org.qbroker.monitor

Class URLMonitor

java.lang.Object

org.qbroker.monitor.Monitor

org.qbroker.monitor.URLMonitor

All Implemented Interfaces:

MonitorAction, MonitorReport

public class URLMonitor
extends Monitor

URLMonitor monitors a given web page on its last modified time and/or size

Use URLMonitor to get the update time and/or size of the given page. It is assumed that the page exists and is accessible all times. The page should contain update time stamp that will be parsed by URLMonitor.

You can use URLMonitor to monitor when the page has been updated. If not, how late it is. In case of very late, URLMonitor sends alerts.

URLMonitor also supports mtime correlations and size correlations between the page and other mtime objects. In this case, there are two objects involved. One is the reference. The other is the target page to be monitored. The reference controls the correlation process. Whenever the reference is updated or modified, URLMonitor adjusts its timer and correlates this change with the target page. If the target page has been updated accordingly, the URLMonitor treats it OK. Otherwise, it will send alerts according to the predefined tolerance on the lateness of the target page being updated.

In order to configure URLMonitor to do time correlations, you have to specify a map named reference in its property map. The reference map contains most of the properties required by an mtime object, such as uri, name, type, etc. The tolerance of the lateness will be controlled by the threshold parameters. In fact, URLMonitor will create a separate instance for the reference. The method of performAction() will actually do the time correlations between two objects.

In case of the size correlations, you must specify the triggerSize in the property map. The triggerSize is zero or any positive number that defines two different states. One is the state that the page size is less than the trigger_size. The other is the opposite. In case state of the reference changes, URLMonitor will check the state of the target page. If both are in the same states, URLMonitor thinks it OK. Otherwise, URLMonitor will send alerts according to the predefined tolerance on the lateness of the target page keeping its state in sync.

In case that URLMonitor is used as a dependency with the disableMode enabled, it checks mtime of the page to determine the skipping status. If CheckETag is set to be true and the request is HEAD, it will only checks the etag to determine the skipping status.

Author:

yannanlu@yahoo.com

Field Summary

Fields inherited from class org.qbroker.monitor.Monitor

actionCount, actionGroup, aPatternGroup, cachedSkip, category, dependencyGroup, description, disabledWithReport, disableMode, exceptionCount, exceptionTolerance, FILE_SEPARATOR, formatText, keyList, maxPage, maxRetry, name, normalStep, pm, previousStatus, repeatPeriod, report, reportMode, reportName, resolution, serialNumber, site, skip, statsLogger, statusOffset, statusText, step, template, timeFormat, timeTemplate, tolerance, type, xPatternGroup

Fields inherited from interface org.qbroker.monitor.MonitorReport

DISABLED, EXCEPTION, NOSKIP, REPORT_CACHED, REPORT_CLUSTER, REPORT_FINAL, REPORT_FLOW, REPORT_LOCAL, REPORT_NODE, REPORT_NONE, REPORT_SHARED, SKIPPED

Constructor Summary

Constructors

Constructor and Description
URLMonitor(java.util.Map props)

Method Summary

Modifier and Type	Method and Description
java.util.Map<java.lang.String,java.lang.Object>	checkpoint() returns the checkpoint Map for the action
void	destroy() closes and releases all opened resources
protected void	finalize()
java.util.Map<java.lang.String,java.lang.Object>	generateReport(long currentTime) generates a report on a monitored entity and returns it as a Map.
Event	performAction(int status, long currentTime, java.util.Map<java.lang.String,java.lang.Object> latest) examines the report on the monitored entity and reacts to it as an action
void	restoreFromCheckpoint(java.util.Map<java.lang.String,java.lang.Object> chkpt) restores the state of the action from the checkpoint Map

Methods inherited from class org.qbroker.monitor.Monitor

getName, getReportKeys, getReportMode, getReportName, getSkippingStatus, initTimeTemplate, updateContent

Methods inherited from class java.lang.Object

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

Constructor Detail

URLMonitor

public URLMonitor(java.util.Map props)

Method Detail

generateReport

public java.util.Map<java.lang.String,java.lang.Object> generateReport(long currentTime)
                                                                throws java.io.IOException

Description copied from interface: MonitorReport

generates a report on a monitored entity and returns it as a Map. The report Map will be passed to the associated MonitorAction as an opaque object. The action object is supposed to know how to retrieve the information from the report Map.

Specified by:

generateReport in interface MonitorReport

Specified by:

generateReport in class Monitor

Throws:

java.io.IOException

performAction

public Event performAction(int status,
                           long currentTime,
                           java.util.Map<java.lang.String,java.lang.Object> latest)

Description copied from interface: MonitorAction

examines the report on the monitored entity and reacts to it as an action

Specified by:

performAction in interface MonitorAction

Specified by:

performAction in class Monitor

checkpoint

public java.util.Map<java.lang.String,java.lang.Object> checkpoint()

Description copied from interface: MonitorAction

returns the checkpoint Map for the action

Specified by:

checkpoint in interface MonitorAction

Overrides:

checkpoint in class Monitor

restoreFromCheckpoint

public void restoreFromCheckpoint(java.util.Map<java.lang.String,java.lang.Object> chkpt)

Description copied from interface: MonitorAction

restores the state of the action from the checkpoint Map

Specified by:

restoreFromCheckpoint in interface MonitorAction

Overrides:

restoreFromCheckpoint in class Monitor

destroy

public void destroy()

Description copied from interface: MonitorReport

closes and releases all opened resources

Specified by:

destroy in interface MonitorReport

Overrides:

destroy in class Monitor

finalize

protected void finalize()

Overrides:

finalize in class Monitor