Towards Good Web Conferencing System Design for Ubi
Contents
1. and insert at the middle of the conference session his own responses And for later reviewers the last student s interactions are presented just like other students though some notation may be added to indicate this is a make up recording segment 4 3 Anonymity In many scenarios e g sales presentation participants of a conference are strangers to each other Though they will authenticate themselves they may not want others sometimes even the presenter to know that they are in the session Some users may want to hide themselves initially and then show up when they have some questions As far as we observe no existing system deals with this requirement 4 4 Improved Video Conferencing Capability Because of the high bandwidth requirement for the video channel most existing WCSs take video as an add on component that is normally not activated However face to face contact has always been a very important factor in human communication as facial expressions and body languages often tell more than words In addition as pointed out in a recent survey conducted by RoperRAW 18 people tend to be more focused in a face to face meeting while they may do other work such as checking emails or surfing the Internet if no video image is being captured To increase meeting marketing effectiveness providing better video quality is important for next generation WCSs As the last mile bandwidth grows higher and as new video coding st2. input output peripherals and communication networks Example software utilities include presentations web co browsing whiteboard sharing application desktop sharing file transfer text chatting instant messaging audio video communication polling and session recording playback Figure 1 is a screenshot of Centra 2 a WCS on the market from its user manual Various conferencing systems e g 1 2 5 6 7 8 9 10 19 have been on the market for many years But their importance was not fully appreciated until the down cycle of the U S economy in 2000 and the tragic event of 9 11 As more users had gone through the learning curve they started to realize the convenience and power of WCSs Specifically WCSs are easier to set up and normally cheaper than conventional video conferencing system 13 In addition WCSs do not require dedicated ISDN lines Compared with audio conferencing systems WCSs allow people to see each other which is especially important during the initial meetings Furthermore WCSs are better than both video and audio conferencing in that they support easy data collaboration e g application sharing and presentation viewing According to Frost amp Sullivan 7 the worldwide WCS market stood at 472 1 million in 2003 and is expected to reach 3 02 billion by 2010 Note that WCSs are different from conventional Instant Messaging IM systems such as Yahoo Messenger 20 in that IM systems prima
3. he can review the existing posts and take his time to check related information and organize his thoughts Then he may add his comments into the discussion thread by adding new slides notes whiteboard drawings a few web links or even a piece of audio video recordings The updates to the thread will trigger alert notification to all interested parties who may be offline temporarily When a brilliant idea suddenly strikes someone he does not have to call for an emergency meeting but only needs to join the asynchronous meeting and presents his thoughts right away 4 2 Smart Recording and Playback Recording and playback of web conferences is still an under studied field We propose four directions where improved user experience may be achieved Event based Recording Playback Almost all existing systems use video based recording of what the on site participants have seen and heard The file size is normally very large yet the video audio quality is generally not satisfactory Considering the fact that the state of the recording session evolves at each user interaction event a past conference session can be completely reconstructed by simulating the original participants interactions events Specifically all the data files e g PowerPoint slides word documents etc and all the user interactions that change the state of the conference session e g document navigation annotation whiteboard strokes session join leav
4. JPEG images based on how much bandwidth they have and how large their screen sizes are Note that this customizability may seem contradictory to the principle of ease of use But in fact they are talking about two different dimensions Customizability refers to the process of setting up the WCS while ease of use refers to the process of using the WCS Of course the customization step itself can be made easy to use too In addition ease of use is more desired for novice users and as they become more familiar and experienced with the system customization will become important for them Based on our observation it also a good idea to for WCSs to provide several sets of predefined composition of the functionalities and parameter settings based on the typical user scenarios 3 3 Reliability No one wants to use a system that may crash during an important meeting Because a WCS is in fact a composite session of several distributed applications they are more vulnerable than ordinary systems In such a situation system designers need to take the following two principles into consideration 3 3 1 Independent Service Component When a fault occurs it normally comes from one particular function Therefore if different facilities are as loosely coupled as possible they may still work well when one or more facilities fail For example in many existing systems one task often freezes the whole interface until it is done such as PowerP
