util.rmi
Class AbstractRmiListener

java.lang.Object
  util.PropertyContainer
      util.rmi.RmiPropertyContainer
          util.rmi.AbstractRmiListener

All Implemented Interfaces:

Cloneable, Remote, EventListener, ExitCleaning, Initializable, PropertyBearing, RmiEventListener, RmiListener, RmiPropertyBearing

Direct Known Subclasses:

AbstractErrorHandler, AbstractRmiCasterAndListener, ApplicationJoiner, DailyDump, DailyDumpRepository, DatabaseNow, ErrorRelay, FieldSerializer, FileDump, FitsRelay, FitsUpdateListener, JImageURLButton.ImageListener, JLaunchBox, MasterListener, MessageListener, MyRmiListener, PointingGrabber, ReadoutRepository, StatusSerializer, TransferListener

public abstract class AbstractRmiListener
extends RmiPropertyContainer
implements RmiEventListener, ExitCleaning

The common base class for all implementations of rmi-based listeners. It provides base implementation for the RmiEventListener methods. The isConnected() method returns true. The connection to the casters is checked with the innner AbstractRmiListener.CheckCaster class. The functionality of this class is served with a TimerTask at a fixed delay. Please note that subclasses should always use the getCaster(java.lang.String) method to derive a remote reference to the caster this listener wants to subscribe to together with the registerAtCaster(util.rmi.RmiCaster, java.lang.Class) method.

The #rebind method is also served, allowing first for a deregistration at the appropriate caster, see deregisterAtCaster(util.rmi.RmiCaster, java.lang.Class), a timed wait and a new cycle of registering. Note that during the rebinding phase, the #isValid timer task is blocked.

For convenience this abstract base class provides the two methods defined in the ListenerControlling interface. They default to the #initBinding and releaseBinding(java.lang.String) methods. Daugther classes that do not require special treatment of the listener control capabilities can therefore simply implement the ListenerControlling interface without further caring about an implementation.

Nested Class Summary

private class	AbstractRmiListener.BindingThread A thread that initiates a binding to a special service.
private class	AbstractRmiListener.CheckCaster Checks if all casters are still valid references.
private static class	AbstractRmiListener.ServiceReference Combines a service name, which should be a valid registry reference and a service class to a single Map key.

Nested classes/interfaces inherited from class util.PropertyContainer

PropertyContainer.URLResource

Field Summary

private boolean	cancel Cancel the get caster loop.
private TimerTask	check The timer task to run.
private static long	DEFALIVE The default connection check intervall, ms (1min).
private static int	DEFEXPORTPORT The port at which unicast should export.
private static long	DEFINIT The default connection check initial delay, ms (1min).
private static int	DEFRETRY The default maximum nuber of binding retries.
private static long	DEFRETRYSLEEP The default sleep intervall between binding retries, in ms.
private static long	DEFSHUTDOWNDELAY The default shutdown delay time, 5 sec.
static String	KEY_ALIVE The key to the connection check intervall.
static String	KEY_EXPORTPORT For unicast exports, the port at which we should export.
static String	KEY_INIT The key to the connection check initial delay.
static String	KEY_LISTENERNAME The key to the name of this listener.
static String	KEY_RETRY The key in the properties for the maximum nuber of binding retries.
static String	KEY_RETRYSLEEP The key for the sleep intervall between binding retries.
static String	KEY_SHUTDOWNDELAY The time delay from receiving quit-command until orderly shutdown.
private Map<AbstractRmiListener.ServiceReference,RmiCaster>	namingToRemote The map of full URL names to RMICaster references.
private List<AbstractRmiListener.BindingThread>	running A list of currently active binding thread.
private static Timer	validate The timer to schedule the #isValid timer task.

Fields inherited from class util.PropertyContainer

KEY_LISTSEPARATOR, KEY_LOCALECOUNTRY, KEY_LOCALELANGUAGE, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR, KEY_NOINITONCREATE, KEY_RESOURCEBUNDLES

Fields inherited from interface util.PropertyBearing

CONFIG, KEY_CLASS, KEY_URLRESOURCES, KEY_URLUSECONFIG, KEY_URLUSECURRENT, KEY_URLUSEHOME

Constructor Summary

protected

AbstractRmiListener(Map<String,String> prop) Constructs a new rmi-listener base class.

