XML Interview Questions and Answers
Related differences
Ques 6. Who is responsible for XML?
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.
Ques 7. How to validate an XML document?
- XML documents must have a root element.
- XML elements must have a closing tag.
- XML tags are case sensitive.
- XML elements must be properly nested.
- XML attribute values must be quoted.
Ques 8. Give a few examples of types of applications that can benefit from using XML?
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.
Ques 9. Why should I use XML?
Here are a few reasons for using XML (in no particular order). Not all of these will apply to your own requirements, and you may have additional reasons not mentioned here.
- XML can be used to describe and identify information accurately and unambiguously, in a way that computers can be programmed to understand (well, at least manipulate as if they could understand).
- XML allows documents which are all the same type to be created consistently and without structural errors, because it provides a standardised way of describing, controlling, or allowing/disallowing particular types of document structure. [Note that this has absolutely nothing whatever to do with formatting, appearance, or the actual text content of your documents, only the structure of them.]
- XML provides a robust and durable format for information storage and transmission. Robust because it is based on a proven standard, and can thus be tested and verified; durable because it uses plain-text file formats which will outlast proprietary binary ones.
Ques 10. Which parts of an XML document are case-sensitive?
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 <employee>), and your data content (text), are case-sensitive as always.
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