stella

Class MasterErrorHandler

java.lang.Object

util.PropertyContainer

util.PropertyResources

util.rmi.RmiPropertyContainer

util.rmi.AbstractRmiListener

stella.AbstractErrorHandler

stella.MasterErrorHandler

All Implemented Interfaces:

Cloneable, Remote, EventListener, ClusterDepending, ErrorHandling, ErrorListener, RmiErrorListener, RmiWeatherListener, WeatherListener, ExitCleaning, Initializable, PropertySupplying, ResourceSupplying, RmiEventListener, RmiListener, RmiPropertyBearing

public class MasterErrorHandler
extends AbstractErrorHandler
implements WeatherListener, RmiWeatherListener, RmiErrorListener, Initializable

A collection of ErrorFinalizing objects. Incoming error messages are queried for their required follow-up action. A lookup table is then used to match the required follow-up action to an ErrorFinalizing object. The error is now passed to the ErrorFinalizing.finalizeError(target.TargetDefinition, stella.ErrorEvent, stella.CommandLaunching[], stella.Sequencing<?>, stella.ParameterClustering) method which should return fast and does all necessary steps to recover from the error. If recovery fails for any reason, i.e. if ErrorFinalizing.finalizeError(target.TargetDefinition, stella.ErrorEvent, stella.CommandLaunching[], stella.Sequencing<?>, stella.ParameterClustering) returns false, or if the error received cannot be matched to a finalizer, the fatalError(stella.ErrorEvent) method is called.

Additionally, errors related to Handable targets are treated. Whenever a TargetDefinition is started using the startTarget(stella.Handable) method, it is copied into the current list. PickConnected errors are then first assigned to the most currently started target. If this target has parents that are additionally in the current list, the error is propagated up until either no further parent is assigned to a target or if the parent in question is not in the current list. Targets may react to this errors with abort or retries, see e.g. DOMTarget.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	MasterErrorHandler.NoneErrorFinalizer A default finalizer class for ErrorEvent.NONE follow-ups.

Nested classes/interfaces inherited from class util.PropertyResources

PropertyResources.Load, PropertyResources.URLResource

Field Summary

Fields

Modifier and Type	Field and Description
private List<Handable>	current A list of currently started targets for PickConnected errors.
private static String	DEFPICKREPLACE Per default, we use a mail finalizer on pick-realated errors.
private Map<String,ErrorFinalizing>	handle A lookup table linking follow-ups to error handlers.
private boolean	ignore A boolean indicating that incoming error should be ignored.
static String	KEY_HANDLERS The key to the coma-separated list of error finalizers.
static String	KEY_PICKREPLACE Pick connected errors with NONE get a different error handler.
static String	KEY_REMOTE The key to the remote error casters.
static String	KEY_WEATHER The key to the remote weather caster.
private Sequencing	sequencer A link to the main sequencer.
private CommandLaunching[]	servers A link to the command servers.
private ParameterClustering	set A link to the main parameter set.
private WeatherSurveying	weather The local weather station if any.

Fields inherited from class util.rmi.AbstractRmiListener

KEY_ALIVE, KEY_EXPORTPORT, KEY_INIT, KEY_LISTENERNAME, KEY_RETRY, KEY_RETRYSLEEP, KEY_SHUTDOWNDELAY

Fields inherited from class util.PropertyResources

KEY_NOINITONCREATE, POSTFIX_ALPHABET, POSTFIX_BYTES, POSTFIX_DIR, POSTFIX_EXT, POSTFIX_FILE, POSTFIX_LIST, POSTFIX_MODTIME, POSTFIX_URL

Fields inherited from class util.PropertyContainer

KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.PropertySupplying

CONFIG, KEY_CLASS

Fields inherited from interface util.ResourceSupplying

KEY_URLRESOURCES, KEY_URLUSECONFIG, KEY_URLUSECURRENT, KEY_URLUSEHOME

Constructor Summary

Constructors

Constructor and Description
MasterErrorHandler(Map<String,String> prop) Constructs a new simple error handler.

