Interview Questions and Answers

• Tomcat is a Java Servlet container and web server from the Jakarta project of the Apache software foundation.
• A web server responds with web pages to requests from client browsers.
• Web servers can provide dynamic content based on the requests sent by the user.
• Tomcat is very good to provide dynamic content because it provides both Java servlet and JavaServerPages (JSP) technologies.
• Tomcat can also be used as a web server for many applications even if free servlet and JSP engine is wanted.
• It can be used standalone or used behind traditional web servers such as Apache httpd, with the traditional server serving static pages and Tomcat serving dynamic servlet and JSP requests.

• Use a ResourceBundle. See the Java docs for the specifics of how the ResourceBundle class works. Using this method, the properties file must go into the WEB-INF/classes directory or in a jar file contained in the WEB-INF/lib directory. 
  
• Another way is to use the method getResourceAsStream() from the ServletContext class. This allows you update the file without having to reload the webapp as required by the first method. Here is an example code snippet, without any error trapping: 

// Assuming you are in a Servlet extending HttpServlet
// This will look for a file called "/more/cowbell.properties" relative
// to your servlet Root Context
InputStream is = getServletContext().getResourceAsStream("/more/cowbell.properties");
Properties p = new Properties();
p.load(is);
is.close();

• Create ${catalina.home}/www/appBase , ${catalina.home}/www/deploy, and ${catalina.home}/conf/Catalina/www.myhostname.com
  
• Add a host entry in the server.xml file 
  
• Create the the following file under conf/Catalina/www.myhostname.com/ROOT.xml 
  
• Add any parameters specific to this hosts webapp to this context file 
  
• Put your war file in ${catalina.home}/www/deploy 
  
• When tomcat starts, it finds the host entry, then looks for any context files and will start any apps with a context.

• Configure IIS to use "integrated windows security"
  
• In server.xml, make sure you disable tomcat authentication: 
  

<Connector port="8009" enableLookups="false" redirectPort="8443" protocol="AJP/1.3" tomcatAuthentication="false" />

Principal p = request.getUserPrincipal(); 

String emailAddress = p.getClass().getMethod("getEmailAddress", null).invoke(p, null);

You could put your custom classes in a classloader that is common to both the server and your webapp - e.g., either the "common" or bootstrap classloaders. To do this, however, you would also need to move the classes that your custom classes depend on up to the common classloader, and that seems like a bad idea, because there a many of them and they a core server classes. 

Rather than move the implementing custom classes up, you could define interfaces for your customs classes, and put the interfaces in the common directory. You're code would look like this: 

public interface MyPrincipalInterface extends java.security.Principal { 

public String getEmailAddress();

}

public class MyPrincipal implements MyPrincipalInterface { 

...

public String getEmailAddress() {

return emailAddress;

}

}

public class MyServlet implements Servlet { 

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws

ServletException, IOException {

MyPrincipalInterface p = (MyPrincipalInterface)request.getUserPrincipal();

String emailAddress = p.getEmailAddress();

...

}

Notice that this method gives you pretty much the webapp code you wanted in the first place

You might want to try serializing the response of 'request.getUserPrincipal()' and deserialize it to an instance of [webapp]MyPrincipal.