org.jacorb.notification.filter

Class AbstractFilter

public abstract class AbstractFilter extends Object implements GCDisposable, IServantLifecyle, FilterOperations, JMXManageable, AbstractFilterMBean

The Filter interface defines the behaviors supported by objects which encapsulate constraints used by the proxy objects associated with an event channel in order to determine which events they receive will be forwarded, and which will be discarded. Each object supporting the Filter interface can encapsulate a sequence of any number of constraints. Each event received by a proxy object which has one or more objects supporting the Filter interface associated with it must satisfy at least one of the constraints associated with one of its associated Filter objects in order to be forwarded (either to another proxy object or to the consumer, depending on the type of proxy the filter is associated with), otherwise it will be discarded.
Each constraint encapsulated by a filter object is a structure comprised of two main components. The first component is a sequence of data structures, each of which indicates an event type comprised of a domain and a type name. The second component is a boolean expression over the properties of an event, expressed in some constraint grammar (more on this below). For a given constraint, the sequence of event type structures in the first component nominates a set of event types to which the constraint expression in the second component applies. Each element of the sequence can contain strings which will be matched for equality against the domain_name and type_name fields of each event being evaluated by the filter object, or it could contain strings with wildcard symbols (*), indicating a pattern match should be performed against the type contained in each event, rather than a comparison for equality when determining if the boolean expression should be applied to the event, or the event should simply be discarded without even attempting to apply the boolean expression. Note that an empty sequence included as the first component of a constraint implies that the associated expression applies to all types of events, as does a sequence comprised of a single element whose domain and type name are both set to either the empty string or else the wildcard symbol alone contained in quotes.
The constraint expressions associated with a particular object supporting the Filter interface are expressed as strings which obey the syntax of a particular constraint grammar (i.e., a BNF). Every conformant implementation of this service must support constraint expressions expressed in the default constraint grammar described in Section 2.4, "The Default Filter Constraint Language," on page 2-23. In addition, implementations may support other constraint grammars, and/or users of this service may implement their own filter objects which allow constraints to be expressed in terms of an alternative constraint grammar. As long as such user-defined filter objects support the Filter interface, they can be attached to Proxy or Admin objects in the same fashion as the default Filter objects supported by the implementation of the service are, and the channel should be able to use them to filter events in the same fashion.
The Filter interface supports the operations required to manage the constraints associated with an object instance which supports the interface, along with a readonly attribute which identifies the particular constraint grammar in which the constraints encapsulated by this object have meaning. In addition, the Filter interface supports three variants of the match operation which can be invoked by an associated proxy object upon receipt of an event (the specific variant selected depends upon whether the event is received in the form of an Any, a Structured Event, or a Typed Event), to determine if the event should be forwarded or discarded, based on whether or not the event satisfies at least one criteria encapsulated by the filter object. The Filter interface also supports operations which enable a client to associate with the target filter object any number of "callbacks" which are notified each time there is a change to the list of event types which the constraints encapsulated by the filter object could potentially cause proxies to which the filter is attached to receive. Operations are also defined to support administration of this callback list by unique identifier.

Version: $Id: AbstractFilter.java,v 1.10 2006/01/21 00:45:41 alphonse.bendt Exp $

Author: Alphonse Bendt John Farrell

UNKNOWN: name = "Filter"

Field Summary
protected ReadWriteLockconstraintsLock_
protected Mapconstraints_
contains the associated constraints. as access to constraints_ is controlled by constraintsLock_ its safe to use unsynchronized HashMap here
static intCONSTRAINTS_EMPTY
protected MessageFactorymessageFactory_
static intNO_CONSTRAINTS_MATCH
protected WildcardMapwildcardMap_
Constructor Summary
protected AbstractFilter(Configuration config, EvaluationContextFactory evaluationContextFactory, MessageFactory messageFactory, POA poa)
Method Summary
Objectactivate()
ConstraintInfo[]add_constraints(ConstraintExp[] constraintExp)
The add_constraints operation is invoked by a client in order to associate one or more new constraints with the target filter object.
intattach_callback(NotifySubscribe notifySubscribe)
voidattemptDispose()
voiddeactivate()
voiddestroy()
voiddetach_callback(int id)
voiddispose()
DategetCreationDate()
IteratorgetIterator(Object key)
String[]getJMXNotificationTypes()
StringgetJMXObjectName()
DategetLastUsage()
longgetMatchCount()
longgetMatchStructuredCount()
longgetMatchTypedCount()
POAgetPOA()
ConstraintInfo[]get_all_constraints()
int[]get_callbacks()
ConstraintInfo[]get_constraints(int[] ids)
StringlistContraints()
booleanmatch(Any anyEvent)
protected intmatch_internal(Any anyEvent)
match Any to associated constraints. return the id of the first matching filter or NO_CONSTRAINT.
booleanmatch_structured(StructuredEvent structuredevent)
protected intmatch_structured_internal(StructuredEvent structuredEvent)
match the StructuredEvent to the associated constraints. return the id of the first matching filter or NO_CONSTRAINT.
booleanmatch_typed(Property[] properties)
protected intmatch_typed_internal(Property[] typedEvent)
match the TypedEvent to the associated constraints. return the id of the first matching filter or NO_CONSTRAINT.
voidmodify_constraints(int[] deleteIds, ConstraintInfo[] constraintInfo)
protected intnewConstraintId()
protected abstract FilterConstraintnewFilterConstraint(ConstraintExp constraintExp)
create a new FilterConstraint based on the provided ConstraintExp
ServantnewServant()
voidregisterDisposable(Disposable disposeHook)
voidremove_all_constraints()
voidsetJMXCallback(JMXCallback callback)