Method Summary

Modifier and Type	Method and Description
protected boolean	deregisterAtCaster(RmiCaster caster, Class service) Adds the ability to deregister at rmi-weather casters.
boolean	doAbort() Returns true if the error handler is dealing with a target abort.
void	endTarget(Handable end) Removes a target from the error-handlers current list.
void	errorOccured(ErrorEvent ee) The incomming errors.
void	exit() Signals that the error handler is shuting down and incoming errors should be ignored.
private void	fatalError(ErrorEvent ee) This error handler is invoked when everything else fails.
void	init() Registers at a remote weather caster to tranform bad weather events into BadWeather and GoodWeather errors.
private void	notifyTargets(ErrorEvent ee, ErrorFinalizing finish, ParameterClustering set) If a PickConnected error was registered, the list of currently active targets is traversed.
protected boolean	registerAtCaster(RmiCaster caster, Class service) Adds the ability to register at rmi-weather casters.
void	registerGlobals(ParameterClustering cluster) Registers the parameter cluster.
void	registerLauncher(CommandLaunching[] device) Registers the command servers.
void	registerMonitor(Object sleeper) Registers the monitor.
void	registerSequencer(Sequencing seq) Registers the command sequencer.
void	registerWeather(WeatherSurveying fake) Registers a local weather station to the error handler.
void	rmiErrorOccured(ErrorEvent ee) This method is invoked by remote error casters.
void	rmiWeatherChanged(WeatherEvent we) Handles weather events.
void	setEnabled(boolean accept) Enables the error handler, meaning that incoming errors are no longer ignored.
void	startTarget(Handable start) Adds a target to the handler's current list.
void	weatherChanged(WeatherEvent we) Handles weather events.

Methods inherited from class stella.AbstractErrorHandler

createErrorHandler

Methods inherited from class util.rmi.AbstractRmiListener

allBound, blockBinding, blockBinding, disconnect, getIP, getListenerName, isConnected, listenerName, releaseBinding, releaseBinding, rescanned, startBinding, startBinding

Methods inherited from class util.rmi.RmiPropertyContainer

containsRemoteProperty, getRemoteProperties, getRemoteProperty, setRemoteProperty

Methods inherited from class util.PropertyResources

clone, createFrom, createFrom, createFrom, createInstance, getApplet, getAsResources, getLocate, getPropertiesToKey, getPropertiesToKey, getResource, getResourceAsStream, getResourceFromKey, getResources, hasLocalURLs, initProperties, keyCreate, keyCreate, reload, setApplet

Methods inherited from class util.PropertyContainer

augment, augment, augment, augment, augment, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, isNew, parseObject, parseObject, reload, removeProperty, requires, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface util.rmi.RmiEventListener

getListenerName

Methods inherited from interface util.rmi.RmiListener

disconnect, isConnected

Methods inherited from interface util.PropertySupplying

defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, parseObject, removeProperty, setObject, setProperty, stringProperties

Field Detail

KEY_HANDLERS

public static final String KEY_HANDLERS

The key to the coma-separated list of error finalizers.

See Also:

Constant Field Values

KEY_WEATHER

public static final String KEY_WEATHER

The key to the remote weather caster. Must be matched.

See Also:

Constant Field Values

KEY_REMOTE

public static final String KEY_REMOTE

The key to the remote error casters. Points to a comma-separated list.

See Also:

Constant Field Values

KEY_PICKREPLACE

public static final String KEY_PICKREPLACE

Pick connected errors with NONE get a different error handler.

See Also:

Constant Field Values

DEFPICKREPLACE

private static final String DEFPICKREPLACE

Per default, we use a mail finalizer on pick-realated errors.

See Also:

Constant Field Values

handle

private Map<String,ErrorFinalizing> handle

A lookup table linking follow-ups to error handlers.

servers

private CommandLaunching[] servers

A link to the command servers. They additionally act as error casters.

sequencer

private Sequencing sequencer

A link to the main sequencer.

set

private ParameterClustering set

A link to the main parameter set. Used with pipe-raised errors.

weather

private WeatherSurveying weather

The local weather station if any.

ignore

private boolean ignore

A boolean indicating that incoming error should be ignored.

current

private List<Handable> current

A list of currently started targets for PickConnected errors.

Constructor Detail

MasterErrorHandler

public MasterErrorHandler(Map<String,String> prop)
                   throws RemoteException

Constructs a new simple error handler. Registering the command servers, the sequencer, and the scheduler are done in the parent class.

Throws:

RemoteException

Method Detail

init

public void init()

Registers at a remote weather caster to tranform bad weather events into BadWeather and GoodWeather errors. Additionally registers at all remote error casters given with the KEY_REMOTE property. Scans the KEY_HANDLERS key to construct and load appropriate ErrorFinalizers for handling of incoming errors. If the ErrorEvent.NONE has no explicit handler specified, the MasterErrorHandler.NoneErrorFinalizer is used.

Specified by:

init in interface Initializable

setEnabled

public void setEnabled(boolean accept)

Enables the error handler, meaning that incoming errors are no longer ignored.

Specified by:

setEnabled in interface ErrorHandling

registerLauncher

public void registerLauncher(CommandLaunching[] device)

Registers the command servers. Additionally, this devices registers itself as an error listener to all command servers if they can be cast to error casters. Note that remote error caster registration is done at construct using the KEY_REMOTE.

