atg.droplet
Class Cache

java.lang.Object
  atg.nucleus.logging.VariableArgumentApplicationLoggingImpl
      atg.nucleus.GenericService
          atg.nucleus.TimedOperationService
              atg.nucleus.servlet.ServletService
                  atg.nucleus.servlet.HttpServletService
                      atg.servlet.DynamoServlet
                          atg.droplet.Cache

All Implemented Interfaces:

MessageSink, NameContextBindingListener, NameContextElement, NameResolver, AdminableService, ApplicationLogging, atg.nucleus.logging.ApplicationLoggingSender, atg.nucleus.logging.TraceApplicationLogging, VariableArgumentApplicationLogging, ComponentNameResolver, Service, ServiceListener, ParameterServlet, java.util.EventListener, javax.servlet.Servlet

public class Cache
extends DynamoServlet
implements MessageSink

This droplet caches the contents of its oparam named output. It improves performance for pages that generate dynamic content which is the same for all users, or where there are a small number of versions of the content (for example, one version for members and another for guests).

If your request is rewriting URLs to include the session id, the session id and request id will be removed from the cached content. This prevents session ids from being returned to incorrect users. If you know that the contents of your oparam do not define any URLs and you want to improve the performance of this case by avoiding the search for session ids, you can specify the parameter hasNoURLs to "true".

Your cached content will periodically be regenerated the first request after a specified time interval has elapsed since the content was cached. You can specify what this interval should be with the request parameter cacheCheckSeconds. If no cacheCheckSeconds parameter is supplied, the content is expired using the bean property defaultCacheCheckSeconds on the cache droplet itself.

It is possible to have more than one view of the cached data associated with each cache droplet invocation. For example, if your page had different views for members and non-members, you can still use the cache droplet. To do this, set the key request parameter to contain the a value that uniquely identifies the content of the page. In the above example, we'd set the key parameter to "true" for members and "false" for non-members. The cache droplet maintains separate cached content for each value of the key parameter. You do not need to supply system wide unique key values. Each cache droplet gets its own name space of key values.

All content managed by a single cache droplet instance is periodically purged based on the property purgeCacheSeconds (the default is every 6 hours). This is to retrieve data storage for instances of the cache droplet that are no longer in use. This would happen if you remove or recompile a jhtml page that has a cache droplet.

If you visit the admin page for this component in the component browser, you can see statistics about the content which is cached.

The Cache component itself is a JMS message sink. When it receives a message, it flushes any content that it may define. You can use multiple instance of the Cache servlet bean if you would like to control which content gets flushed for a JMS message.

Field Summary

static java.lang.String	CLASS_VERSION
static java.lang.String	DO_NOT_CACHE_RESPONSE
static java.lang.String	PROTOCOL_CHANGE_DROPLET

Fields inherited from class atg.servlet.DynamoServlet

mAllowCleanupRequest, mParameters

Fields inherited from class atg.nucleus.servlet.ServletService

SERVLET_INFO_KEY

Fields inherited from class atg.nucleus.GenericService

SERVICE_INFO_KEY

Fields inherited from interface atg.nucleus.logging.TraceApplicationLogging

DEFAULT_LOG_TRACE_STATUS

Fields inherited from interface atg.nucleus.logging.ApplicationLogging

DEFAULT_LOG_DEBUG_STATUS, DEFAULT_LOG_ERROR_STATUS, DEFAULT_LOG_INFO_STATUS, DEFAULT_LOG_WARNING_STATUS

Constructor Summary

Cache()