Method Summary

private void	addCasterForCheck(String name, Class<?> only, RmiCaster server) Adds a server defined by its binding reference and its service class to our look-up table that checks routinely for validity of the server.
boolean	allBound() Returns true, if all bindings are valid in the sense that there is no active binding thread.
boolean	blockBinding(String name) Initializes a binding without type constraints.
boolean	blockBinding(String name, Class<?> only) Initializes a binding.
protected abstract boolean	deregisterAtCaster(RmiCaster caster, Class<?> reference) Deregisters this listener at a certain csater.
void	disconnect(RmiCaster from) Called by the caster to signal that the listener should remove itself.
void	exit() Prior to performing a shutdown, we de-register from all valid casters.
private RmiCaster	getCaster(String name) Returns a remote reference to the rmi-caster resolvable by the given name.
InetAddress	getIP() Returns the IP-address of the machine this listener runs on.
String	getListenerName() Returns the property name KEY_LISTENERNAME.
boolean	isConnected() Returns true.
protected String	listenerName() Returns the property name KEY_LISTENERNAME.
protected abstract boolean	registerAtCaster(RmiCaster caster, Class<?> reference) Registers this listener at a certain caster.
boolean	releaseBinding(String name) Releases a binding without type constraints.
boolean	releaseBinding(String name, Class<?> only) Releases a binding.
protected double	rescanned(String key, String old, String newval) Reloads all relevant parameters for this listener to allow subclasses to become reloadable.
Thread	startBinding(String name) Initializes a binding without type constraints.
Thread	startBinding(String name, Class<?> only) Initializes a binding.

Methods inherited from class util.rmi.RmiPropertyContainer

containsRemoteProperty, getRemoteProperties, getRemoteProperty, setRemoteProperty

Methods inherited from class util.PropertyContainer

augment, augment, augment, clone, createFrom, createFrom, createFrom, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getLocalClassLoader, getLocalized, getLocalized, getLocalizedString, getLocalizedString, getProperties, getPropertiesToKey, getPropertiesToKey, getProperty, getResource, getResourceAsStream, getResourceFromKey, getResources, has, init, isNew, keyCreate, keyCreate, parseObject, reload, reload, removeProperty, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object

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

Field Detail

KEY_LISTENERNAME

public static final String KEY_LISTENERNAME

The key to the name of this listener.

See Also:

Constant Field Values

KEY_RETRY

public static final String KEY_RETRY

The key in the properties for the maximum nuber of binding retries.

See Also:

Constant Field Values

KEY_RETRYSLEEP

public static final String KEY_RETRYSLEEP

The key for the sleep intervall between binding retries.

See Also:

Constant Field Values

KEY_ALIVE

public static final String KEY_ALIVE

The key to the connection check intervall.

See Also:

Constant Field Values

KEY_INIT

public static final String KEY_INIT

The key to the connection check initial delay.

See Also:

Constant Field Values

KEY_SHUTDOWNDELAY

public static final String KEY_SHUTDOWNDELAY

The time delay from receiving quit-command until orderly shutdown.

See Also:

Constant Field Values

KEY_EXPORTPORT

public static final String KEY_EXPORTPORT

For unicast exports, the port at which we should export.

See Also:

Constant Field Values

DEFEXPORTPORT

private static final int DEFEXPORTPORT

The port at which unicast should export. Zero means anonymous port.

See Also:

Constant Field Values

DEFRETRY

private static final int DEFRETRY

The default maximum nuber of binding retries.

See Also:

Constant Field Values

DEFRETRYSLEEP

private static final long DEFRETRYSLEEP

The default sleep intervall between binding retries, in ms.

See Also:

Constant Field Values

DEFALIVE

private static final long DEFALIVE

The default connection check intervall, ms (1min).

See Also:

Constant Field Values

DEFINIT

private static final long DEFINIT

The default connection check initial delay, ms (1min).

See Also:

Constant Field Values

DEFSHUTDOWNDELAY

private static final long DEFSHUTDOWNDELAY

The default shutdown delay time, 5 sec.

See Also:

Constant Field Values

validate

private static Timer validate

The timer to schedule the #isValid timer task.

namingToRemote

private Map<AbstractRmiListener.ServiceReference,RmiCaster> namingToRemote

The map of full URL names to RMICaster references.

running

private List<AbstractRmiListener.BindingThread> running

A list of currently active binding thread.

check

private TimerTask check

The timer task to run.

cancel

private boolean cancel

Cancel the get caster loop.

Constructor Detail

AbstractRmiListener

protected AbstractRmiListener(Map<String,String> prop)

Constructs a new rmi-listener base class. The timer associated with the rmi listener is constructed, but not timer task is scheduled. This should occur on the first call to the #initBinding call.
Note that this class does not export itself as a unicast remote object.

