Abstract:
Networked systems may participate in data sharing sessions in which previously transmitted data is cached. When a system learns that it is about to receive data that was cached previously, the system can recall the cached data instead of receiving a new data download.

Description:
BACKGROUND  
         [0001]    This invention relates to multiparty communications over computer networks.  
           [0002]    In on-line meeting software, a presenter can distribute various images via a communications network to other meeting participants such that each participant is simultaneously viewing the same image on his or her computer. By way of example, the image may be a slide created by presentation graphics software. Meeting participants may then discuss a commonly displayed image by, for example, on-screen text messaging or “chat” windows, video phones or conventional telephone conference calling.  
           [0003]    With conventional systems, if the meeting participants wish to return to a previously sent slide for further discussion, the image must be resent from the meeting presenter&#39;s computer to each participant&#39;s computer. This is a time-consuming process inasmuch as images typically comprise large amounts of data and the data must be sent over communications channels having finite bandwidths.  
           [0004]    Thus, there is a need for a way to facilitate on-line conferences.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 shows networked, processor-based systems comprising one embodiment of the present invention;  
         [0006]    [0006]FIG. 2 is a software flow chart for one embodiment of the invention;  
         [0007]    [0007]FIG. 3 is a flow chart for another embodiment of the invention; and  
         [0008]    [0008]FIG. 4 is a flow chart for another embodiment of the invention.  
         [0009]    [0009]FIG. 5 is a flow chart for another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0010]    A network  32  includes at least two client processor-based systems  8 , as shown in FIG. 1. The network  32  may be a wired or wireless local area network (LAN) in one embodiment of the present invention. Each system  8  may include a processor  38  coupled to a display  34  and a storage device  42 . The processor-based system  8   a  may be used by the presenter in an on-line meeting or conference set up between a presenter and one or more participants. The system  8   b  may be used by a participant.  
         [0011]    Both systems  8  may be personal computers in one embodiment and the storage  42  may be, for example, a magnetic media disk drive with associated disk controllers or solid-state memory such as random access memory (RAM). The system  8   b  storage  42  may store software  40  for enabling the processor  38  to participate in a network presentation as well as the data  30  to be presented. The system  8   a  storage  42  may store software  50  for implementing a network presentation.  
         [0012]    The software  40  may operate as part of or work with on-line conferencing software. An example of on-line conferencing software is NetMeeting software from Microsoft Corporation, Redmond, Wash.  
         [0013]    An on-line meeting may be set up between a presenter system  8   a  and one or more participant systems  8   b  by establishing communications over a network  32 , as indicated at block  10  of FIG. 2. The presenter&#39;s system  8   a  may send data to each of the participant systems  8   b . The shared data may be, for example, a series of images or frames. The presenter&#39;s system  8   a  may send each image when the presenter desires to change the image displayed for viewing by the participants.  
         [0014]    The presenter may have created the images with presentation graphics software and the images may comprise slides. Each slide may have a unique identifier that may be, for example, a file attribute of the data comprising the image.  
         [0015]    During the course of the on-line meeting, the presenter&#39;s system  8   a  may send data relating to a slide to participant systems  8   b , as indicated at block  14 . As shown at diamond  18 , a participant&#39;s system  8   b  may determine, for example by testing the slide identifier, whether the slide being sent by the presenter&#39;s system  8   a  is a new slide or a previously-sent slide. Multitasking techniques may be employed by a participant&#39;s system  8   a  to compare the identifier with the identifiers of cached images while the session is still in progress.  
         [0016]    If the slide is a previously-sent slide, it may be available in a local cache of slides and may be retrieved from the cache, as indicated at block  22 . The cached slide may be displayed, as indicated at block  26 , on the participant&#39;s processor-based system  8   b.    
         [0017]    If the slide is in the local cache, the transmitted image data may be directed to a “bit bucket” while the cached slide is retrieved and displayed as indicated at blocks  22  and  26 , respectively. A bit bucket is an imaging location into which data can be discarded.  
         [0018]    If, however, the slide is not in the cache, the slide may be downloaded from the presenter&#39;s system  8   a  over the network  32 , as indicated at block  20 , and subsequently cached and displayed, as indicated at blocks  24  and  26 , respectively. In this way, participants who join the meeting late may download a slide previously sent to other participants without delaying the image viewing by the earlier-joining participants whose systems may have the slide in their local caches.  
         [0019]    Inasmuch as data can typically be retrieved from a local cache more quickly than it can be downloaded via a network  32 , participants in an on-line meeting can save time whenever the presenter returns to a previously-sent slide for discussion that is already available in a participant&#39;s system  8   b.    
         [0020]    If the meeting is concluded, as indicated at the right branch of diamond  28 , the participant system  8   b  may disconnect from the session as indicated at block  30 . The meeting may be over when an indicating signal is sent from the system  8   a  to the system  8   b  in one embodiment. If the meeting is not over, as indicated by the lower branch of diamond  28 , the participant&#39;s system  8   b  may query the presenter to determine whether the presenter has changed his or her system to edit mode, as indicated at diamond  12 .  
         [0021]    Graphics generating programs may have multiple modes of operation. For example, a software package for presentation graphics may have an editing mode wherein slides are created and modified and a presentation mode or “slide show” mode wherein a predetermined sequence of slides is displayed seriatim.  
         [0022]    The presenter may desire to edit the presentation graphics during the course of an on-line meeting. In such a situation, the presenter may change the state of the system  8   a  from a presentation mode to an editing mode. If the presenter alters one or more images on his or her system, one or more images which may have been cached by the participants&#39; systems may no longer correspond to the images stored by the presenter&#39;s system  8   a  even though the images may have the same identifier. In such an instance, a participant system  8   b  local cache is “stale” and should be “flushed”, as indicated at block  19 —i.e., cleared from the data storage sub-system of a participant&#39;s system as though no images were cached.  