Method Summary

protected javax.servlet.Servlet	createAdminServlet() Creates and returns a new Servlet that will administer this service.
java.lang.String	ensureNoIds(DynamoHttpServletRequest pRequest, java.lang.String cacheData)
void	flushCache() Forces cache to flush the data.
char[]	getCachedContent(DynamoHttpServletRequest pRequest) Returns the cached content for the given request.
int	getDefaultCacheCheckSeconds()
boolean	getEnabled()
atg.servlet.pagecompile.PageEncodingTyper	getEncodingTyper()
long	getPurgeCacheSeconds()
java.lang.String	getSessionURLName() The name for the session id.
void	init(javax.servlet.ServletConfig pConfig) Initializes the servlet.
boolean	isCachingEnabled(DynamoHttpServletRequest pRequest) If this returns false, then the droplet should proceed as if no caching is involved at all.
void	receiveMessage(java.lang.String pPortName, javax.jms.Message pMessage) Called by DMS when a Message arrives through the given input port.
void	removeCachedElement(java.lang.String key)
void	service(DynamoHttpServletRequest pRequest, DynamoHttpServletResponse pResponse) Determine whether we have a valid cached entry.
void	setCachedContent(DynamoHttpServletRequest pRequest, char[] pContent) Sets the cached content for the given request.
void	setDefaultCacheCheckSeconds(int pCheckCacheSeconds) This property specifies the default time interval for invalidating cached content if the droplet does not receive the request parameter cacheCheckSeconds.
void	setEnabled(boolean pEnabled) Sets the property Enabled.
void	setEncodingTyper(atg.servlet.pagecompile.PageEncodingTyper pEncodingTyper) Sets the property EncodingTyper.
void	setPurgeCacheSeconds(long pPurgeCacheSeconds) This property specifies the default time interval for purging the entire collection of cached content.
void	setSessionURLName(java.lang.String pSessionURLName) The name for the session id.

Methods inherited from class atg.servlet.DynamoServlet

doDelete, doGet, doPost, doPut, getParameter, getParameters, getServletContext, service, service, setParameter

Methods inherited from class atg.nucleus.servlet.ServletService

destroy, getServletConfig, getServletInfo, setServletInfo

Methods inherited from class atg.nucleus.TimedOperationService

getAverageRequestHandlingTime, getHandledRequestCount, getRequestStartTime, getTotalRequestHandlingTime, isKeepingStatistics, notifyHandledRequest, resetStatistics, setKeepingStatistics

Methods inherited from class atg.nucleus.GenericService

addLogListener, doStartService, doStopService, getAbsoluteName, getAdminServlet, getLoggingForVlogging, getLogListenerCount, getLogListeners, getName, getNameContext, getNucleus, getRoot, getServiceConfiguration, getServiceInfo, isLoggingDebug, isLoggingError, isLoggingInfo, isLoggingTrace, isLoggingWarning, isRunning, logDebug, logDebug, logDebug, logError, logError, logError, logInfo, logInfo, logInfo, logTrace, logTrace, logTrace, logWarning, logWarning, logWarning, nameContextElementBound, nameContextElementUnbound, removeLogListener, resolveName, resolveName, resolveName, resolveName, sendLogEvent, setLoggingDebug, setLoggingError, setLoggingInfo, setLoggingTrace, setLoggingWarning, setNucleus, setServiceInfo, startService, stopService

Methods inherited from class atg.nucleus.logging.VariableArgumentApplicationLoggingImpl

vlogDebug, vlogDebug, vlogDebug, vlogDebug, vlogError, vlogError, vlogError, vlogError, vlogInfo, vlogInfo, vlogInfo, vlogInfo, vlogTrace, vlogTrace, vlogTrace, vlogTrace, vlogWarning, vlogWarning, vlogWarning, vlogWarning

Methods inherited from class java.lang.Object

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

Field Detail

CLASS_VERSION

public static java.lang.String CLASS_VERSION

DO_NOT_CACHE_RESPONSE

public static final java.lang.String DO_NOT_CACHE_RESPONSE

See Also:

Constant Field Values

PROTOCOL_CHANGE_DROPLET

public static final java.lang.String PROTOCOL_CHANGE_DROPLET

See Also:

Constant Field Values

Constructor Detail

Cache

public Cache()

Method Detail

setSessionURLName

public void setSessionURLName(java.lang.String pSessionURLName)

The name for the session id. Usually "jsessionid".

getSessionURLName

public java.lang.String getSessionURLName()

The name for the session id. Usually "jsessionid".

service

public void service(DynamoHttpServletRequest pRequest,
                    DynamoHttpServletResponse pResponse)
             throws javax.servlet.ServletException,
                    java.io.IOException

Determine whether we have a valid cached entry. If so, render from the cache, otherwise, render the output parameter, caching the results for rendering the next time.

