RESOURCE TRACKING

• US 20100088300A1
• Filed: 10/06/2008
• Published: 04/08/2010
• Est. Priority Date: 10/06/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Mody, Viraj B., Steere, David C., Kleinpeter, Thomas W., Zintel, William Michael, Copeland, Bruce W., Adya, Atul, Gbadegesin, Abolade
• Granted Patent: US 8,335,762 B2
• Time in Patent Office: Days
• US Class Current: 707/705
• CPC Class Codes: G06F 16/24568 Data stream processing; Continuous queries
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes

Abstract

Clients may subscribe to resources for the purpose of receiving notifications of changes in the resource (e.g., a file is added to a shared folder). Storing subscriptions within persistent storage provides data security in the event of a service failure, at the cost of high latency in accessing subscription data. An efficient method for tracking a resource is provided herein. A subscription service creates subscriptions and monitors resources for a client. Upon a subscribed resource change, a notification service stores a notification of the change into a queue associated with the client. Efficient resource tracking is achieved because notification and subscription data is stored in low latency soft memory. The notification service is configured to detect a failure in the notification service and/or subscription service. In the event a service fails, the client provides a recovery mechanism by resubscribing to resources the client is interested in.

Claims

1. A system for tracking a resource comprising:

a notification service configured to;

create a queue;

receive information regarding a queue ownership; and

store a notification of the information within the queue; and

a subscription service configured to;

create a subscription regarding a resource to be monitored for changes; and

distribute information regarding a resource change to the notification service.

2. The system of claim 1, information regarding the queue ownership comprising at least one of:

a resource change;

a peer-to-peer invite; and

a service failure.

3. The system of claim 1, the subscription comprising at least one of:

a reference to a queue that is to be notified when the resource changes; and

a URL associated with the resource.

4. The system of claim 3, the notification service configured to create one or more queues and the subscription service configured to instruct the notification service into which queue to store a notification regarding a resource change.

5. The system of claim 1, comprising:

a client configured to store information regarding one or more resources to be monitored for changes.

6. The system of claim 5, the client configured to periodically send a request to the notification service comprising at least one of:

an instruction to create a queue;

an instruction to extract a notification from the queue;

an identifier corresponding to a notification service identifier; and

a queue identifier corresponding to a queue associated with the client.

7. The system of claim 5, the client configured to send a request to the subscription service, the request comprising at least one of:

a resource to be monitored for changes; and

a queue identifier associated with a queue that is to be notified of changes to the resource.

8. The system of claim 6, the notification service configured to perform a notification service failure check comprising:

extracting the identifier from the request received from the client;

determining a mismatch of the identifier with a current notification service identifier; and

upon determining a mismatch;

create a new queue comprising a new queue identifier; and

store a notification into the new queue comprising at least one of the following;

a message that the notification service failed;

an instruction to resubscribe to one or more resources;

the new queue identifier; and

the current notification service identifier.

9. The system of claim 1, the notification service configured to:

upon receiving a message that the subscription service failed, store a notification in the queue, the notification comprising a message that the subscription service failed and an instruction to resubscribe to one or more resources.

10. The system of claim 1, the subscription service configured to associate a time to live value with a resource, wherein if the time to live value falls below a predetermined threshold, then the resource is removed from the subscription service.

11. The system of claim 1, the queue stored in volatile memory and the subscription stored in volatile memory.

12. A method for tracking a resource comprising:

obtaining a subscription regarding a resource to be monitored for changes;

providing information regarding a change in status of the resource to a notification service;

specifying to the notification service which of a plurality of queues into which a notification regarding the change in status of the resource is to be stored;

storing into the specified queue, with the notification service, the notification regarding the change in status of the resource; and

upon receiving a request from a client, extracting the notification from the specified queue corresponding to the client.

13. The method of claim 12, the receiving a request from a client comprising:

extracting an identifier, from the request, identifying a notification service;

extracting a queue identifier, from the request, identifying a queue associated with the client;

comparing the identifier with a current notification service identifier of the notification service; and

upon determining the identifier from the request and the current notification service identifier match, extracting one or more notifications from a queue, corresponding to the queue identifier, to the client.

14. The method of claim 13, comprising:

upon determining the notification service identifier from the request and the current notification service identifier do not match;

creating a new queue associated with a new queue identifier; and

storing a notification into the new queue, the notification comprising at least one of the following;

a message that the notification service failed;

an instruction to resubscribe to one or more resources;

the new queue identifier; and

the current notification service identifier.

15. The method of claim 14, comprising:

extracting, with the client, the notification within the new queue;

storing the new queue identifier and the current notification service identifier within the client; and

sending a request to a subscription service to resubscribe to a resource to be monitored, the request comprising the new queue identifier and the resubscribed to resource.

16. The method of claim 12, comprising:

receiving, with the notification service, a message that a subscription service hosting one or more subscriptions failed; and

storing a notification into one or more queues associated with the failed subscription service, the notification comprising information regarding the subscription service failure and an instruction to resubscribe to one or more resources.

17. The method of claim 12, comprising at least one of:

associating a time to live with a resource, wherein if a number of subscriptions fall below a predetermined threshold, then the resource is removed from a subscription service; and

associating a time to live with a client, wherein if a client times out after a predetermined time, the client and corresponding queue and subscriptions are removed.

18. The method of claim 12, comprising:

storing the queue in volatile memory;

storing the notification in volatile memory; and

storing the subscription in volatile memory.

19. A system for providing a notification service comprising:

a notification service, located on one or more servers, configured to;

provide a notification within a queue stored in volatile memory to a client, the notification regarding updates to a resource subscribed to by the client; and

provide a notification within the queue, the notification instructing the client to resubscribe to a resource based upon a state loss; and

a subscription service, located on one or more servers, configured to;

create a subscription in volatile memory regarding a resource to be monitored for changes and a client to be notified of a resource change; and

upon receiving a message that the resource has changed, sending a request to the notification service to store a notification into a queue corresponding to the client that is subscribed to resource.

20. The system of claim 19, comprising:

one or more clients configured to;

store information regarding one or more subscribed services;

request the notification service to create a queue corresponding to the client;

request the subscription service to create a subscription to a resource; and

request an extraction of a notification from the queue.