Mechanism for dynamically associating a service dependent representation with objects at run time

• US 6,044,224 A
• Filed: 06/26/1996
• Issued: 03/28/2000
• Est. Priority Date: 06/26/1996
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Lim, Swee Boon, Kessler, Peter B., Radia, Sanjay R.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): Smithers, Matthew
• Application Number:
  US08/670,682
• Time in Patent Office: 1,371 Days
• Field of Search: 395/710, 395/600, 395/685, 395/682, 395/200.33, 395/701, 395/200.51, 395/671
• US Class Current: 717/162
• CPC Class Codes: G06F 9/465 Distributed object oriented systems remote method invocation [RMI] G06F9/548

Abstract

A data structure for dynamically associating a service dependent representation with a servant object at run time is used in a distributed object computing system that incorporates subcontracts. Subcontracts supply different functionalities to objects. The data structure exists before run time, and is used at run time to perform the dynamic association. An arrangement also exists at run time. The structure comprises a service representation class representing a single subcontract, a servant base class associated with servant objects created at run time, and a linking mechanism to form a run time link between the server rep class and a servant object at run time. The server rep class provides functionality unique to a subcontract. At run time, servant objects are instantiated from the servant base class or a more derived class. The servant object uses the functionality provided by a subcontract by way of the linking mechanism. An arrangement exists at run time for dynamically linking a servant object to a subcontract. Included are a servant object, a server rep object, and a pointer from the servant object to the server rep object. Methods and apparatus allow a servant object itself to initiate calls to deactivate itself, to determine remaining references to itself, to revoke itself, and to get an object reference for itself. A method creates a servant object that includes the above data structures and ability to call these functions.

Claims

1. An association mechanism data structure for dynamically associating a service representation object with a servant object at run time in a distributed object computing system, said distributed object computing system incorporating a plurality of groups of object services, the association mechanism data structure being embodied in a computer-readable medium and comprising:

at least one service representation class representing a single one of the groups of object services, the service representation class arranged to provide functionality unique to said single one of the groups of object services via an instantiated service representation object at runtime;

at last one servant base class arranged to be associated with servant objects that are created at run time; and

a linking mechanism arranged to form a run time link between the service representation object and a selected one of said servant objects at run time such that the servant object may use the functionality provided by said single one of the groups of object services by way of the service representation object.

2. An association mechanism data structure as recited in claim 1 wherein at run time the service representation object associated with the service representation class is created and the run time link includes a location indicator from the selected servant object to the service representation object.

3. An association mechanism data structure as recited in claim 1 wherein the service representation class includes a method suitable for deactivating a servant object, revoking a servant object, or determining whether there are currently references to a servant object.

4. An association mechanism data structure as recited in claim 3 wherein the service representation class further includes a method suitable for getting an object reference for a servant object.

5. A rum-time arrangement data structure embodied in a computer-readable medium for use in a distributed object computing system, said distributed object computing system incorporating a plurality of groups of object services, the run-time arrangement comprising:

a servant object that takes the form of an instance of a distributed object;

a service representation object representing a single one of the groups of object services, the service representation object being arranged to provide functionality unique to said single one of the groups of object services by way of a service representation class; and

a link between the service representation object and the servant object that permits the servant object to access the functionalities provided by the service representation class by way of the service representation object.

6. An arrangement data structure as recited in claim 5 wherein the link includes a location indicator from the servant object to the service representation object.

7. An arrangement as recited in claim 5 wherein the service representation object provides access to methods suitable for deactivating the servant object, revoking the servant object, or determining whether there are currently references to the servant object, said methods thereby being accessible by the servant object.

8. An arrangement as recited in claim 7 wherein the service representation object further provides access to a method suitable for getting an object reference for the servant object that is accessible by the servant object.

9. A computer-implemented method of creating a distributed servant object for use in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, the method comprising:

receiving a servant class name and an object adaptor delegate identifying a single one of the groups of object services;

instantiating a servant object corresponding to the received servant class name;

calling a create method of the object adaptor delegate in order to produce a service representation object arranged to provide functionality unique to said single one of the groups of object services identified by said object adaptor delegate; and

associating the produced service representation object with the servant object such that the servant object may use the functionality provided by said single one of the groups of object services available through the service representation object.

10. A method as recited in claim 9 wherein the create method comprises:

creating an object key that uniquely identifies the servant object within a process;

storing the object key in a lookup table in association with a reference to the servant object; and

creating the service representation object that corresponds to said single one of the groups of object services identified by the object adaptor delegate.

11. A method as recited in claim 9 wherein the object adaptor delegate identifies a single one of the groups of object services by reference to a received object key having a subcontract identifier and the create method comprises

creating the service representation object corresponding to said single one of the groups of object services identified by the subcontract identifier.

12. A computer-implemented method of revoking a distributed servant object in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, the method comprising:

calling a servant revoke method associated with the servant object, the servant revoke method being called by the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a service representation revoke method associated with the service representation object via said link; and

revoking the servant object by way of the called service representation revoke method in a manner consistent with the single one of the groups of object services.

