org.opennms.netmgt.poller

Interface ServiceMonitor

All Known Implementing Classes:

AbstractServiceMonitor, AvailabilityMonitor, BgpSessionMonitor, BSFMonitor, CiscoIpSlaMonitor, CiscoPingMibMonitor, CitrixMonitor, DhcpMonitor, DiskUsageMonitor, DnsMonitor, DNSResolutionMonitor, DominoIIOPMonitor, EndPointMonitor, FtpMonitor, GpMonitor, HostResourceSwRunMonitor, HttpMonitor, HttpsMonitor, IcmpMonitor, ImapMonitor, JBossMonitor, JCifsMonitor, JDBCMonitor, JDBCQueryMonitor, JDBCStoredProcedureMonitor, JMXMonitor, JMXSecureMonitor, JschSshMonitor, Jsr160Monitor, LatencyStoringServiceMonitorAdaptor, LdapMonitor, LdapsMonitor, LoopMonitor, MailTransportMonitor, MemcachedMonitor, MobileMsgSequenceMonitor, MX4JMonitor, NrpeMonitor, NsclientMonitor, NtpMonitor, OmsaStorageMonitor, OpenManageChassisMonitor, PageSequenceMonitor, PassiveServiceMonitor, PercMonitor, Pop3Monitor, RadiusAuthMonitor, SeleniumMonitor, SmbMonitor, SMSPingMonitor, SmtpMonitor, SnmpMonitor, SnmpMonitorStrategy, SshMonitor, StrafePingMonitor, TcpMonitor, TrivialTimeMonitor, WebMonitor, Win32ServiceMonitor, WmiMonitor, XmpMonitor

public interface ServiceMonitor

This is the interface that must be implemented by each poller plugin in the framework. This well defined interface allows the framework to treat each plugin identically.

When a service monitor plug-in is loaded and initialized, the framework will initialize the monitor by calling the initialize() method. Likewise, when the monitor is unloaded the framework calls the release() method is called. If the plug-in needs to save or read any configuration information after the initialize() call, a reference to the proxy object should be saved at initialization.

NOTE: The plug-in poll() must be thread safe in order to operate. Any synchronized methods or data accessed in the poll() can negatively affect the framework if multiple poller threads are blocked on a critical resource. Synchronization issues should be seriously evaluated to ensure that the plug-in scales well to large deployments.

Version:

$Id: $

Author:

Brian Weaver , OpenNMS , Brian Weaver , OpenNMS

Method Summary

Methods

Modifier and Type	Method and Description
void	initialize(Map<String,Object> parameters) This method is called after the framework creates an instance of the plug-in.
void	initialize(MonitoredService svc) This method is called whenever a new interface that supports the plug-in service is added to the scheduling system.
PollStatus	poll(MonitoredService svc, Map<String,Object> parameters) This method is the heart of the plug-in monitor.
void	release() This method is called whenever the plug-in is being unloaded, normally during framework exit.
void	release(MonitoredService svc) This method is the called whenever an interface is being removed from the scheduler.

Method Detail

initialize

void initialize(Map<String,Object> parameters)

This method is called after the framework creates an instance of the plug-in. The framework passes the object a proxy object that can be used to retrieve configuration information specific to the plug-in. Additionally, any parameters for the plug-in from the package definition are passed using the parameters element.

If there is a critical error, like missing service libraries, the the Monitor may throw a ServiceMonitorException. If the plug-in throws an exception then the plug-in will be disabled in the framework.

Parameters:

parameters - Not currently used

Throws:

RuntimeException - Thrown if an unrecoverable error occurs that prevents the plug-in from functioning.

release

void release()

This method is called whenever the plug-in is being unloaded, normally during framework exit. During this time the framework may release any resource and save any state information using the proxy object from the initialization routine.

Even if the plug-in throws a monitor exception, it will not prevent the plug-in from being unloaded. The plug-in should not return until all of its state information is saved. Once the plug-in returns from this call its configuration proxy object is considered invalid.

Throws:

RuntimeException - Thrown if an error occurs during deallocation.

initialize

void initialize(MonitoredService svc)

This method is called whenever a new interface that supports the plug-in service is added to the scheduling system. The plug-in has the option to load and/or associate configuration information with the interface before the framework begins scheduling the new device.

Should a monitor exception be thrown during an initialization call then the framework will log an error and discard the interface from scheduling.

Parameters:

svc - TODO

Throws:

RuntimeException - Thrown if an unrecoverable error occurs that prevents the interface from being monitored.

release

void release(MonitoredService svc)

This method is the called whenever an interface is being removed from the scheduler. For example, if a service is determined as being no longer supported then this method will be invoked to cleanup any information associated with this device. This gives the implementor of the interface the ability to serialize any data prior to the interface being discarded.

If an exception is thrown during the release the exception will be logged, but the interface will still be discarded for garbage collection.

Parameters:

svc - TODO

Throws:

RuntimeException - Thrown if an unrecoverable error occurs that prevents the interface from being monitored.

poll

PollStatus poll(MonitoredService svc,
              Map<String,Object> parameters)

This method is the heart of the plug-in monitor. Each time an interface requires a check to be performed as defined by the scheduler the poll method is invoked. The poll is passed the interface to check

By default when the status transition from up to down or vice versa the framework will generate an event. Additionally, if the polling interval changes due to an extended unavailability, the framework will generate an additional down event. The plug-in can suppress the generation of the default events by setting the suppress event bit in the returned integer.

Parameters:

svc - TODO

parameters - The package parameters (timeout, retry, etc...) to be used for this poll.

Returns:

The availability of the interface and if a transition event should be suppressed.

Throws:

RuntimeException - Thrown if an unrecoverable error occurs that prevents the interface from being monitored.

See Also:

PollStatus.SERVICE_AVAILABLE, PollStatus.SERVICE_UNAVAILABLE, PollStatus.SERVICE_AVAILABLE, PollStatus.SERVICE_UNAVAILABLE