Re: Request Interceptor

Thu, 25 Apr 2002 12:08:58 -0700 

hi subir,

Thanks for the solution,
I got the code working.


I was using request.getFacade() to get an instance of httpServletRequest

Thanks,
Venky

  ----- Original Message ----- 
  From: Subir Sengupta 
  To: 'Tomcat Users List' 
  Sent: Thursday, April 25, 2002 11:02 AM
  Subject: RE: Request Interceptor


  Here's an example of a filter.  This will run (after you put in the correct
  package) as is.  It doesn't do anything terribly useful, but it should show
  you how a filter works.

  package xx.xx.xx;

  import java.io.*;
  import javax.servlet.*;
  import javax.servlet.http.*;

  public class ExampleFilter implements Filter {

    private FilterConfig config = null;

    public void init(FilterConfig config) throws ServletException {
      this.config = config;
    }

    public void destroy() {
      config = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                       FilterChain chain) throws IOException, ServletException
  {
      System.out.println("Increment your counter here");
      chain.doFilter(request, response);
      System.out.println("Decrement your counter here");
    }
  }

  In your web.xml add these statements.  Put them before any servlet elements.

  <filter>
      <filter-name>ExampleFilter</filter-name>
      <filter-class>xx.xx.xx.ExampleFilter</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>ExampleFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>

  BTW, what does request.getFacade() do?  I'm converting some Tomcat 3.x code
  to T4 and it looks like that method doesn't exist in T4.  Since I didn't
  write the T3 code in not sure how to replace it.

  Subir

  -----Original Message-----
  From: Venkatesh Sangam [mailto:[EMAIL PROTECTED]]
  Sent: Wednesday, April 24, 2002 6:03 PM
  To: [EMAIL PROTECTED]
  Subject: RE: Request Interceptor


  Hi Subir,

  I had the following interceptor class for Tomcat 3.2.2

  public class CountRequest extends BaseInterceptor
  {


  static int noOfRequests=0;
      public CountRequest()
      {
          super();
      }


     public int preService(Request request, Response response) {
     try{
    HttpServletRequest req =request.getFacade();

  if
  (request.getServletPath().equalsIgnoreCase("/servlet/Read")){
  noOfRequests++;
  System.out.println("/servlet/Read
  "+noOfRequests);

  }

  if
  (request.getServletPath().equalsIgnoreCase("/servlet/LoadTest")) {
  Integer load = new Integer(noOfRequests);
  req.setAttribute("load",load.toString());
  System.out.println("/servlet/LoadTest
  ="+noOfRequests);
  }
     } catch (Exception e){System.out.println("Exception is
  Performance
  Interceptor");}
     return 0;
  }


      /*postService is invoked right after service() is invoked on the actual
  servlet*/
      public int postService(Request request, Response response) {

  if
  (request.getServletPath().equalsIgnoreCase("/examples/servlet/Read"))
  noOfRequests--;
  return 0;
      }


  }



  I used to increment noOfRequests in preService and decrement it in
  postService. But, How do I do the same in Tomcat 4.0

  Thanks
  Venky












  ----Original Message Follows----
  From: Subir Sengupta <[EMAIL PROTECTED]>
  Reply-To: "Tomcat Users List" <[EMAIL PROTECTED]>
  To: 'Tomcat Users List' <[EMAIL PROTECTED]>
  Subject: RE: Request Interceptor
  Date: Wed, 24 Apr 2002 17:53:42 -0700

  T4 doesn't have interceptors.  It sounds like you can do what you need to do
  with a filter.

  Hope that helps,
  Subir

  -----Original Message-----
  From: Venkatesh Sangam [mailto:[EMAIL PROTECTED]]
  Sent: Wednesday, April 24, 2002 5:03 PM
  To: [EMAIL PROTECTED]
  Subject: Request Interceptor


  Hi,
  can any body please tell me where do put my request iterceptor in Tomcat 4
  I could easily do this using Tomcat 3.2.2 in server.xml file.

  I need to intercept request to measure the load in the tomcat server. ie I
  need to count the number of requests at any point in time..

  I already have written the progrom and the interceptor is working fine with
  Tomcat 3.2.2.
  But Can any body please tell me how do I do the same using Tomcat 4.0.3

  <RequestInterceptor class="CountRequests" />


  Thanks
  Venky


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