Saturday 16 June 2012

WEBLOGIC SERVER FAQ(ANS)--1

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weblogic interview questions and answers

1.What is application server?
  • An application server is a software framework dedicated to the efficient execution of procedures (scripts, routines, programs ...) for supporting the construction of applications. The term was created in the context of web applications. In these, the application server acts as a set of components accessible to the software developer through an API defined by the platform itself. These components are usually performed in the same machine where the web server is running, and their main job is to support the construction of dynamic pages.
  • Other uses of the term can refer to:
    • the services that a server makes available
    • the computer hardware on which the services run
  • Java application servers
  • Following the success of the Java platform, the term application server sometimes refers to a J2EE or Java EE 5 application server. Some of the better-known Java Enterprise Edition application servers include:
    • Apache Tomcat (Apache Software Foundation)
    • Tcat Server (MuleSoft)
    • WebSphere Application Server and WebSphere Application Server Community Edition (IBM)
    • Sybase Enterprise Application Server (Sybase Inc)
    • WebLogic Server (Oracle)
    • JBoss (Red Hat)
    • Apache Geronimo (Apache Software Foundation)
    • Oracle OC4J (Oracle)
    • SAP Netweaver AS (ABAP/Java) (SAP)
    • WebObjects (Apple Inc.)
  • The web modules include servlets and JavaServer Pages. Business logic resides in Enterprise JavaBeans (EJB-3 and later). The Hibernate project offers an EJB-3 container implementation for the JBoss application server. Tomcat from Apache and JOnAS from ObjectWeb exemplify typical containers which can store these modules.
  • A Java Server Page (JSP) (a servlet from Java) executes in a web container — the Java equivalent of CGI scripts. JSPs provide a way to create HTML pages by embedding references to the server logic within the page. HTML coders and Java programmers can work side by side by referencing each other's code from within their own. JavaBeans are the independent class components of the Java architecture from Sun Microsystems.
2.What is web server?
  • The primary function of a web server is to deliver web pages (HTML documents) and associated content (e.g. images, style sheets, JavaScript's) to clients. A client, commonly a web browser or web crawler, makes a request for a specific resource using HTTP and, if all goes well, the server responds with the content of that resource. The resource is typically a real file on the server's secondary memory, but this is not necessarily the case and depends on how the web server is implemented.
  • While the primary function is to serve content, a full implementation of HTTP also includes a way of receiving content from clients. This feature is used for submitting web forms, including uploading of files.
  • Many generic web servers also support server-side scripting (e.g. Apache HTTP Server and PHP). This means that the behavior of the web server can be scripted in separate files, while the actual server software remains unchanged. Usually, this functionality is used to create HTML documents on-the-fly as opposed to return fixed documents. This is referred to as dynamic and static content respectively.
  • History of web servers
  • In 1989 Tim Berners-Lee proposed to his employer CERN (European Organization for Nuclear Research) a new project, which had the goal of easing the exchange of information between scientists by using a hypertext system. As a result of the implementation of this project, in 1990 Berners-Lee wrote two programs:
    • a browser called Worldwide Web;
    • the world's first web server, later known as CERN httpd, which ran on NeXTSTEP.
  • Between 1991 and 1994 the simplicity and effectiveness of early technologies used to surf and exchange data through the World Wide Web helped to port them to many different operating systems and spread their use among lots of different social groups of people, first in scientific organizations, then in universities and finally in industry.
  • In 1994 Tim Berners-Lee decided to constitute the World Wide Web Consortium to regulate the further development of the many technologies involved (HTTP, HTML, etc.) through a standardization process.
  • Common features
    • Virtual hosting to serve many web sites using one IP address.
    • Large file support to be able to serve files whose size is greater than 2 GB on 32 bit OS.
    • Bandwidth throttling to limit the speed of responses in order to not saturate the network and to be able to serve more clients.
3.What is the difference between Web server and Application Server?

 Application Server
  •  Webserver serves pages for viewing in web browser, application server provides exposes business logic for client applications through various protocols
  •  Webserver exclusively handles http requests. Application server serves business logic to application programs through any number of protocols.
  •  Webserver delegation model is fairly simple, when the request comes into the webserver, it simply passes the request to the program best able to handle it(Server side program). It may not support transactions and database connection pooling.
  •  Application server is more capable of dynamic behavior than webserver. We can also configure application server to work as a webserver. Simply application server is a superset of webserver.
WEB Server
  • Web Server serves static HTML pages or gifs, jpegs, etc., and can also run code written in CGI, JSP etc. A Web server handles the HTTP protocol. Eg of some web server are IIS or apache.
  • An Application Server is used to run business logic or dynamically generated presentation code. It can either be .NET based or J2EE based (BEA WebLogic Server, IBM WebSphere, JBoss).
  • A J2EE application server runs servlets and JSPs (infact a part of the app server called web container is responsible for running servlets and JSPs) that are used to create HTML pages dynamically. In addition, J2EE application server can run EJBs - which are used to execute business logic.
  • An Application server has a 'built-in' web server; in addition to that it supports other modules or features like e-business integration, independent management and security module, portlets etc.
4.What is the Domain in Weblogic serve?
    • Domain is a logically related group of Oracle WebLogic Server resources that are managed as a single unit
    • Domain Provides one point of administration
    • Can logically separate:
      • Development, test, and production applications
      • Organizational divisions
5.What are the Domain Restrictions?
    • Each domain requires its own Administration Server.
    • A cluster cannot span multiple domains.
    • The Managed Servers in a domain must run the same version of Oracle WebLogic Server.
    • The Administration Server in a domain must run the same or higher version as Managed Servers in the domain.
6.What is the server?
    • A server is an instance of weblogic.Server executing in a Java Virtual Machine (JVM).
    • A server:
      • Runs on a designated Oracle WebLogic Server machine
      • Has a dedicated amount of RAM
      • Is multithreaded
    • Two types of servers:
      • Administration Server
      • Managed Server

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