it might not be the right thing for you. AJAX is limited to the latest browsers, exposes browser compatibility issues, and requires new skill-sets for many. There is a good blog entry by Alex Bosworth on AJAX Mistakes which is a good read before you jump full force into AJAX.
On the other hand you can achieve highly interactive rich web applications that are responsive and appear really fast. While it is debatable as to whether an AJAX based application is really faster, the user feels a sense of immediacy because they are given active feedback while data is exchanged in the background. If you are an early adopter and can handle the browser compatibility issues, and are willing to learn some more skills, then AJAX is for you. It may be prudent to start off AJAX-ifying a small portion or component of your application first. We all love technology, but just remember the purpose of AJAX is to enhance your user's experience and not hinder

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

46 :: Should I use XML or text, JavaScript, or HTML as a return type?
It depends. Clearly the 'X' in AJAX stands for XML, but several AJAX proponents are quick to point out that nothing in AJAX, per se, precludes using other types of payload, such as, JavaScript, HTML, or plain text.

* XML - Web Services and AJAX seem made for one another. You can use client-side API's for downloading and parsing the XML content from RESTful Web Services. (However be mindful with some SOAP based Web Services architectures the payloads can get quite large and complex, and therefore may be inappropriate with AJAX techniqes.)
* Plain Text - In this case server-generated text may be injected into a document or evaluated by client-side logic.
* JavaScript - This is an extension to the plain text case with the exception that a server-side component passes a fragment of JavaScript including JavaScript object declarations. Using the JavaScript eval() function you can then create the objects on the client. JavaScript Object Notation (JSON), which is a JavaScript object based data exchange specification, relies on this technique.
* HTML - Injecting server-generated HTML fragments directly into a document is generally a very effective AJAX technique. However, it can be complicated keeping the server-side component in sync with what is displayed on the client.

Mashup is a popular term for creating a completely new web application by combining the content from disparate Web Services and other online API'

47 :: Some of the Google examples you cite don’t use XML at all. Do I have to use XML and/or XSLT in an Ajax application?
No. XML is the most fully-developed means of getting data in and out of an Ajax client, but there’s no reason you couldn’t accomplish the same effects using a technology like JavaScript Object Notation or any similar means of structuring data for interchange.

Mashup is a popular term for creating a completely new web application by combining the content from disparate Web Services and other online API's. A good example of a mashup is housingmaps.com which graphically combines housing want-ads from craiglist.org and maps from maps.google.com.

48 :: Techniques for asynchronous server communication have been around for years. What makes Ajax a “new” approach?
What’s new is the prominent use of these techniques in real-world applications to change the fundamental interaction model of the Web. Ajax is taking hold now because these technologies and the industry’s understanding of how to deploy them most effectively have taken time to develop.

49 :: Does Ajax have significant accessibility or browser compatibility limitations?
Does Ajax have significant accessibility or browser compatibility limitations? Do Ajax applications break the back button? Is Ajax compatible with REST? Are there security considerations with Ajax development? Can Ajax applications be made to work for users who have JavaScript turned off?

The answer to all of these questions is “maybe”. Many developers are already working on ways to address these concerns. We think there’s more work to be done to determine all the limitations of Ajax, and we expect the Ajax development community to uncover more issues like these along the way.

50 :: Does AJAX work with Java?
Absolutely. 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.

AJAX Questions and Answers: 4

2010-01-12T12:08:00.000+06:00

31 :: Is Adaptive Path selling Ajax components or trademarking the name? Where can I download it?
Ajax isn’t something you can download. It’s an approach — a way of thinking about the architecture of web applications using certain technologies. Neither the Ajax name nor the approach are proprietary to Adaptive Path.

32 :: Is Ajax a technology platform or is it an architectural style?
It’s both. Ajax is a set of technologies being used together in a particular way.

33 :: Is AJAX code cross browser compatible?
Not totally. Most browsers offer a native XMLHttpRequest JavaScript object, while another one (Internet Explorer) require you to get it as an ActiveX object.

34 :: Is Ajax just another name for XMLHttpRequest?
No. XMLHttpRequest is only part of the Ajax equation. XMLHttpRequest is the technical component that makes the asynchronous server communication possible; Ajax is our name for the overall approach described in the article, which relies not only on XMLHttpRequest, but on CSS, DOM, and other technologies.