Field Detail

constraintsLock_

protected final ReadWriteLock constraintsLock_

constraints_

protected final Map constraints_
contains the associated constraints. as access to constraints_ is controlled by constraintsLock_ its safe to use unsynchronized HashMap here

CONSTRAINTS_EMPTY

public static final int CONSTRAINTS_EMPTY

messageFactory_

protected final MessageFactory messageFactory_

NO_CONSTRAINTS_MATCH

public static final int NO_CONSTRAINTS_MATCH

wildcardMap_

protected final WildcardMap wildcardMap_

Constructor Detail

AbstractFilter

protected AbstractFilter(Configuration config, EvaluationContextFactory evaluationContextFactory, MessageFactory messageFactory, POA poa)

Method Detail

activate

public final Object activate()

add_constraints

public ConstraintInfo[] add_constraints(ConstraintExp[] constraintExp)
The add_constraints operation is invoked by a client in order to associate one or more new constraints with the target filter object. The operation accepts as input a sequence of constraint data structures, each element of which consists of a sequence of event type structures (described in Section 3.2.1, "The Filter Interface," on page 3-14) and a constraint expressed within the constraint grammar supported by the target object. Upon processing each constraint, the target object associates a numeric identifier with the constraint that is unique among all constraints it encapsulates. If any of the constraints in the input sequence is not a valid expression within the supported constraint grammar, the InvalidConstraint exception is raised. This exception contains as data the specific constraint expression that was determined to be invalid. Upon successful processing of all input constraint expressions, the add_constraints operation returns a sequence in which each element will be a structure including one of the input constraint expressions, along with the unique identifier assigned to it by the target filter object.
Note that the semantics of the add_constraints operation are such that its sideeffects are performed atomically upon the target filter object. Once add_constraints is invoked by a client, the target filter object is temporarily disabled from usage by any proxy object it may be associated with. The operation is then carried out, either successfully adding all of the input constraints to the target object or none of them (in the case one of the input expressions was invalid). Upon completion of the operation, the target filter object is effectively re-enabled and can once again be used by associated filter objects in order to make event forwarding decisions.

attach_callback

public int attach_callback(NotifySubscribe notifySubscribe)

attemptDispose

public void attemptDispose()

deactivate

public final void deactivate()

destroy

public void destroy()

UNKNOWN: description = "Destroy this Filter" impact = "ACTION"

detach_callback

public void detach_callback(int id)

dispose

public void dispose()

getCreationDate

public Date getCreationDate()

UNKNOWN: description = "date this filter was created" access = "read-only"

getIterator

public Iterator getIterator(Object key)

getJMXNotificationTypes

public String[] getJMXNotificationTypes()

getJMXObjectName

public final String getJMXObjectName()

getLastUsage

public Date getLastUsage()

UNKNOWN: description = "last usage = invoke match operation" access = "read-only"

getMatchCount

public long getMatchCount()

UNKNOWN: description = "number of match invocations on this filter" access = "read-only"

getMatchStructuredCount

public long getMatchStructuredCount()

UNKNOWN: description = "number of match_structured invocations on this filter" access = "read-only"

getMatchTypedCount

public long getMatchTypedCount()

UNKNOWN: description = "number of match_typed invocations on this filter" access = "read-only"

getPOA

public final POA getPOA()

get_all_constraints

public ConstraintInfo[] get_all_constraints()

get_callbacks

public int[] get_callbacks()

get_constraints

public ConstraintInfo[] get_constraints(int[] ids)

listContraints

public String listContraints()

UNKNOWN: description = "List all Constraints" impact = "INFO"

match

public boolean match(Any anyEvent)

match_internal

protected int match_internal(Any anyEvent)
match Any to associated constraints. return the id of the first matching filter or NO_CONSTRAINT.

match_structured

public boolean match_structured(StructuredEvent structuredevent)

match_structured_internal

protected int match_structured_internal(StructuredEvent structuredEvent)
match the StructuredEvent to the associated constraints. return the id of the first matching filter or NO_CONSTRAINT.

match_typed

public boolean match_typed(Property[] properties)

match_typed_internal

protected int match_typed_internal(Property[] typedEvent)
match the TypedEvent to the associated constraints. return the id of the first matching filter or NO_CONSTRAINT.

modify_constraints

public void modify_constraints(int[] deleteIds, ConstraintInfo[] constraintInfo)

newConstraintId

protected int newConstraintId()

newFilterConstraint

protected abstract FilterConstraint newFilterConstraint(ConstraintExp constraintExp)
create a new FilterConstraint based on the provided ConstraintExp

newServant

public final Servant newServant()

registerDisposable

public void registerDisposable(Disposable disposeHook)

remove_all_constraints

public void remove_all_constraints()

setJMXCallback

public void setJMXCallback(JMXCallback callback)