org.omg.CosNotifyFilter
Interface MappingFilter

All Superinterfaces:

IDLEntity, MappingFilterOperations, Object, java.io.Serializable

public interface MappingFilter
extends Object, MappingFilterOperations, IDLEntity

The MappingFilter interface defines the behaviors of objects, which encapsulate a sequence of constraint-value pairs, where each value represents a possible setting of a particular property of an event. Note that setting of a particular property is not intended to imply that any contents of the event will be altered as a result of applying a mapping filter, but rather the way a proxy treats the event with respect to a particular property could change. Upon receiving each event, a proxy object with an associated object supporting the MappingFilter interface will invoke the appropriate match operation variant (depending upon whether the event is received in the form of an untyped event, a Structured Event, or a typed event) on the mapping filter object in order to determine how it should modify a particular property value associated with the event to one of the values associated with one of the constraints encapsulated by the mapping filter. Internally, the mapping filter object applies the constraints it encapsulates to the event in order to determine whether or not the event?s property should be modified to one of the values associated with a constraint, or else the default value associated with the mapping filter.

Each instance of an object supporting the MappingFilter interface is typically associated with a specific event property. For instance, in this specification MappingFilter object instances are used to affect the properties of priority and lifetime for events received by a proxy supplier object. Each event received by a proxy object, which has an object supporting the MappingFilter interface associated with it must satisfy at least one of the constraints associated with the MappingFilter object in order to have its property value modified, otherwise the property will remain unchanged. A specific instance supporting the MappingFilter interface typically applies its encapsulated constraints in an order which begins with the best possible property setting (e.g., the highest priority or the longest lifetime), and ends with the worst possible property setting. As soon as a matching constraint is encountered, the associated value is returned as an output parameter and the proxy which invoked the operation proceeds to modify the property of the event to the new value.

The constraint expressions associated with a particular object supporting the MappingFilter interface are expressed as strings which obey the syntax of a particular constraint grammar (i.e., a BNF). 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 MappingFilter interface, they can be attached to proxy objects in the same fashion as the default MappingFilter objects supported by the implementation of the service are, and the channel should be able to use them to potentially affect the properties of events in the same fashion.

The MappingFilter interface supports the operations required to manage the constraint-value pairs associated with an object instance which supports the interface. In addition, the MappingFilter interface supports a readonly attribute which identifies the particular constraint grammar in which the constraints encapsulated by this object have meaning. The MappingFilter interface also supports a readonly attribute which identifies the typecode associated with the datatype of the specific property value it is intended to affect, and another readonly attribute which holds the default value which will be returned as the result of a match operation in cases when the event in question is found to satisfy none of the constraints encapsulated by the mapping filter. Lastly, the MappingFilter interface supports three variants of the operation which will be invoked by an associated proxy object upon receipt of an event, to determine how the property of the event which the target mapping filter object was designed to affect should be modified.

Method Summary

Methods inherited from interface org.omg.CORBA.Object

_create_request, _create_request, _duplicate, _get_domain_managers, _get_interface_def, _get_policy, _hash, _is_a, _is_equivalent, _non_existent, _release, _request, _set_policy_override

Methods inherited from interface org.omg.CosNotifyFilter.MappingFilterOperations

add_mapping_constraints, constraint_grammar, default_value, destroy, get_all_mapping_constraints, get_mapping_constraints, match_structured, match_typed, match, modify_mapping_constraints, remove_all_mapping_constraints, value_type