35 :: How do I test my AJAX code?
There is a port of JUnit for client-side JavaScript called JsUnit used to test AJAX code

36 :: How do I provide internationalized AJAX interactions?
Just because you are using XML does not mean you can properly send and receive localized content using AJAX requests. To provide internationalized AJAX components you need to do the following:

* Set the charset of the page to an encoding that is supported by your target languages. I tend to use UTF-8 because it covers the most languages. The following meta declaration in a HTML/JSP page will set the content type:

* In the page JavaScript make sure to encode any parameters sent to the server. JavaScript provides the escape() function which returns Unicode escape strings in which localized text will appear in hexadecimal format. For more details on JavaScript encoding see Comparing escape(), encodeURI(), and encodeURIComponent().
* On the server-side component set the character encoding using the HttpServletRequest.setCharacterEncoding() method. Before you access the localized parameter using the HttpServletRequest.getParameter() call. In the case of UTF this would be request.setCharactherEncoding("UTF-8");.
A server-side component returning AJAX responses needs to set the encoding of the response to the same encoding used in the page.
response.setContentType("text/xml;charset=;UTF-8");
response.getWriter().write(" invalid ");

37 :: How do I send an image using AJAX?
While it may appear that images are being sent when using AJAX with an application like Google Maps what is really happening is that the URLs of images are being send as the response of an AJAX request and those URLs are being set using DHTML.
In this example an XML document is returned from an AJAX interaction and the category bar is populated.

1
Books
Fun to read
books_icon.gif

2
Electronics
Must have gadgets
electronics.gif

Notice that the image-url element contains the location of the URL for the image representing a category. The callback method of an AJAX interaction will parse the response XML document and call the addCategory function for each category included in the response XML document. The addCategory function looks up a table row element "categoryTable" in body of the page and adds a row to the element which contains the image.

38 :: How do I submit a form or a part of a form without a page refresh?
When creating a form make sure that the "form" element "onSubmit" attribute is set to a JavaScript function that returns false.

You can also submit data by associating a function with a form button in a similar way.

Note that the form "onSubmit" attribute is still set. If the user hits the enter key in the text field the form will be submitted so you still need to handle that case.
When updating the page it is recommend you wait to make sure that the AJAX update of the form data was successful before updating the data in the page. Otherwise, the data may not properly update and the user may not know. I like to provide an informative message when doing a partial update and upon a successful AJAX interaction I will then update the page

39 :: How does HTML_AJAX compare with the XAJAX project at Sourceforge?
XAJAX uses XML as a transport for data between the webpage and server, and you don't write your own javascript data handlers to manipulate the data received from the server. Instead you use a php class and built in javascript methods, a combination that works very similiar to the HTML_AJAX_Action class and haSerializer combo. XAJAX is designed for simplicity and ease of use.
HTML_AJAX allows for multiple transmission types for your ajax data - such as urlencoding, json, phpserialized, plain text, with others planned, and has a system you can use to write your own serializers to meet your specific needs. HTML_AJAX has a class to help generate javascript (HTML_AJAX_Helper) similiar to ruby on rail's javascript helper (although it isn't complete), and an action system similiar to XAJAX's "action pump" that allows you to avoid writing javascript data handlers if you desire.
But it also has the ability to write your own data handling routines, automatically register classes and methods using a server "proxy" script, do different types of callbacks including grabbing remote urls, choose between sync and async requests, has iframe xmlhttprequest emulation fallback capabilities for users with old browsers or disabled activeX, and is in active development with more features planned (see the Road Map for details)

40 :: How do I handle the back and forward buttons in AJAX?
While you could go out and create a custom solution that tracks the current state on your application I recommend you leave this to the experts. Dojo addresses the navigation in a browser neutral way as can be seen in the JavaScript example below.

function updateOnServer(oldId, oldValue,
itemId, itemValue) {
var bindArgs = {
url: "faces/ajax-dlabel-update",
method: "post",
content: {"component-id": itemId, "component-value":
itemValue},
mimetype: "text/xml",
load: function(type, data) {
processUpdateResponse(data);
},
backButton: function() {
alert("old itemid was " + oldId);
},
forwardButton: function(){
alert("forward we must go!");
}
};
dojo.io.bind(bindArgs);
}

The example above will update a value on the server using dojo.io.bind() with a function as a property that is responsible for dealing with the browser back button event. As a developer you are capable of restoring the value to the oldValue or taking any other action that you see fit.

AJAX Questions and Answers: 3

2010-01-12T12:05:00.000+06:00

21 :: What kinds of applications is Ajax best suited for?
We don’t know yet. Because this is a relatively new approach, our understanding of where Ajax can best be applied is still in its infancy. Sometimes the traditional web application model is the most appropriate solution to a problem.

22 :: What parts of the HTML_AJAX API are stable?
We don't have a list right now, but most of the API is stable as of 0.3.0. There should be no major changes at this point, though there will be lots of new additions.

23 :: What about applets and plugins?
Don't be too quick to dump your plugin or applet based portions of your application. While AJAX and DHTML can do drag and drop and other advanced user interfaces there still limitations especially when it comes to browser support. Plugins and applets have been around for a while and have been able to make AJAX like requests for years. Applets provide a great set of UI components and APIs that provide developers literally anything.
Many people disregard applets or plugins because there is a startup time to initialize the plugin and there is no guarantee that the needed version of a plugin of JVM is installed. Plugins and applets may not be as capable of manipulating the page DOM. If you are in a uniform environment or can depend on a specific JVM or plugin version being available (such as in a corporate environment) a plugin or applet solution is great.
One thing to consider is a mix of AJAX and applets or plugins. Flickr uses a combination of AJAX interactions/DHTML for labeling pictures and user interaction and a plugin for manipulating photos and photo sets to provide a great user experience. If you design your server-side components well they can talk to both types of clients.

