com.twelvemonkeys.servlet

Class ThrottleFilter

java.lang.Object

com.twelvemonkeys.servlet.GenericFilter

com.twelvemonkeys.servlet.ThrottleFilter

All Implemented Interfaces:

Serializable, javax.servlet.Filter, javax.servlet.FilterConfig

public class ThrottleFilter
extends GenericFilter

ThrottleFilter, a filter for easing server during heavy load.

Intercepts requests, and returns HTTP response code 503 (Service Unavailable), if there are more than a given number of concurrent requests, to avoid large backlogs. The number of concurrent requests and the response messages sent to the user agent, is configurable from the web descriptor.

Version:

$Id: ThrottleFilter.java#1 $

Author:

Harald Kuhr, last modified by $Author: haku $

See Also:

setMaxConcurrentThreadCount(java.lang.String), setResponseMessages(java.lang.String), Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	DEFAULT_TYPE Default response content type
protected static String	DEFUALT_RESPONSE_MESSAGE Default response message sent to user agents, if the request is rejected
protected int	maxConcurrentThreadCount Minimum free thread count, defaults to 10

Fields inherited from class com.twelvemonkeys.servlet.GenericFilter

oncePerRequest

Constructor Summary

Constructors

Constructor and Description
ThrottleFilter()

Method Summary

Modifier and Type	Method and Description
protected void	doFilterImpl(javax.servlet.ServletRequest pRequest, javax.servlet.ServletResponse pResponse, javax.servlet.FilterChain pChain) Invoked once, or each time a request/response pair is passed through the chain, depending on the GenericFilter.oncePerRequest member variable.
void	setMaxConcurrentThreadCount(String pMaxConcurrentThreadCount) Sets the minimum free thread count.
void	setResponseMessages(String pResponseMessages) Sets the response message sent to the user agent, if the request is rejected.

Methods inherited from class com.twelvemonkeys.servlet.GenericFilter

destroy, doFilter, getFilterConfig, getFilterName, getInitParameter, getInitParameterNames, getServletContext, init, init, log, log, setFilterConfig, setOncePerRequest

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

maxConcurrentThreadCount

protected int maxConcurrentThreadCount

Minimum free thread count, defaults to 10

DEFUALT_RESPONSE_MESSAGE

protected static final String DEFUALT_RESPONSE_MESSAGE

Default response message sent to user agents, if the request is rejected

See Also:

Constant Field Values

DEFAULT_TYPE

protected static final String DEFAULT_TYPE

Default response content type

See Also:

Constant Field Values

Constructor Detail

ThrottleFilter

public ThrottleFilter()

Method Detail

setMaxConcurrentThreadCount

public void setMaxConcurrentThreadCount(String pMaxConcurrentThreadCount)

Sets the minimum free thread count.

Parameters:

pMaxConcurrentThreadCount -

setResponseMessages

public void setResponseMessages(String pResponseMessages)

Sets the response message sent to the user agent, if the request is rejected.
The format is <mime-type>=<filename>, <mime-type>=<filename>.
Example: <text/vnd.wap.wmlgt;=</errors/503.wml>, <text/html>=</errors/503.html>

Parameters:

pResponseMessages -

doFilterImpl

protected void doFilterImpl(javax.servlet.ServletRequest pRequest,
                            javax.servlet.ServletResponse pResponse,
                            javax.servlet.FilterChain pChain)
                     throws IOException,
                            javax.servlet.ServletException

Description copied from class: GenericFilter

Invoked once, or each time a request/response pair is passed through the chain, depending on the GenericFilter.oncePerRequest member variable.

Specified by:

doFilterImpl in class GenericFilter

Parameters:

pRequest -

pResponse -

pChain -

Throws:

IOException

javax.servlet.ServletException

See Also:

GenericFilter.oncePerRequest, doFilter, Filter.doFilter