Abstract:
A system for eliminating redundant notifications to SIP/SIMPLE subscribers, the system including a notification fingerprinter configured to generate a fingerprint from the contents of a SIP/SIMPLE subscriber notification using a predefined fingerprinting method, a fingerprint comparactor configured to compare a fingerprint of a previously-sent notification with a fingerprint of a waiting-to-be-sent notification, and a server configured to send the waiting-to-be-sent notification to the subscriber only if the fingerprints do not match.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to computer networks in general, and more particularly to providing information to networked entities regarding the status of other networked entities. 
       BACKGROUND OF THE INVENTION 
       [0002]    The Session Initiation Protocol (SIP) is a protocol for creating, modifying, and terminating computer network-based communication sessions, such as for an Internet-based telephone call between two or more participants. Since its introduction various enhancements to SIP have been proposed, including the SIP Instant Messaging and Presence Leveraging Extensions (SIMPLE) framework in which one or more network entities, such as computer users, create subscriptions on a server, known as a “presence” server, to receive presence information regarding another network entity, referred to as a “presentity.” When a change in the presentity&#39;s presence information is detected, such as when the presentity “publishes” such a change to the presence server, SIP is used to send a notification to the subscribers including the presentity&#39;s current presence information. 
         [0003]    Further enhancements to SIP/SIMPLE include enabling presentities to limit what presence information subscribers may receive in a notification, as well as enabling subscribers to limit what available presence information they wish to receive in a notification. For example, presentity Joe&#39;s presence information includes elements ABCDE, while Joe limits subscriber Bob to receive only elements BCDE. If a change occurs to any of elements ABCDE, the presence server managing Bob&#39;s subscription will send Joe a notification including elements BCDE. However, if the change is to element A, and Bob previously received a notification including elements BCDE, Bob will receive no new information in the notification, as Bob previously received elements BCDE and does not in any case receive element A. Similarly, if Bob is only interested in elements DE, and sets a notification filter accordingly, if the change is to any of elements ABC, and Bob previously received a notification including elements DE, Bob will receive no new information in the notification, as Bob only ever receives elements DE. In both these examples, the changes to Joe&#39;s presence information caused redundant notifications to be sent to Bob, needlessly consuming processing and bandwidth resources. 
         [0004]    Systems and/or methods for eliminating redundant notifications to SIP/SIMPLE subscribers would therefore be advantageous. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention in embodiments thereof discloses novel systems and methods for eliminating redundant notifications to SIP/SIMPLE subscribers. 
         [0006]    In one aspect of the present invention a system is provided for eliminating redundant notifications to SIP/SIMPLE subscribers, the system including a notification fingerprinter configured to generate a fingerprint from the contents of a SIP/SIMPLE subscriber notification using a predefined fingerprinting method, a fingerprint comparator configured to compare a fingerprint of a previously-sent notification with a fingerprint of a waiting-to-be-sent notification, and a server configured to send the waiting-to-be-sent notification to the subscriber only if the fingerprints do not match. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention in embodiments thereof will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which: 
           [0008]      FIG. 1A  is a simplified illustration of a system for eliminating redundant notifications to SIP/SIMPLE subscribers, constructed and operative in accordance with an embodiment of the present invention; 
           [0009]      FIG. 1B  is a simplified illustration of a system for eliminating redundant notifications to SIP/SIMPLE subscribers, constructed and operative in accordance with an embodiment of the present invention; and 
           [0010]      FIG. 2  is a simplified flowchart illustration of an exemplary method of operation of the system of  FIGS. 1A and 1B , operative in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    The present invention is now described within the context of one or more embodiments, although the description is intended to be illustrative of the invention as a whole, and is not to be construed as limiting the invention to the embodiments shown. It is appreciated that various modifications may occur to those skilled in the art that, while not specifically shown herein, are nevertheless within the true spirit and scope of the invention. 
         [0012]    Reference is now made to  FIG. 1A , which, is a simplified illustration of a system for eliminating redundant notifications to SIP/SIMPLE subscribers, constructed and operative in accordance with an embodiment of the present invention. In the system of  FIG. 1A , a server  100 , such as a computer running a SIP/SIMPLE presence server, sends a notification to a subscriber for a presentity&#39;s presence information  102 . The notification is typically sent in response to server  100  receiving a request to create, renew, or cancel the subscription, or when there is a change in the presence information of the presentity as such information is known to server  100 . 
         [0013]    Server  100  typically includes, or has access to, a notification fingerprinter  104  which generates a fingerprint from the contents of the notification using a predefined fingerprinting method. The fingerprint is generated using any conventional technique, such as by creating a hash value from the notification in accordance with a predefined hash algorithm. The fingerprint is preferably generated such that the probability that two different notifications will have the same fingerprint is below a predefined threshold. One fingerprint may be generated for the entire notification, or alternatively the notification may be split into multiple segments, with a separate fingerprint being created separately for each segment, and an overall fingerprint being formed from the separate fingerprints. The fingerprint is preferably stored in a data store  106 , which may be any computer-readable storage medium, together with an identifier of the subscriber to which the notification is sent, such as a network address, and/or the subscription, such as the SIP session ID of the subscription for which the notification is sent. 
         [0014]    Reference is now made to  FIG. 1B , which, is a simplified illustration of a system for eliminating redundant notifications to SIP/SIMPLE subscribers, constructed and operative in accordance with an embodiment of the present invention. In the system of  FIG. 1B , prior to sending a notification to a subscriber, notification fingerprinter  104  preferably generates a fingerprint from the contents of the notification using the predefined fingerprinting method. Server  100  then retrieves the fingerprint from data store  106  of the notification last sent to the subscriber. Server  100  typically includes, or has access to, a fingerprint comparator  108  which compares the stored fingerprint with the fingerprint generated for the notification waiting to be sent to the subscriber. If the fingerprints match, the notification waiting to be sent may be considered to be a duplicate of the notification last sent to the subscriber, whereupon server  100  preferably does not send the notification to the subscriber. If the fingerprints do not match, the notification waiting to be sent is not the same as the notification last sent to the subscriber, whereupon server  100  sends the notification to the subscriber, and replaces the fingerprint of the previous notification with the fingerprint of the currently sent notification. 
         [0015]    Reference is now made to  FIG. 2 , which is a simplified flowchart illustration of an exemplary method of operation of the system of  FIGS. 1A and 1B , operative in accordance with an embodiment of the invention. In the method of  FIG. 2 , when a notification is sent, such to a subscriber for presence information in a SIP/SIMPLE system, a fingerprint is generated from the contents of the notification as described above, and the fingerprint is stored together with an identifier of the subscriber to which the notification is sent. Prior to sending a subsequent notification to the subscriber, a fingerprint is generated from the contents of the notification using same fingerprinting method as before. The stored fingerprint of the previous notification and the fingerprint of the subsequent notification are then compared. If the fingerprints match, the subsequent notification is not sent to the subscriber. If the fingerprints do not match, the subsequent notification is sent to the subscriber, and the fingerprint of the previous notification is replaced with the fingerprint of the currently sent notification. 
         [0016]    Any of the elements shown in  FIGS. 1A and 1B  and method steps shown in  FIG. 2  are preferably implemented in computer hardware and/or in computer software embodied in a computer-readable medium. 
         [0017]    It is appreciated that one or more of the steps of any of the methods described herein may be omitted or carried out in a different order than that shown, without departing from the true spirit and scope of the invention. 
         [0018]    While the methods and apparatus disclosed herein may or may not have been described with reference to specific computer hardware or software, it is appreciated that the methods and apparatus described herein may be readily implemented in computer hardware or software using conventional techniques.