Specified by:

registerLauncher in interface ErrorHandling

registerSequencer

public void registerSequencer(Sequencing seq)

Registers the command sequencer. In case of errors, the flow of command might change. This is directly reported to the sequencer instance.

Specified by:

registerSequencer in interface ErrorHandling

registerWeather

public void registerWeather(WeatherSurveying fake)

Registers a local weather station to the error handler. This it not identical to registering to a remote weather station using the KEY_WEATHER key. Local weather station may be present in case of simulated action only.

Specified by:

registerWeather in interface ErrorHandling

registerGlobals

public void registerGlobals(ParameterClustering cluster)

Registers the parameter cluster. Parameters that are error casting will be enlistened to the error handler.

Specified by:

registerGlobals in interface ClusterDepending

registerMonitor

public void registerMonitor(Object sleeper)

Registers the monitor. In most cases this is the master mind who might be awaken by certain ErrorFinalizing instances. This method should only be called after all error finalizers have been initialized.

Specified by:

registerMonitor in interface ErrorHandling

startTarget

public void startTarget(Handable start)

Adds a target to the handler's current list. All targets stored there may receive PickConnected errors. If such an error is received, the most recently added targets receives it first.

Specified by:

startTarget in interface ErrorHandling

endTarget

public void endTarget(Handable end)

Removes a target from the error-handlers current list. Errors occuring later may not back-react on this target.

Specified by:

endTarget in interface ErrorHandling

doAbort

public boolean doAbort()

Returns true if the error handler is dealing with a target abort. This error is unique because it should also block sequence loading or target selection in the master mind.

Specified by:

doAbort in interface ErrorHandling

exit

public void exit()

Signals that the error handler is shuting down and incoming errors should be ignored. Additionally, we de-register from all error-casting parameters.

Specified by:

exit in interface ExitCleaning

Overrides:

exit in class AbstractRmiListener

rmiWeatherChanged

public void rmiWeatherChanged(WeatherEvent we)
                       throws RemoteException

Handles weather events. Initiates shutdown if weather is bad.

Specified by:

rmiWeatherChanged in interface RmiWeatherListener

Throws:

RemoteException

weatherChanged

public void weatherChanged(WeatherEvent we)

Handles weather events. Initiates shutdown if weather is bad.

Specified by:

weatherChanged in interface WeatherListener

rmiErrorOccured

public void rmiErrorOccured(ErrorEvent ee)
                     throws RemoteException

This method is invoked by remote error casters. It is re-directed to the local errorOccured(stella.ErrorEvent) method.

Specified by:

rmiErrorOccured in interface RmiErrorListener

Throws:

RemoteException

errorOccured

public void errorOccured(ErrorEvent ee)

The incomming errors. Errors are queried for theit follow-up and the appropriate ErrorFinalizing object is loaded and executed. If the error has a raised pipe-flag, it is passed to the parameter cluster registered to this error handler.

To judge fast return from this event-handling methods, consider:

• All targets are notified on the error if the error is PickConnected. Callers can be assured that all targets have their fields updated on method return.
• If the error is piping or ParameterConnected the caller can be assured that the parameter set has been notified.
• All errors with an alive ErrorFinalizing method spark invocation of the appropriate method. Most finalizers will run in their own thread, so no statement can be made on their status after method call.

Specified by:

errorOccured in interface ErrorListener

registerAtCaster

protected boolean registerAtCaster(RmiCaster caster,
                                   Class service)

Adds the ability to register at rmi-weather casters. If the argument handed over is not of the appropriate instance the superclass's registerAtCaster method is called.

Specified by:

registerAtCaster in class AbstractRmiListener

deregisterAtCaster

protected boolean deregisterAtCaster(RmiCaster caster,
                                     Class service)

Adds the ability to deregister at rmi-weather casters. If the argument handed over is not of the appropriate instance the superclass's deregisterAtCaster method is called.

Specified by:

deregisterAtCaster in class AbstractRmiListener

notifyTargets

private void notifyTargets(ErrorEvent ee,
                           ErrorFinalizing finish,
                           ParameterClustering set)

If a PickConnected error was registered, the list of currently active targets is traversed. Starting from the currently executing target (the last one added with startTarget(stella.Handable)), all precursors present in current are notified. The individual target getting notifies receives the error on its appropriate end. An error that occured in the currently observed target radiates to Handable.errorMain(stella.ErrorEvent, stella.ErrorFinalizing, stella.ParameterClustering), while precursors that have the currently queried target as successor or daughter are notified accordingly.

fatalError

private void fatalError(ErrorEvent ee)

This error handler is invoked when everything else fails. It does a shutdown on all instruments by casting the CommandLaunching.getShutdownCommand() to the peripherals.