Object connectivity through loosely coupled publish and subscribe events

• US 20050044554A1
• Filed: 09/29/2004
• Published: 02/24/2005
• Est. Priority Date: 02/23/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: McCrady, Donald J., Pollack, Seth B., Dumitru, Donald W., Swartz, Stephen T., Hinson, Gerald L., Al-Ghosein, Mohsen
• Granted Patent: US 7,478,405 B2
• Time in Patent Office: Days
• US Class Current: 719/318
• CPC Class Codes: G06F 2209/543 Local
• CPC Class Codes: G06F 9/4488 Object-oriented
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications

Abstract

An object-based event communications system supplies an event distribution object having an outgoing-from-publisher event interface and associated with unique identifiers defined for a publisher that is programmed to fire events by calling a method on the event distribution object'"'"'s outgoing-from-publisher event interface. The event communications system stores subscriptions of subscriber objects to methods of the outgoing-from-publisher event interface. On receiving a call from a publisher to its outgoing-from-publisher interface methods, the event distribution object multi-casts calls to counterpart methods of subscriber objects that have stored subscriptions to the respective outgoing-from-publisher interface methods.

Claims

1. A computer-readable storage medium having computer-executable program code stored thereon to implement an object-oriented event communications model for distributing events from a publisher to any subscribers of the events, where a subscriber exposes an outgoing event interface that receives events as calls to methods of the outgoing event interface, the program code comprising:

code operative to manage a plurality of subscriptions, where a subscription associates an event to the subscriber; and

event distribution code operative in response to issuance of the event so as to retrieve the subscription and issue a method call to the subscriber'"'"'s outgoing event interface to thereby distribute the event to the subscriber associated via the subscription with the event;

wherein a deactivated subscriber is activated by said event distribution code before the method call is issued.

2. The computer-readable storage medium of claim 1, wherein the event distribution code comprises an object external to both the publisher and any subscribers of the event.

3. The computer-readable storage medium of claim 1, wherein an event object encapsulates the event distribution code.

4. The computer-readable storage medium of claim 3, wherein an interface exposed by the event object is identically defined as an interface exposed by a subscriber.

5. The computer-readable storage medium of claim 4, wherein an event object comprises code associating an event to a subscriber.

6. The computer-readable storage medium of claim 1, wherein the code operative to manage a plurality of subscriptions includes at least a subscription object that comprises an event class identifier, an event method identifier, and a subscriber reference.

7. The computer-readable medium of claim 6 wherein the event method identifier is a name of a method in an interface subscribed to by a subscriber.

8. The computer-readable medium of claim 6 wherein the subscriber reference is a persistent reference.

9. The computer-readable medium of claim 6 wherein the subscriber reference is an interface identifier of an instance of a subscriber.

13. The method of claim 1, wherein managing a plurality of subscriptions includes managing at least a subscription object that comprises an event class identifier, an event method identifier, and a subscriber reference.

14. The method of claim 13 wherein the event method identifier is a name of a method in an interface subscribed to by a subscriber.

15. The method of claim 13 wherein the subscriber reference is a persistent reference.

16. The method of claim 13 wherein the subscriber reference is an interface identifier of an instance of a subscriber.

19. The computer-readable data storage medium of claim 8, wherein the datum identifying the subscriber object is a class identifier associated with a class of the subscriber object.

20. The computer-readable data storage medium of claim 8, wherein the datum identifying the subscriber object is an interface pointer linking to an interface exposed by the subscriber object.

10. A method of distributing events from a publisher object to subscriber objects, where subscriber objects expose an outgoing event interface that receives events as calls to methods of the outgoing event interface, the method comprising:

managing a plurality of subscriptions, where a subscription associates an event object to a subscriber object;

retrieving a reference to a subscriber object in response to issuance of an event; and

issuing a method call to a retrieved subscriber'"'"'s outgoing event interface to thereby distribute an event to the subscriber object associated via the subscription with the event object;

wherein a deactivated subscriber is activated before the method call is issued to a retrieved subscriber'"'"'s outgoing interface.

11. The method of claim 10, wherein an interface exposed by an event object is identically defined as an interface exposed by a subscriber object.

12. The method of claim 10, wherein associating an event to a subscriber comprises associating an event object with subscriber objects.

17. An object-oriented event communications system for distributing events from publishers to subscribers of the events, where a subscriber exposes an outgoing event interface that receives events as calls to methods of the outgoing event interface, the system comprising:

networked computer devices; and

a distributed application comprising,

subscription management code, operative to manage a plurality of subscriptions, where a subscription associates an event to the subscriber, and

event distribution code operative response to issuance of the event so as to retrieve the subscription and issue a method call to the subscriber'"'"'s outgoing event interface to thereby distribute the event to the subscriber associated via the subscription with the event;

wherein a deactivated subscriber is activated by said event distribution code before the method call is issued.

18. A computer-readable data storage medium having stored thereon a subscription data structure representing a relationship of a subscriber object to a subscribeable outgoing-event interface method callable from a publisher to issue an event, the subscription comprising:

a datum identifying the subscribeable outgoing-event interface method; and

a datum identifying the subscriber object;

whereby the subscription links calls made on the subscribeable outgoing-event interface method to the subscriber object and the subscription is programmatically requested by other than the subscriber object.