         [0023]    The presenter&#39;s system  8   a  may broadcast a message or code that indicates to all participant systems  8   b  that the presenter has switched his or her system to editing mode. In response, each participant&#39;s system  8   b  local cache may be flushed, as indicated at block  19 . Alternatively, each participant system  8   b  may query the presenter&#39;s system  8   a  regarding its mode, as indicated at diamond  12 . If the presenter&#39;s system  8   a  responds that it is in edit mode, the participant&#39;s system  8   b  may flush its local cache, as indicated at block  19 . In yet another alternative, the presenter&#39;s system  8   a  may indicate which image or images have been altered and, in response, the participant&#39;s system  8   b  may flush only those images from its local cache.  
         [0024]    In this way, a meeting participant&#39;s system  8   b  may build a local cache of slides during the course of an online meeting as the meeting presenter&#39;s system  8   a  sends individual slides, seriatim. During a meeting, because a participant&#39;s system  8   b  is able to retrieve previously-sent slides from a local cache, the images may be displayed more quickly than if the image data is again downloaded from a network  32 .  
         [0025]    In another embodiment, an on-line meeting presenter&#39;s system may send a slide identifier (but initially not image data) to meeting participant system  8   b , as indicated at block  15  of FIG. 3. The presenter system  8   a  may then wait for a request from a participant system  8   b  for the image data comprising the slide.  
         [0026]    As indicated at block  17  of FIG. 3, a meeting participant system  8   b  may determine from the slide identifier whether the slide exists in its local cache. If the slide is found in the local cache, it may be retrieved from the cache  22  and displayed, as indicated at blocks  22  and  26 , respectively.  
         [0027]    If, however, the image data comprising the slide is not found in the local cache, as indicated at the right branch of diamond  17 , the participant system  8   b  may request the slide from the presenter system  8   a , as indicated at block  21 . The presenter system  8   a  may, in response, send the requested slide, as indicated at block  16 , which data may then be stored by the participant system  8   b  in its local cache and displayed, as indicated at blocks  24  and  26 , respectively.  
         [0028]    In this embodiment, the presenter system  8   a  need not send the image data comprising the slide if all participant systems  8   b  already have the slide in their local caches i.e., if no participant system  8   b  requests a download of the image data. In this way, both time and network resources may be conserved.  
         [0029]    In yet another embodiment, cache-participants may receive a download of a slide during the course of an online meeting and subsequently determine whether a cached version differs from the downloaded version. In the meantime, the cached version may be displayed. The presenter&#39;s system  8   a  may send data relating to a slide to participant systems  8   b , as indicated at block  14  of FIG. 5. A participant&#39;s system  8   b  may extract a slide identifier from this data as shown at block  15   a . As shown at diamond  17 , a participant&#39;s system  8   b  may then determine, for example by testing the slide identifier, whether the slide being sent by the presenter&#39;s system  8   a  has the same identifier as a previously-sent slide. Multitasking techniques may be employed by a participant&#39;s system  8   a  to compare the identifier with the identifiers of cached images while the session is still in progress.  
         [0030]    If the slide identifier corresponds with that of a previously-sent slide, it may be available in a local cache of slides and may be retrieved from the cache, as indicated at block  22 . The cached slide may be displayed, as indicated at block  26   a , on the participant&#39;s processor-based system  8   b  along with a warning to the viewer that the slide may not correspond with that of the presenter&#39;s system.  
         [0031]    As indicated at block  20 , the download of image data may be completed by the participant&#39;s system. As indicated at diamond  23 , the just-downloaded image data may then be compared to the cached image data having the same slide identifier to determine whether there has been any change in the data. If no change is detected, the warning on the display may be removed as indicated at block  26   c . If, however, a change is found, the just-downloaded data may be stored in the cache replacing the previously stored data having the same identifier, as indicated at block  24   a . The displayed image may then be updated using the new data and the display warning removed as indicated at blocks  26   b  and  26   c , respectively. If the changes in the image data are minimal, display techniques may be employed to smoothly “morph” the image from the previous version to the more recent one.  
         [0032]    If, however, the slide is not in the cache as indicated by the left branch of diamond  17 , the slide may be downloaded from the presenter&#39;s system  8   a  over the network  32 , as indicated at block  20   a , and subsequently cached and displayed, as indicated at blocks  24  and  26 , respectively.  
         [0033]    In this way, the speed of a cache-based system may be realized whenever the meeting participants return to a previously sent slide even if the image must subsequently be modified due to a change in the image by the presenter.  
         [0034]    Referring to FIG. 4, the software  50  on the presenter system  8   a  may implement the caching protocol in conjunction with the participant systems  8   b . Initially, the presenter system  8   a  establishes the network meeting as indicated in block  52 . Information may be sent to the participants concerning each slide as indicated in block  54 . In some embodiments, this may include the initial download of a portion of the slide. In other embodiments, only an identifier for the slide may be provided. If only an identifier is provided, then the information is not sent until the participant indicates that it actually wants the download. If only a portion of the slide is provided, the same protocol may be utilized or, the information may be transmitted even if the participant determines that it will not receive the information.  
         [0035]    If the download is requested as determined in diamond  56 , the data may be sent as indicated in diamond  58 .  
         [0036]    In another embodiment, the network  32  may be the Internet. In such case, the systems  8  may communicate and send slides or other data over the Internet.  
         [0037]    While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.