24 :: How Ajax is Different?
An Ajax application eliminates the start-stop-start-stop nature of interaction on the Web by introducing an intermediary — an Ajax engine — between the user and the server. It seems like adding a layer to the application would make it less responsive, but the opposite is true.

Instead of loading a webpage, at the start of the session, the browser loads an Ajax engine — written in JavaScript and usually tucked away in a hidden frame. This engine is responsible for both rendering the interface the user sees and communicating with the server on the user’s behalf. The Ajax engine allows the user’s interaction with the application to happen asynchronously — independent of communication with the server. So the user is never staring at a blank browser window and an hourglass icon, waiting around for the server to do something.

25 :: How do we abort the current XMLHttpRequest in AJAX?
Just call the abort() method on the request to abort the current XMLHttpRequest in AJAX.

26 :: How do I access data from other domains to create a mashup with Java?
From your JavaScript clients you can access data in other domains if the return data is provide in JSON format. In essence you can create a JavaScript client that runs operates using data from a different server. This technique is know as JSON with Padding or JSONP. There are questions as to whether this method is secure as you are retrieving data from outside your domain and allowing it to be executed in the context of your domain. Not all data from third parties is accessible as JSON and in some cases you may want an extra level of protection. With Java you can provide a proxy to third party services using a web component such as a servlet. This proxy can manage the communication with a third party service and provide the data to your clients in a format of your choosing. You can also cache data at your proxy and reduce trips to service. For more on using a Java proxy to create mashups see The XmlHttpProxy Client for Java.

27 :: How do we create a thread to do AJAX polling?
JavaScript does not have threads. JavaScript functions are called when an event happens in a page such as the page is loaded, a mouse click, or a form element gains focus. You can create a timer using the setTimeout which takes a function name and time in milliseconds as arguments. You can then loop by calling the same function as can be seen in the JavaScript example below.

function checkForMessage() {
// start AJAX interaction with processCallback as the callback function
}

// callback for the request
function processCallback() {

// do post processing

setTimeout("checkForMessage()", 10000);
}

Notice that the checkForMessage will continue to loop indefinitely. You may want to vary the increment the interval based on activity in the page or your use cases. You may also choose to have logic that would break out of the loop based on some AJAX response processing condition.

28 :: How do we debug JavaScript?
There are not that many tools out there that will support both client-side and server-side debugging. I am certain this will change as AJAX applications proliferate. I currently do my client-side and server-side debugging separately. Below is some information on the client-side debuggers on some of the commonly used browsers.

* Firefox/Mozilla/Netscape - Have a built in debugger Venkman which can be helpful but there is a Firefox add on known as FireBug which provides all the information and AJAX developer would ever need including the ability to inspect the browser DOM, console access to the JavaScript runtime in the browser, and the ability to see the HTTP requests and responses (including those made by an XMLHttpRequest). I tend to develop my applications initially on Firefox using Firebug then venture out to the other browsers.
* Safari - Has a debugger which needs to be enabled. See the Safari FAQ for details.
* Internet Explorer - There is MSDN Documentation on debugging JavaScript. A developer toolbar for Internet Explorer may also be helpful.

While debuggers help a common technique knowing as "Alert Debugging" may be used. In this case you place "alert()" function calls inline much like you would a System.out.println. While a little primitive it works for most basic cases. Some frameworks such as Dojo provide APIs for tracking debug statements.

29 :: How do we get the XMLHttpRequest object in AJAX?
Depending upon the browser...
if (window.ActiveXObject)
{
// Internet Explorer http_request = new ActiveXObject("Microsoft.XMLHTTP");
}
else if.

30 :: How do we handle concurrent AJAX requests?
With JavaScript you can have more than one AJAX request processing at a single time. In order to insure the proper post processing of code it is recommended that you use JavaScript Closures. The example below shows an XMLHttpRequest object abstracted by a JavaScript object called AJAXInteraction. As arguments you pass in the URL to call and the function to call when the processing is done.

function AJAXInteraction(url, callback) {
var req = init();
req.onreadystatechange = processRequest;

function init() {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
return new ActiveXObject("Microsoft.XMLHTTP");
}
}

function processRequest () {
if (req.readyState == 4) {
if (req.status == 200) {
if (callback) callback(req.responseXML);
}
}
}

this.doGet = function() {
req.open("GET", url, true);
req.send(null);
}

this.doPost = function(body) {
req.open("POST", url, true);
req.setRequestHeader("Content-Type", "
application/x-www-form-urlencoded");
req.send(body);
}
}

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