DOFSystembeginQuery Method (DOFObjectID, DOFInterfaceID, DOFSystemQueryOperationListener)OpenDOF Object Access Library
Used by a Requestor to begin an asynchronous query with an indefinate duration for the availability of objects which provide interfaces that match the specified query.

Namespace: org.opendof.core.oal
Assembly: dof-oal (in dof-oal.dll) Version: 7.0.1.2
Syntax
C#
Copy
public DOFOperationQuery beginQuery(
	DOFObjectID oid,
	DOFInterfaceID iid,
	DOFSystemQueryOperationListener operationListener
)

Parameters

oid
Type: org.opendof.core.oalDOFObjectID
Object ID to match. May be null.
iid
Type: org.opendof.core.oalDOFInterfaceID
Interface ID to match. May be null.
operationListener
Type: org.opendof.core.oalDOFSystemQueryOperationListener
The operationListener for receiving asynchronous notification. This must not be null, or no notifications can be received.

Return Value

Type: DOFOperationQuery
The query operation that can be used to cancel the query. Will not be null.
Remarks
Used by a Requestor to begin an asynchronous query with an indefinate duration for the availability of objects which provide interfaces that match the specified query.

NOTE: An application must first express interest by calling beginInterest(DOFObjectID, DOFInterestLevel) . Interest goes out on the network and looks for matching providers. query, on the other hand, searches through the local set of known providers (those found through interest).

  • If oid and iid are null then the query matches all provides compatible with the system.
  • If only the oid is null then the query matches any object providing the specified interface
  • If only the iid is null then the query matches the given object providing any interface.
  • If both the oid and iid are specified the query matches only the specified object providing the specified interface.
See Also

Reference

DOFSystem Class
beginQuery Overload
org.opendof.core.oal Namespace