Software Code Help - XML Interview Question

What is XSLT and Xpath?

Raj Shekhar — Fri, 22 Jan 2010 05:39:19 GMT

XSLT is a rule based language used to transform XML documents in to other file formats. XSLT are nothing but generic transformation rules which can be applied to transform XML document to HTML, CS, Rich text etc. the XSLT processor takes the XML file and applies the XSLT transformation to produce a different document.

XPATH It is an XML query language to select specific parts of an XML document. Using XPATH you can address or filter elements and text in a XML document. For instance a simple XPATH expression like "Invoice/Amount" states find "Amount" node which are children of "Invoice" node.

What is the main difference between MSML and .NET Framework XML classes?

Raj Shekhar — Fri, 22 Jan 2010 05:33:56 GMT

MSXML supports XMLDOM and SAX parsers while .NET framework XML classes support XML DOM and XML readers and writers.

MSXML supports asynchronous loading and validation while parsing. For instance you can send synchronous and asynchronous calls to a remote URL. But as such there is not direct support of synchronous and asynchronous calls in .NET framework XML. But same can be achieved by using "System.Net" namespaces.

Which are the namespaces in .NET used for XML?

Raj Shekhar — Fri, 22 Jan 2010 05:32:19 GMT

"System.xml.dll" is the actual physical file which has all XML implementation. Below are the commonly used namespaces:-

√ System.Xml

√ System.Xml.Schema

√ System.Xml.XPath

√ System.Xml.Xsl

What is XSL?

Raj Shekhar — Fri, 22 Jan 2010 05:30:50 GMT

XSL (the eXtensible Stylesheet Language) is used to transform XML document to some other document. So its transformation document which can convert XML to some other document. For instance you can apply XSL to XML and convert it to HTML document or probably CSV files.

What is CDATA and CSS section in XML?

Raj Shekhar — Fri, 22 Jan 2010 05:30:19 GMT

All data is normally parsed in XML but if you want to exclude some elements you will need to put those elements in CDATA.

With CSS you can format a XML document.

What is well formed XML & valid XML?

Raj Shekhar — Fri, 22 Jan 2010 05:29:16 GMT

If a XML document is confirming to XML rules (all tags started are closed, there is a root element etc) then it’s a well formed XML.

If XML is confirming to DTD rules then it’s a valid XML.

What is DTD (Document Type definition)?

Raj Shekhar — Fri, 22 Jan 2010 05:28:11 GMT

It defines how your XML should structure. For instance in the above XML we want to make it compulsory to provide "qty" and "totalcost", also that these two elements can only contain numeric. So you can define the DTD document and use that DTD document with in that XML

Can you explain why your project needed XML?

Raj Shekhar — Fri, 22 Jan 2010 05:24:34 GMT

Note: - This is an interview question where the interviewer wants to know why you have chosen XML. Remember XML was meant to exchange data between two entities as you can define your user friendly tags with ease. In real world scenarios XML is meant to exchange data. For instance you have two applications who want to exchange information. But because they work in two complete opposite technologies it’s difficult to do it technically. For instance one application is made in JAVA and the other in .NET. But both languages understand XML so one of the applications will spit XML file which will be consumed and parsed by other applications You can give a scenario of two applications which are working separately and how you chose XML as the data transport medium.

Is XML meant to replace HTML?

Raj Shekhar — Fri, 22 Jan 2010 05:23:55 GMT

No, they both go together one is for describing data while other is for displaying data.

What is the difference between XML and HTML?

Raj Shekhar — Fri, 22 Jan 2010 05:22:08 GMT

XML describes data while HTML describes how the data should be displayed. So HTML is about displaying information while XML is about describing information.

Is XML case sensitive?

Raj Shekhar — Fri, 22 Jan 2010 05:21:37 GMT

Yes, they are case sensitive.

If XML does not have closing tag will it work?

Raj Shekhar — Fri, 22 Jan 2010 05:21:13 GMT

No, every tag in XML which is opened should have a closing tag.

What is XML?

Raj Shekhar — Fri, 22 Jan 2010 05:20:13 GMT

XML (Extensible markup language) is all about describing data. Below is a XML which describes invoice data.

<? xml version="1.0" encoding="utf-8"?>
<Product>
   <productname>Shoes</productname>
   <qty>12</qty>
   <totalcost>100</totalcost>
   <discount>10</discount>
</Product>>

An XML tag is not something predefined but it is something you have to define according to your needs. For instance in the above example of invoice all tags are defined according to business needs. The XML document is self explanatory, any one can easily understand looking at the XML data what exactly it means.

What are the core functionalities in XML .NET framework? Can you explain in detail those functionalities?

Raj Shekhar — Fri, 01 Jan 2010 05:37:07 GMT

The XML API for the .NET Framework comprises the following set of functionalities:

XML readers: With XML readers the client application get reference to instance of reader class. Reader class allows you to scroll forward through the contents like moving from node to node or element to element. You can compare it with the "SqlDataReader" object in ADO.NET which is forward only. In short XML reader allows you to browse through the XML document.

XML writers Using XML writers you can store the XML contents to any other storage media. For instance you want to store the whole in memory XML to a physical file or any other media.

XML document classes XML documents provides a in memory representation for the data in an XMLDOM structure as defined by W3C. It also supports browsing and editing of the document. So it gives you a complete memory tree structure representation of your XML document.