Interview Material

XML Interview Questions Answers

XML Interview Question - 1 : -

When constructing an XML DTD, how do you create an external entity reference in an attribute value?

XML Interview Answer - 1 : -

Every interview session should have at least one trick question. Although possible when using SGML, XML DTDs don't support defining external entity references in attribute values. It's more important for the candidate to respond to this question in a logical way than than the candidate know the somewhat obscure answer.

XML Interview Question - 2 : -

Why is XML such an important development?

XML Interview Answer - 2 : -

XML allows the flexible development of user-defined document types. It provides a robust, non-proprietary, persistent, and verifiable file format for the storage and transmission of text and data both on and off the Web; and it removes the more complex options of SGML, making it easier to program for.

Describe the role that XSL can play when dynamically generating HTML pages from a relational database.
Even if candidates have never participated in a project involving this type of architecture, they should recognize it as one of the common uses of XML. Querying a database and then formatting the result set so that it can be validated as an XML document allows developers to translate the data into an HTML table using XSLT rules. Consequently, the format of the resulting HTML table can be modified without changing the database query or application code since the document rendering logic is isolated to the XSLT rules.

XML Interview Question - 3 : -

Which parts of an XML document are case-sensitive?

XML Interview Answer - 3 : -

All of it, both markup and text. This is significantly different from HTML and most other SGML applications. It was done to allow markup in non-Latin-alphabet languages, and to obviate problems with case-folding in writing systems which are caseless.
* Element type names are case-sensitive: you must follow whatever combination of upper- or lower-case you use to define them (either by first usage or in a DTD or Schema). So you can't say <BODY>…</body>: upper- and lower-case must match; thus <Img/>, <IMG/>, and <img/> are three different element types;
* For well-formed XML documents with no DTD, the first occurrence of an element type name defines the casing;
* Attribute names are also case-sensitive, for example the two width attributes in <PIC width="7in"/> and <PIC WIDTH="6in"/> (if they occurred in the same file) are separate attributes, because of the different case of width and WIDTH;
* Attribute values are also case-sensitive. CDATA values (eg Url="MyFile.SGML") always have been, but NAME types (ID and IDREF attributes, and token list attributes) are now case-sensitive as well;
* All general and parameter entity names (eg Á), and your data content (text), are case-sensitive as always.

XML Interview Question - 4 : -

Who is responsible for XML?

XML Interview Answer - 4 : -

XML is a project of the World Wide Web Consortium (W3C), and the development of the specification is supervised by an XML Working Group. A Special Interest Group of co-opted contributors and experts from various fields contributed comments and reviews by email.
XML is a public format: it is not a proprietary development of any company, although the membership of the WG and the SIG represented companies as well as research and academic institutions. The v1.0 specification was accepted by the W3C as a Recommendation on Feb 10, 1998.

XML Interview Question - 5 : -

How would you build a search engine for large volumes of XML data?

XML Interview Answer - 5 : -

answer is to build a full-text search and handle the data similarly to the way Internet portals handle HTML pages. Others consider XML as a standard way of transferring structured data between disparate systems. These candidates often describe some scheme of importing XML into a relational or object database and relying on the database's engine for searching. Lastly, candidates that have worked with vendors specializing in this area often say that the best way the handle this situation is to use a third party software package optimized for XML data.

XML Interview Question - 6 : -

What is XML?

XML Interview Answer - 6 : -

XML is the Extensible Markup Language. It improves the functionality of the Web by letting you identify your information in a more accurate, flexible, and adaptable way.
It is extensible because it is not a fixed format like HTML (which is a single, predefined markup language). Instead, XML is actually a metalanguage—a language for describing other languages—which lets you design your own markup languages for limitless different types of documents. XML can do this because it's written in SGML, the international standard metalanguage for text document markup (ISO 8879).

XML Interview Question - 7 : -

What is SOAP and how does it relate to XML?

XML Interview Answer - 7 : -

The Simple Object Access Protocol (SOAP) uses XML to define a protocol for the exchange of information in distributed computing environments. SOAP consists of three components: an envelope, a set of encoding rules, and a convention for representing remote procedure calls. Unless experience with SOAP is a direct requirement for the open position, knowing the specifics of the protocol, or how it can be used in conjunction with HTTP, is not as important as identifying it as a natural application of XML

XML Interview Question - 8 : -

Why not just carry on extending HTML?

XML Interview Answer - 8 : -

HTML was already overburdened with dozens of interesting but incompatible inventions from different manufacturers, because it provides only one way of describing your information.
XML allows groups of people or organizations to question C.13, create their own customized markup applications for exchanging information in their domain (music, chemistry, electronics, hill-walking, finance, surfing, petroleum geology, linguistics, cooking, knitting, stellar cartography, history, engineering, rabbit-keeping, question C.19, mathematics, genealogy, etc).
HTML is now well beyond the limit of its usefulness as a way of describing information, and while it will continue to play an important role for the content it currently represents, many new applications require a more robust and flexible infrastructure.

XML Interview Question - 9 : -

What is DOM and how does it relate to XML?

XML Interview Answer - 9 : -

The Document Object Model (DOM) is an interface specification maintained by the W3C DOM Workgroup that defines an application independent mechanism to access, parse, or update XML data. In simple terms it is a hierarchical model that allows developers to manipulate XML documents easily Any developer that has worked extensively with XML should be able to discuss the concept and use of DOM objects freely. Additionally, it is not unreasonable to expect advanced candidates to thoroughly understand its internal workings and be able to explain how DOM differs from an event-based interface like SAX.

XML Interview Question - 10 : -

What does an XML document actually look like (inside)?

