OpenNMS API 1.1.4

org.opennms.netmgt.poller
Class DnsMonitor

java.lang.Object
  extended byorg.opennms.netmgt.poller.IPv4LatencyMonitor
      extended byorg.opennms.netmgt.poller.DnsMonitor
All Implemented Interfaces:
ServiceMonitor

final class DnsMonitor
extends IPv4LatencyMonitor

This class is designed to be used by the service poller framework to test the availability of the DNS service on remote interfaces. The class implements the ServiceMonitor interface that allows it to be used along with other plug-ins by the service poller framework.

Author:
Tarus Balog, OpenNMS

Field Summary
private static int DEFAULT_PORT
          Default DNS port.
private static int DEFAULT_RETRY
          Default retries.
private static int DEFAULT_TIMEOUT
          Default timeout.
(package private) static java.lang.String DS_NAME
          RRD data source name which doubles as the RRD file name.
 
Fields inherited from interface org.opennms.netmgt.poller.ServiceMonitor
SERVICE_AVAILABLE, SERVICE_STATUS_MASK, SERVICE_UNAVAILABLE, SERVICE_UNRESPONSIVE, SURPRESS_EVENT_MASK
 
Constructor Summary
(package private) DnsMonitor()
           
 
Method Summary
 boolean createRRD(java.lang.String repository, java.net.InetAddress addr, java.lang.String dsName, Package pkg)
          Create an RRD database file for storing latency/response time data.
 void initialize(java.util.Map parameters)
          This method is called after the framework creates an instance of the plug-in.
 void initialize(NetworkInterface iface)
          This method is called whenever a new interface that supports the plug-in service is added to the scheduling system.
 int poll(NetworkInterface iface, java.util.Map parameters, Package pkg)
          Poll the specified address for DNS service availability.
 void release()
          This method is called whenever the plug-in is being unloaded, normally during framework exit.
 void release(NetworkInterface iface)
          This method is the called whenever an interface is being removed from the scheduler.
 void updateRRD(java.lang.String repository, java.net.InetAddress addr, java.lang.String dsName, long value, Package pkg)
          Update an RRD database file with latency/response time data.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_PORT

private static final int DEFAULT_PORT
Default DNS port.

See Also:
Constant Field Values

DEFAULT_RETRY

private static final int DEFAULT_RETRY
Default retries.

See Also:
Constant Field Values

DEFAULT_TIMEOUT

private static final int DEFAULT_TIMEOUT
Default timeout. Specifies how long (in milliseconds) to block waiting for data from the monitored interface.

See Also:
Constant Field Values

DS_NAME

static java.lang.String DS_NAME
RRD data source name which doubles as the RRD file name.

Constructor Detail

DnsMonitor

DnsMonitor()
Method Detail

poll

public int poll(NetworkInterface iface,
                java.util.Map parameters,
                Package pkg)

Poll the specified address for DNS service availability.

During the poll an DNS address request query packet is generated for hostname 'localhost'. The query is sent via UDP socket to the interface at the specified port (by default UDP port 53). If a response is received, it is parsed and validated. If the DNS lookup was successful the service status is set to SERVICE_AVAILABLE and the method returns.

Parameters:
iface - The network interface to test the service on.
parameters - The package parameters (timeout, retry, etc...) to be used for this poll.
Returns:
The availibility of the interface and if a transition event should be supressed.
See Also:
ServiceMonitor.SURPRESS_EVENT_MASK, ServiceMonitor.SERVICE_AVAILABLE, ServiceMonitor.SERVICE_UNAVAILABLE

initialize

public void initialize(java.util.Map 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 retreive 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 montior may throw a ServiceMonitorException. If the plug-in throws an exception then the plug-in will be disabled in the framework.

Specified by:
initialize in interface ServiceMonitor
Parameters:
parameters - Not currently used
Throws:
java.lang.RuntimeException - Thrown if an unrecoverable error occurs that prevents the plug-in from functioning.

release

public 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.

Specified by:
release in interface ServiceMonitor
Throws:
java.lang.RuntimeException - Thrown if an error occurs during deallocation.

initialize

public void initialize(NetworkInterface iface)

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.

Specified by:
initialize in interface ServiceMonitor
Parameters:
iface - The network interface to be added to the scheduler.
Throws:
java.lang.RuntimeException - Thrown if an unrecoverable error occurs that prevents the interface from being monitored.
NetworkInterfaceNotSupportedException - Thrown if the passed interface is invalid for this monitor.

release

public void release(NetworkInterface iface)

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.

Specified by:
release in interface ServiceMonitor
Parameters:
iface - The network interface that was being monitored.
Throws:
java.lang.RuntimeException - Thrown if an unrecoverable error occurs that prevents the interface from being monitored.

createRRD

public boolean createRRD(java.lang.String repository,
                         java.net.InetAddress addr,
                         java.lang.String dsName,
                         Package pkg)
                  throws RrdException
Create an RRD database file for storing latency/response time data.

Parameters:
repository - path to the RRD file repository
addr - interface address
dsName - data source/RRD file name
Returns:
true if RRD file successfully created, false otherwise
Throws:
RrdException

updateRRD

public void updateRRD(java.lang.String repository,
                      java.net.InetAddress addr,
                      java.lang.String dsName,
                      long value,
                      Package pkg)
Update an RRD database file with latency/response time data.

Parameters:
repository - path to the RRD file repository
addr - interface address
value - value to update the RRD file with
Returns:
true if RRD file successfully created, false otherwise

OpenNMS API 1.1.4

Generated by eevans on November 11 2004 1600.