10 XSLT or XML, XSL transformation Interview Questions and Answers for Java Programmers

XSLT stands for XML style sheet
transformation and it as XML technology used to transform one XML into
another XML or HTML format.  XML and XSLT interview questions are
commonly asked to Java developers, who happen to use XML in there project and
mentioned XSLT as key skill in there resume. Given XML’s popularity
as data transfer protocol, many systems in middle and back office space uses XML messages to transfer trade
details, for example Bookings, Settlement, and Confirmation system uses it as a
data exchange protocol. Since each of this system performs some normalization,
enrichment and transform on incoming trade message, they use XSLT for those
transformation. XSLT is rich, powerful and given it’s support in
Java and several other programming language, it comes natural choice of XML
transformation. What you need to is to write XSL files,
also known as XML style sheet to specify your transformation
rule and than XSLT engine will transform each incoming XML documents
as per your XSL file. Though, XSLT is rich, it’s can also be
very complex for Java programmers, who are used to procedural style of coding,
as XSLT uses recursion a lot. So if you are
a Java programmer, who have used XSLT or going
for a Job interview, where XSLT is a key skill, you better be prepare with some
popular XSLT interview questions, In this article, I am
sharing my list of XSLT questions, which is collected from internet,
friends and colleagues and frequently asked as part of XML Interview questions.

XSLT or XML transformation Interview
Questions Answers

Here is my list of XSLT questions, which is frequently asked to Java
developers for projects, who uses XML extensively for transferring data,
generating dynamic HTML and other XML
transformation task. Though these XSLT interview
question are not very difficult, but they can be tricky, given XSLT not being
Java programmers main strength and lack of time on learning XSLT. You can
use these questions for preparation or refreshing your knowledge before going
for any Java and XML based Job
interview.

Question
1: What is XSL transformation or XSLT? How do you perform XML transformation in
Java?

Answer : XSL transformation is the process of transforming one XML file
into another XML, HTML or other
type of file based upon selective rules and condition. XSL(XML Style Sheet
language) is used to define those rules and condition in a .xls file, which is called style sheet document. Any XSLT engine can
read those instruction defined in style sheet document and transform source XML
file into something expected. Core of XSLT is, transformation
engine and style sheet  document. XSLT engine can
be written in Java or any other language. Java has XSLT support via javax.xml.transform package
which specifies classes like Templates, TransformFactory, an implementation of abstract factory design pattern,  which can
be used to read XSL file and transform XML files. See XSL transformation in
Java for more details

Question
2: How to remove a particular element from XML?

Answer : Removing element from XML document via XSL transformation or
XSLT is easy if you are familiar with Identity template. You need to write two
templates one is Identity template, which copies every thing and other for
matching with particular element and doing nothing just like shown below, which
will then result in removal of a that particular element. See an example of
removing XML elements using XSLT for details.

Question
3: How to remove a particular attribute from XML?

Answer : Process of removing an attribute
is similar to removing elements from XML
document, as discussed in above XSLT interview
question. Along with Identity template, define another template to match
with that particular attribute as shown below.

match="@product_synonym"/>

Question
4: How to rename a particular element and attribute from XML using XSL?

Answer : Renaming attribute is also similar to removing or deleting
attribute as discussed in XSLT question 1, but instead of not doing anything
when an attribute matches, you need to create an attribute and copy value of
current attribute into new attribute. Identity template will be same and you
need to add another template for renaming attribute using XSL:

    name="emp_id">

         select="." />

   

if you are using XSLT 2.0 than instead of separate
element you can use select attribute directly with
as shown below

select=".">

Question
5: What is Identity template in XSL,  why
do you use it?

Answer : Identity template in XSL is used to create deep copy of source XML file. It's template
matches to every node() and attribute and copy everything
to create copy of original xml file. many people define Identity template in its
own file like Identity.xsl but some people also preferred to
keep in main XSL file as top template. Identity template has several uses in
XSL transformation, like if you want to remove any attribute or element you
will most likely copy everything using Identity template and create another
template for not doing anything for those attribute or elements as discussed in
XSLT interview questions 1 and 2.

  

       select="@|node()"/>

  

Above template is called Identity template. If you look at definition
first template matches any attribute or

any node and then copies current node including any attributes and child
nodes.

Question
6 : Why we use select="@|node()" in the
element on Identity template? what will happen if we use
without select attribute?

Answer : This is an extension or follow up questions of previous XSLT question about Identity template. we use select="@|node() to copy
all child element and any attribute.if we don't use that than will
default on select="node()" which will
copy child nodes except attributes.

Question
7:  Can you explain me this XSL template?
What output this XSL template will produce given a particular xml file?

Answer : This kind of XSL transformation questions are more popular to
gauge real understanding of templates. they can write template in front of you and may ask you to explain, most simple
example of this is writing Identity template as discussed in
XSLT interview question 3. Alternatively they may give you XSL and XML file and
ask you about about of transformation. This are tricky questions in XSL and in
order to answer these question you need to be familiar with XSL language, which
is the primary reason people ask it. On the other hand this is an excellent
opportunity to show you how well you know about XSL working or how template executes,
by clearly explaining what a particular template does.

Question
8 : How to retrieve value of an attribute for an element using XSLT?

Answer : This XSLT interview question is pretty common in many XML
interviews as well. If candidate has worked in XSLT then this is a fairly easy
question as it just need to come up with a XSLT template which can copy an
attribute from an element like below:

match="/employees/employee">

Value of attribute Id is :

select="@id">

Question
9 : How do you generate dynamic HTML pages from relational database using XSLT?

Answer : This is one of the XSLT interview questions which checks
practical knowledge of candidate in XSL. This is one of the most common
application of XSLT I have seen where data stored in relational database is
converted into XML and by using XSLT transformed into HTML pages. Database stored procedure can
be used for first part and having all the logic of rendering HTML in XSLT you
don't need to change your query now and then if you need to change structure of
HTML pages. If candidate successfully answer this XSLT interview question then
there is very good chance that he has a good understanding of how things works
with database, xml and XSLT.

Now let’s see couple of XSLT Interview question for practice, you need to
find answer of these two questions by yourself, and once you find the answer,
you can also post them as comment here. The reason, I am not giving answer of
these question here because, they are extremely basic and should come as
experience, i.e. you would better write code for that. That will enable you to
understand other XSLT questions as well.

How to
transform one XML to another XML document using XSLT transform?

How to
transform an XML file into HTML using XSL transformation (XSLT)?

That’s all on my list of XSLT and XML transformation interview
questions and answers. XSLT is one of the important skill to have in your
resume, if you are using XML in your project. Since XML is mostly used as
transportation protocol and middle and back office systems, those roles look
for candidates which are good in XML, XSL and XSLT transformation. So if you
are applying for any middle and back office Java development role in Investment
banks, make sure to prepare XSLT well.

Source:http://javarevisited.blogspot.com/2013/05/10-xslt-or-xml-xsl-transformation-interview-questions-answers-java.html