Overrides:

service in class DynamoServlet

Parameters:

pRequest - the request to be processed

pResponse - the response object for this request

Throws:

javax.servlet.ServletException - an application specific error occurred processing this request

java.io.IOException - an error occurred reading data from the request or writing data to the response.

ensureNoIds

public java.lang.String ensureNoIds(DynamoHttpServletRequest pRequest,
                                    java.lang.String cacheData)

removeCachedElement

public void removeCachedElement(java.lang.String key)

setDefaultCacheCheckSeconds

public void setDefaultCacheCheckSeconds(int pCheckCacheSeconds)

This property specifies the default time interval for invalidating cached content if the droplet does not receive the request parameter cacheCheckSeconds.

getDefaultCacheCheckSeconds

public int getDefaultCacheCheckSeconds()

setPurgeCacheSeconds

public void setPurgeCacheSeconds(long pPurgeCacheSeconds)

This property specifies the default time interval for purging the entire collection of cached content. This is necessary to free up content associated with pages that are no longer in use by the system (i.e. jhtml pages that have been recompiled).

getPurgeCacheSeconds

public long getPurgeCacheSeconds()

setEnabled

public void setEnabled(boolean pEnabled)

Sets the property Enabled. If the servlet is not enabled, the output parameter is sent to the browser without any caching.

getEnabled

public boolean getEnabled()

Returns:

The value of the property Enabled.

flushCache

public void flushCache()

Forces cache to flush the data.

receiveMessage

public void receiveMessage(java.lang.String pPortName,
                           javax.jms.Message pMessage)
                    throws javax.jms.JMSException

Called by DMS when a Message arrives through the given input port. There may be concurrent calls of this method from multiple Threads.

Specified by:

receiveMessage in interface MessageSink

Throws:

javax.jms.JMSException - if there is a problem processing the message

setEncodingTyper

public void setEncodingTyper(atg.servlet.pagecompile.PageEncodingTyper pEncodingTyper)

Sets the property EncodingTyper.

getEncodingTyper

public atg.servlet.pagecompile.PageEncodingTyper getEncodingTyper()

Returns:

The value of the property EncodingTyper.

createAdminServlet

protected javax.servlet.Servlet createAdminServlet()

Creates and returns a new Servlet that will administer this service.

Overrides:

createAdminServlet in class GenericService

isCachingEnabled

public boolean isCachingEnabled(DynamoHttpServletRequest pRequest)

If this returns false, then the droplet should proceed as if no caching is involved at all. This would be false if the enabled property is set to false, or if session tracking is enabled and URL rewriting is happening (and hasNoURLs is not set in the request).

getCachedContent

public char[] getCachedContent(DynamoHttpServletRequest pRequest)

Returns the cached content for the given request. The key for the content is a combination of the request URI and the "key" parameter - the "key" parameter must be specified. The optional "cacheCheckSeconds" parameter indicates how long the content should remain in the cache.

setCachedContent

public void setCachedContent(DynamoHttpServletRequest pRequest,
                             char[] pContent)

Sets the cached content for the given request. The key for the content is a combination of the request URI and the "key" parameter, which must be specified.

init

public void init(javax.servlet.ServletConfig pConfig)
          throws javax.servlet.ServletException

Initializes the servlet. This is called automatically by the system when the servlet is first loaded.

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class ServletService

Parameters:

pServletConfig - servlet configuration information

Throws:

javax.servlet.ServletException - if a servlet exception has occurred