XML Interview Answer - 10 : -

The basic structure of XML is similar to other applications of SGML, including HTML. The basic components can be seen in the following examples. An XML document starts with a Prolog:
1. The XML Declaration

which specifies that this is an XML document;
2. Optionally a Document Type Declaration

which identifies the type of document and says where the Document Type Description (DTD) is stored;
The Prolog is followed by the document instance:
1. A root element, which is the outermost (top level) element (start-tag plus end-tag) which encloses everything else: in the examples below the root elements are conversation and titlepage;
2. A structured mix of descriptive or prescriptive elements enclosing the character data content (text), and optionally any attributes (‘name=value’ pairs) inside some start-tags.
XML documents can be very simple, with straightforward nested markup of your own design:
<?xml version="1.0" standalone="yes"?>
<conversation><br>
<greeting>Hello, world!</greeting>
<response>Stop the planet, I want to get
off!</response>
</conversation>
Or they can be more complicated, with a Schema or question C.11, Document Type Description (DTD) or internal subset (local DTD changes in [square brackets]), and an arbitrarily complex nested structure:
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE titlepage
SYSTEM "http://www.google.bar/dtds/typo.dtd"
[<!ENTITY % active.links "INCLUDE">]>
<titlepage id="BG12273624">
<white-space type="vertical" amount="36"/>
<title font="Baskerville" alignment="centered"
size="24/30">Hello, world!</title>
<white-space type="vertical" amount="12"/>

<image location="http://www.google.bar/fleuron.eps"
type="URI" alignment="centered"/>
<white-space type="vertical" amount="24"/>
<author font="Baskerville" size=&quo

XML Interview Question - 11 : -

Give a few examples of types of applications that can benefit from using XML.

XML Interview Answer - 11 : -

There are literally thousands of applications that can benefit from XML technologies. The point of this question is not to have the candidate rattle off a laundry list of projects that they have worked on, but, rather, to allow the candidate to explain the rationale for choosing XML by citing a few real world examples. For instance, one appropriate answer is that XML allows content management systems to store documents independently of their format, which thereby reduces data redundancy. Another answer relates to B2B exchanges or supply chain management systems. In these instances, XML provides a mechanism for multiple companies to exchange data according to an agreed upon set of rules. A third common response involves wireless applications that require WML to render data on hand held devices.

XML Interview Question - 12 : -

Do I have to know HTML or SGML before I learn XML?

XML Interview Answer - 12 : -

No, although it's useful because a lot of XML terminology and practice derives from two decades' experience of SGML.
Be aware that ‘knowing HTML’ is not the same as ‘understanding SGML’. Although HTML was written as an SGML application, browsers ignore most of it (which is why so many useful things don't work), so just because something is done a certain way in HTML browsers does not mean it's correct, least of all in XML.

XML Interview Question - 13 : -

Where should I use XML?

XML Interview Answer - 13 : -

Its goal is to enable generic SGML to be served, received, and processed on the Web in the way that is now possible with HTML. XML has been designed for ease of implementation and for interoperability with both SGML and HTML.
Despite early attempts, browsers never allowed other SGML, only HTML (although there were plugins), and they allowed it (even encouraged it) to be corrupted or broken, which held development back for over a decade by making it impossible to program for it reliably. XML fixes that by making it compulsory to stick to the rules, and by making the rules much simpler than SGML.
But XML is not just for Web pages: in fact it's very rarely used for Web pages on its own because browsers still don't provide reliable support for formatting and transforming it. Common uses for XML include:
Information identification
because you can define your own markup, you can define meaningful names for all your information items. Information storage
because XML is portable and non-proprietary, it can be used to store textual information across any platform. Because it is backed by an international standard, it will remain accessible and processable as a data format. Information structure
XML can therefore be used to store and identify any kind of (hierarchical) information structure, especially for long, deep, or complex document sets or data sources, making it ideal for an information-management back-end to serving the Web. This is its most common Web application, with a transformation system to serve it as HTML until such time as browsers are able to handle XML consistently. Publishing
The original goal of XML as defined in the quotation at the start of this section. Combining the three previous topics (identity, storage, structure) means it is possible to get all the benefits of robust document management and control (with XML) and publish to the Web (as HTML) as well as to paper (as PDF) and to other formats (e.g. Braille, Audio, etc) from a single source document by using the appropriate style sheets. Messaging and data transfer
XML is also very heavily used for enclosing or encapsulating information in order to pass it between different computing systems which would otherwise be unable to communicate. By providing a lingua franca for data identity and structure, it provides a common envelope for inter-process communication (messaging). Web services
Building on al

XML Interview Question - 14 : -

What is SGML?

XML Interview Answer - 14 : -

SGML is the Standard Generalized Markup Language (ISO 8879:1986), the international standard for defining descriptions of the structure of different types of electronic document.
SGML is very large, powerful, and complex. It has been in heavy industrial and commercial use for nearly two decades, and there is a significant body of expertise and software to go with it.
XML is a lightweight cut-down version of SGML which keeps enough of its functionality to make it useful but removes all the optional features which made SGML too complex to program for in a Web environment.

XML Interview Question - 15 : -

Is there an XML version of HTML?

XML Interview Answer - 15 : -

Yes, the W3C recommends using XHTML which is ‘a reformulation of HTML 4 in XML 1.0’. This specification defines HTML as an XML application, and provides three DTDs corresponding to the ones defined by HTML 4.* (Strict, Transitional, and Frameset).
The semantics of the elements and their attributes are as defined in the W3C Recommendation for HTML 4. These semantics provide the foundation for future extensibility of XHTML. Compatibility with existing HTML browsers is possible by following a small set of guidelines (see the W3C site).