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Article:
  Clustering and Load Balancing in Tomcat 5, Part 2
Subject:   Not able to locate BalancerFilter
Date:   2005-07-20 02:02:00
From:   IDunno
Response to: Not able to locate BalancerFilter

You can see BalancerFilter in Tomcat sources :



<sourcedir>/jakarta-tomcat-catalina/webapps/balancer/WEB-INF/classes/org/apache/webapp/balancer/BalancerFilter.java


Here is the source :




/*
* Copyright 2000,2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.webapp.balancer;


import java.io.IOException;
import java.io.InputStream;


import java.net.URL;


import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;



/**
* The balancer filter redirects incoming requests
* based on what rules they match. The rules
* are configurable via an XML document whose URL
* is specified as an init-param to this filter.
*
* @author Yoav Shapira
*/
public class BalancerFilter implements Filter {
/**
* The rules this filter consults.
*/
private RuleChain ruleChain;


/**
* The servlet context.
*/
private ServletContext context;


/**
* Returns the rule chain.
*
* @return The rule chain
*/
protected RuleChain getRuleChain() {
return ruleChain;
}


/**
* Initialize this filter.
*
* @param filterConfig The filter config
* @throws ServletException If an error occurs
*/
public void init(FilterConfig filterConfig) throws ServletException {
context = filterConfig.getServletContext();


String configUrlParam = filterConfig.getInitParameter("configUrl");


if (configUrlParam == null) {
throw new ServletException("configUrl is required.");
}


try {
InputStream input = context.getResourceAsStream(configUrlParam);
RulesParser parser = new RulesParser(input);
ruleChain = parser.getResult();
context.log(
getClass().getName() + ": init(): ruleChain: " + ruleChain);
} catch (Exception e) {
throw new ServletException(e);
}
}


/**
* Filter the incoming request.
* Consults the rule chain to see if
* any rules match this request, and if
* so redirects. Otherwise simply
* let request through.
*
* @param request The request
* @param response The response
* @param chain The filter chain
* @throws IOException If an error occurs
* @throws ServletException If an error occurs
*/
public void doFilter(
ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
if (response.isCommitted()) {
context.log(
getClass().getName()
+ ": doFilter(): not inspecting committed response.");
chain.doFilter(request, response);
} else if (!(request instanceof HttpServletRequest)) {
context.log(
getClass().getName()
+ ": doFilter(): not inspecting non-Http request.");
chain.doFilter(request, response);
} else {
HttpServletRequest hreq = (HttpServletRequest) request;
HttpServletResponse hres = (HttpServletResponse) response;


URL redirectUrl = getRuleChain().evaluate(hreq);


if (redirectUrl != null) {
String encoded =
hres.encodeRedirectURL(redirectUrl.toString());


context.log(
getClass().getName()
+ ": doFilter(): redirecting request for "
+ hreq.getRequestURL().toString() + " to " + encoded);


hres.sendRedirect(encoded);
} else {
chain.doFilter(request, response);
}
}
}


/**
* Destroy this filter.
*/
public void destroy() {
context = null;
ruleChain = null;
}
}



// End of file: BalanceFilter.java


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  1. Not able to locate BalancerFilter
    2005-12-19 20:59:27  minil [View]

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