Struts Interview Questions - Question Set 1

Thursday, September 23, 2010

Struts Interview Questions

1. What is Struts?
1.Struts is a web page development framework and an open source software that helps developers build web applications quickly and easily. Struts combines Java Servlets, Java Server Pages, custom tags, and message resources into a unified framework. It is a cooperative, synergistic platform, suitable for development teams, independent developers, and everyone between.

2.The core of the Struts framework is a flexible control layer based on standard technologies like Java Servlets, JavaBeans, ResourceBundles, and XML, as well as various Jakarta Commons packages. Struts encourages application architectures based on the Model 2 approach, a variation of the classic Model-View-Controller (MVC) design paradigm. Struts provides its own Controller component and integrates with other technologies to provide the Model and the View. For the Model, Struts can interact with standard data access technologies, like JDBC and EJB, as well as most any third-party packages, like Hibernate, iBATIS, or Object Relational Bridge. For the View, Struts works well with JavaServer Pages, including JSTL and JSF, as well as Velocity Templates, XSLT, and other presentation systems. The Struts framework provides the invisible underpinnings every professional web application needs to survive. Struts helps you create an extensible development environment for your application, based on published standards and proven design patterns.
3. Struts Frame work is the implementation of Model-View-Controller (MVC) design pattern for the JSP. Struts is maintained as a part of Apache Jakarta project and is open source. Struts Framework is suited for the application of any size. Latest version of struts can be downloaded from http://jakarta.apache.org/. We are using jakarta-struts-1.1 and jakarta-tomcat-5.0.4 for this tutorial.

2. How is the MVC design pattern used in Struts framework?
In the MVC design pattern, application flow is mediated by a central Controller. The Controller delegates requests to an appropriate handler. The handlers are tied to a Model, and each handler acts as an adapter between the request and the Model. The Model represents, or encapsulates, an application’s business logic or state. Control is usually then forwarded back through the Controller to the appropriate View. The forwarding can be determined by consulting a set of mappings, usually loaded from a database or configuration file. This provides a loose coupling between the View and Model, which can make an application significantly easier to create and maintain. Controller–Servlet controller which supplied by Struts itself; View — what you can see on the screen, a JSP page and presentation components; Model — System state and a business logic JavaBeans.

3. Who makes the Struts?
Struts is hosted by the Apache Software Foundation(ASF) as part of its Jakarta project, like Tomcat, Ant and Velocity.

4. Why it called Struts?
Because the designers want to remind us of the invisible underpinnings that hold up our houses, buildings, bridges, and ourselves when we are on stilts. This excellent description of Struts reflect the role the Struts plays in developing web applications.

5. Do we need to pay the Struts if being used in commercial purpose?
No. Struts is available for commercial use at no charge under the Apache Software License. You can also integrate the Struts components into your own framework just as if they were written in house without any red tape, fees, or other hassles.

6. What are the core classes of Struts?
Action, ActionForm, ActionServlet, ActionMapping, ActionForward are basic classes of Struts.

7. What is the design role played by Struts?
The role played by Struts is controller in Model/View/Controller(MVC) style. The View is played by JSP and Model is played by JDBC or generic data source classes. The Struts controller is a set of programmable components that allow developers to define exactly how the application interacts with the user.

8. What configuration files are used in Struts?
ApplicationResources.properties
struts-config.xml
These two files are used to bridge the gap between the Controller and the Model.

9. What helpers in the form of JSP pages are provided in Struts framework?
–struts-html.tld
–struts-bean.tld
–struts-logic.tld

10. Is Struts efficient?
The Struts is not only thread-safe but thread-dependent(instantiates each Action once and allows other requests to be threaded through the original object.
ActionForm beans minimize subclass code and shorten subclass hierarchies
The Struts tag libraries provide general-purpose functionality
The Struts components are reusable by the application
The Struts localization strategies reduce the need for redundant JSPs
The Struts is designed with an open architecture–subclass available
The Struts is lightweight (5 core packages, 5 tag libraries)
The Struts is open source and well documented (code to be examined easily)
The Struts is model neutral

11. How you will enable front-end validation based on the xml in validation.xml?
The < html:javascript > tag to allow front-end validation based on the xml in validation.xml. For example the code: < html:javascript formName=logonForm dynamicJavascript=true staticJavascript=true / > generates the client side java script for the form logonForm as defined in the validation.xml file. The < html:javascript > when added in the jsp file generates the client site validation script.

12. What is ActionServlet?
The class org.apache.struts.action.ActionServlet is the called the ActionServlet. In the the Jakarta Struts Framework this class plays the role of controller. All the requests to the server goes through the controller. Controller is responsible for handling all the requests.

13. How you will make available any Message Resources Definitions file to the Struts Framework Environment?
Message Resources Definitions file are simple .properties files and these files contains the messages that can be used in the struts project. Message Resources Definitions files can be added to the struts-config.xml file through < message-resources / > tag. Example: < message-resources parameter= MessageResources / >

14. What is Action Class?
The Action Class is part of the Model and is a wrapper around the business logic. The purpose of Action Class is to translate the HttpServletRequest to the business logic. To use the Action, we need to Subclass and overwrite the execute() method. In the Action Class all the database/business processing are done. It is advisable to perform all the database related stuffs in the Action Class. The ActionServlet (commad) passes the parameterized class to Action Form using the execute() method. The return type of the execute method is ActionForward which is used by the Struts Framework to forward the request to the file as per the value of the returned ActionForward object.

15. How Struts control data flow?
Struts implements the MVC/Layers pattern through the use of ActionForwards and ActionMappings to keep control-flow decisions out of presentation layer.

4 comments:

for IT the said...

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Ganesh Ponna said...

Hallo,


You make learning and reading addictive. All eyes fixed on you. Thank you being such a good and trust worthy guide.

totally new here (and quite new in the kingdom of ML) and this is my first question;

I am using XGBClassifier (latest version) in python training a dataset where the observations (should) have different weights. More specifically in am trying modelling the probability for an insurance policy to have a claim. The insurance policies may be on risk (have insurance cover) for different durations e.g. 1 month, 6 month 1 year creating the need to weight them according to how long they are on risk.

Is it possible to pass this (N*1) vectors which sums up to 1 to the XGBClassifier? If so, is the implication of this that obs. with weights are more likely to be picked by the sampling algo?

Hope somebody can enlighten me. Please let me know if I need to clarify something.

Thanks a lot. This was a perfect step-by-step guide. Don’t think it could have been done better.


Ciao,

Radhey Radhey said...

OlĂ ,


Grazie! Grazie! Grazie! Your blog is indeed quite interesting around
Freshers World - Freshers Jobs. I agree with you on lot of points!


how to get the first non space character from a string in Oracle. Could you help me on this?



Anyways great write up, your efforts are much appreciated.

Many Thanks,
Radhey

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