13. A computer-implemented method of creating an object reference of a servant object for use by a client in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, the method comprising:

receiving a get object reference request for a specified super class of a servant object, the request originating from the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a get object reference method associated with the service representation object and implementing said get object reference method in a manner consistent with the single one of the groups of object services;

creating a fat pointer to the servant object, the fat pointer being created by the get object reference method; and

widening the fat pointer in order to associate it with the specified super class.

14. A computer-implemented method of deactivating a distributed servant object in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, the method comprising:

calling a servant deactivate method associated with the servant object, the servant deactivate method being called by the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a service representation deactivate method associated with the service representation object; and

deactivating the servant object by way of the called service representation deactivate method in a manner consistent with the single one of the groups of object services.

15. A computer-implemented method of deactivating a distributed servant object as recited in claim 14 further comprising:

creating a call back closure for the servant object;

passing the call back closure to the service representation object together with the call to the service representation deactivate method;

determining whether the servant object may be deactivated; and

when it is determined that the servant object may be deactivated, executing the call back closure.

16. A computer implemented method of deactivating a distributed servant object as recited in claim 15 further comprising

calling a servant deactivate done method associated with the servant object in order to deactivate the servant object.

17. A computer apparatus comprising:

a processing unit;

an input/output device coupled to said processing unit; and

a storage device in communication with said processing unit, the storage device including an association mechanism data structure for dynamically associating a service representation with a servant object at run time in a distributed object computing system, said distributed object computing system incorporating a plurality of groups of object services, the association mechanism data structure being embodied in a computer-readable medium and comprising

at least one service representation class representing a single one of the groups of object services, the service representation class arranged to provide functionality unique to said single one of the groups of object services via an instantiated service representation object at runtime,

at least one servant base class arranged to be associated with servant objects that are created at run time, and

a linking mechanism arranged to form a run time link between the service representation class and a selected one of said servant objects at run time such that the servant object may use the functionality provided by said single one of the groups of object services by way of the service representation object.

18. A computer program product comprising a computer-usable medium having computer-readable program code embodied thereon for creating a distributed servant object for use in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, said computer program product comprising computer-readable program code for effecting the following within a computer system:

receiving a servant class name and an object adaptor delegate identifying a single one of the groups of object services;

instantiating a servant object corresponding to the received servant class name;

calling a create method of the object adaptor delegate in order to produce a service representation object arranged to provide functionality unique to said single one of the groups of object services identified by said object adaptor delegate; and

associating the produced service representation object with the servant object such that the servant object may use the functionality provided by said single one of the groups of object services available through the service representation object.

19. A computer program product as recited in claim 18 wherein the create method comprises:

creating an object key that uniquely identifies the servant object within a process;

storing the object key in a lookup table in association with a reference to the servant object; and

creating the service representation object that corresponds to said single one of the groups of object services identified by the object adaptor delegate.

20. A computer program product as recited in claim 18 wherein the object adaptor delegate identifies a single one of the groups of object services by reference to a received object key having a subcontract identifier and the create method comprises

creating the service representation object corresponding to said single one of the groups of object services identified by the subcontract identifier.

21. A computer program product comprising a computer-usable medium having computer-readable program code embodied thereon for revoking a distributed servant object in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, said computer program product comprising computer-readable program code for effecting the following within a computer system:

calling a servant revoke method associated with the servant object, the servant revoke method being called by the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a service representation revoke method associated with the service representation object via said link; and

revoking the servant object by way of the called service representation revoke method in a manner consistent with the single one of the groups of object services.

22. A computer program product comprising a computer-usable medium having computer-readable program code embodied thereon for creating an object reference of a servant object for use by a client in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, said computer program product comprising computer-readable program code for effecting the following within a computer system:

receiving a get object reference request for a specified super class of a servant object, the request originating from the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a get object reference method associated with the service representation object and implementing said get object reference method in a manner consistent with the single one of the groups of object services;

creating a fat pointer to the servant object, the fat pointer being created by the get object reference method; and

widening the fat pointer in order to associate it with the specified super class.

23. A computer program product comprising a computer-usable medium having computer-readable program code embodied thereon for deactivating a distributed servant object in a distributed object computing system, the distributed object computing system providing groups of object services for use in managing distributed objects, said computer program product comprising computer-readable program code for effecting the following within a computer system:

calling a servant deactivate method associated with the servant object, the servant deactivate method being called by the servant object;

identifying a service representation object associated with the servant object, the service representation object being associated with said servant object via a link and being arranged to provide functionality unique to a single one of the groups of object services;

calling a service representation deactivate method associated with the service representation object; and

deactivating the servant object by way of the called service representation deactivate method in a manner consistent with the single one of the groups of object services.

24. A computer program product for deactivating a distributed servant object as recited in claim 23 further comprising program code for effecting:

creating a call back closure for the servant object;

passing the call back closure to the service representation object together with the call to the service representation deactivate method;

determining whether the servant object may be deactivated; and

when it is determined that the servant object may be deactivated, executing the call back closure.

25. A computer program product for deactivating a distributed servant object as recited in claim 24 further comprising program code for effecting calling a servant deactivate done method associated with the servant object in order to deactivate the servant object.