Method Detail

exit

public void exit()

Prior to performing a shutdown, we de-register from all valid casters. We iterate through our the values of our look-up table and directly call deregisterAtCaster(util.rmi.RmiCaster, java.lang.Class).

Specified by:

exit in interface ExitCleaning

rescanned

protected double rescanned(String key,
                           String old,
                           String newval)

Reloads all relevant parameters for this listener to allow subclasses to become reloadable.

Overrides:

rescanned in class PropertyContainer

blockBinding

public boolean blockBinding(String name)

Initializes a binding without type constraints. This is a blocking method.

Returns:

True on success

blockBinding

public boolean blockBinding(String name,
                            Class<?> only)

Initializes a binding. This means

• The argument string is converted into a remote reference via a direct registry look-up.
• If the remote reference is an RmiCaster the listener registers itself to the caster by a call to the (abstract) registerAtCaster(util.rmi.RmiCaster, java.lang.Class) method.
• If this call returns true the name <-> remote mapping is stored in the namingToRemote look-up table.
• If no caster check task has been constructed a new AbstractRmiListener.CheckCaster thread is constructed and scheduled in the timer task.

This method blocks until registering was successful.

Returns:

True on success

startBinding

public Thread startBinding(String name)

Initializes a binding without type constraints. This is a blocking method.

startBinding

public Thread startBinding(String name,
                           Class<?> only)

Initializes a binding. This means

• The argument string is converted into a remote reference via a direct registry look-up.
• If the remote reference is an RmiCaster the listener registers itself to the caster by a call to the (abstract) registerAtCaster(util.rmi.RmiCaster, java.lang.Class) method.
• If this call returns true the name <-> remote mapping is stored in the namingToRemote look-up table.
• If no caster check task has been constructed a new AbstractRmiListener.CheckCaster thread is constructed and scheduled in the timer task.

This method does not block until registering was successful.

releaseBinding

public boolean releaseBinding(String name)

Releases a binding without type constraints.

releaseBinding

public boolean releaseBinding(String name,
                              Class<?> only)

Releases a binding. This means

• The argument string is converted into a remote reference via a direct registry look-up.
• If the remote reference is an RmiCaster the listener deregisters itself to the caster by a call to the (abstract) deregisterAtCaster(util.rmi.RmiCaster, java.lang.Class) method.
• If this call returns true the name <-> remote mapping is cleared in the namingToRemote look-up table.

allBound

public boolean allBound()

Returns true, if all bindings are valid in the sense that there is no active binding thread.

getIP

public InetAddress getIP()
                  throws RemoteException

Returns the IP-address of the machine this listener runs on. Uses the getLocalHost of the InetAddress class. If the local host does not have an ip address, null is returned.

Throws:

RemoteException

isConnected

public boolean isConnected()
                    throws RemoteException

Returns true. Called by casters to check if the reference is still valid. Note that the RemoteException this method throws in case of faulty references is the real thing to detect.

Specified by:

isConnected in interface RmiListener

Throws:

RemoteException

disconnect

public void disconnect(RmiCaster from)
                throws RemoteException

Called by the caster to signal that the listener should remove itself. Called normally on caster exit.

Specified by:

disconnect in interface RmiListener

Throws:

RemoteException

addCasterForCheck

private void addCasterForCheck(String name,
                               Class<?> only,
                               RmiCaster server)

Adds a server defined by its binding reference and its service class to our look-up table that checks routinely for validity of the server.

getListenerName

public String getListenerName()
                       throws RemoteException

Returns the property name KEY_LISTENERNAME.

Specified by:

getListenerName in interface RmiEventListener

Throws:

RemoteException

listenerName

protected String listenerName()

Returns the property name KEY_LISTENERNAME.

registerAtCaster

protected abstract boolean registerAtCaster(RmiCaster caster,
                                            Class<?> reference)

Registers this listener at a certain caster. This method is abstract because it is not a-priori known to which type of caster this listener should subscribe, nor which listener type this instance is. If the registering process was successful this method should return true.

Returns:

True, if this listener can register at the specified caster

deregisterAtCaster

protected abstract boolean deregisterAtCaster(RmiCaster caster,
                                              Class<?> reference)

Deregisters this listener at a certain csater. This method is abstract because it is not a-priori known to which type of caster this listener should subscribe, nor which listener type this instance is. If the deregistering process was successful this method should return true.

Returns:

True, if this listener can deregister at the specified caster

getCaster

private RmiCaster getCaster(String name)

Returns a remote reference to the rmi-caster resolvable by the given name. If registry-lookup is successful, a mapping of the name to the remote caster instance is stored in the namingToRemote hash-map. This method is called only in a synchronized on namingToRemote state.