5. Towards Good Web Conferencing System Design for Ubi Media Collaboration Bin Yu Yong Rui Microsoft Research One Microsoft Way Redmond WA 98052 U S A t binyu yongrui microsoft com ABSTRACT Media data and documents are becoming ubiquitous in the past decade across time zones and across organization boundaries Web conferencing systems emerged as effective tools for people to communicate and collaborate These systems combine multiple distributed applications to manipulate multimedia content within a conferencing session and achieved great results However despite great development in such systems current products on the market are still far from perfect in many aspects In this paper we first present an overview of existing systems and then identify good system design principles based on our own experience with the existing systems Finally we outline several interesting research directions that may further enhance users collaboration experience 1 Introduction Web conferencing systems WCSs are the latest and one of the most promising developments in the collaboration world Its primary applications include project team collaboration training marketing presentation and customer support services We define a WCS as a combination of hardware and software utilities that enable information exchange between conferencing participants via computer networks in real time The hardware utilities include computing devices
6. all cost and increases reliability 3 4 Security Needless to say security is very important for WCSs and almost all the existing systems have made great efforts in securing the integrity and confidentiality of conferencing content Two most commonly used protections are password authentication and 128 bit Secure Socket Layer SSL encryption Because of page limitation for a detailed discussion readers are referred to 3 4 Future Directions Although quite many WCSs are on the market today users experience with them is still far from ideal In this section we propose a few interesting directions that may bring user experience to a higher level 4 1 Asynchronous Ad hoc Collaboration Existing WCSs all focus on real time collaboration However considering the popularity of the two widely used applications of the Internet www browsing and email asynchronous collaboration is a very important part of the collaboration experience For example sometimes it may be very hard to find a common time slot for a group of people to have a meeting together and in many occasions people need to meditate and search for related materials before they raise their opinions in a group discussion Consider a web forum way of asynchronous collaboration one participant may start a discussion thread by sharing a piece of video and PowerPoint slides on the conferencing catalog and then he gets offline Later when any other participant becomes online
7. andards such as H 264 and MPEG4 become widely used video will become more accessible in the future 4 5 Beyond What We Have Today A web conferencing session is more than a composite of several distributed applications for the following two reasons a there can be multiple users giving inputs to the same application and b these applications run at the same time and share common session metadata and critical resources such as CPU power and screen space There could be many new application scenarios that were not thought about before because of a For example before the wide use of WCSs it is rare that multiple users will work on the same document at the same time However now that every session participant has a set of mouse and keyboard they can work on the same whiteboard PowerPoint slide word document or spreadsheet at the same time Imagine that if a chip design company has an urgent project that normally takes each designer three days to finish now they can have these three designers work together on the same blueprint at the same time in parallel and finish the work in one day On the other hand because of b applications that work perfectly alone may need additional functions when used closely with other applications For example currently PowerPoint presentations take full screen mode only but when used in a web conferencing session it may be desired that it can run in a particular window such that it allows over
8. d network connection bandwidth Even if two users have similar availabilities of resources they may still want to allocate different amount of resource to a particular conferencing session Therefore it is desirable that a WCS gives advanced users the choice of specifying how much resource the system can consume For example in terms of screen space for the user interface it may not be a good idea to include all the functions into one large window that takes the entire desktop not to mention in an input blocking mode because the user may well want to take care of other applications at the same time NetMeeting 11 has done a good job in this aspect by using a small window for each task and left users the control of allocating the screen space Along this line of reasoning all types of Quality of Service QoS should be customizable based on resource availability and user requirements such as video quality audio quality PowerPoint presentation quality and session recording quality From our observation very few WCSs provide option for users to specify what the resource budget is and what level of quality is desired With the dynamic transcoding transformation techniques such adaptations are realistic to implement 3 2 2 Implementation Polymorphism Polymorphism refers to function overloading in object oriented programming languages i e for the same method call different objects act differently based on their own purpose of exist
9. e activities etc are stored separately Later on when a user wants to playback the session he can use the recorded events as natural indexes into the session and jump to any event to start the playback The system can quickly reconstruct the session state at the starting point as what it was during the original session then all the following interactions are replayed to simulate what happened in the original session There are several benefits of event based recording playback 1 a natural timeline with event based indexes is created as the conference session evolves 2 Playback quality is higher because the users see exactly what the original session would be while for video based recording there are normally quality loss due to down sampling and compression 3 If the user wants to download the recording for playback he will only download the documents and interactions so the file size can be greatly reduced compared to downloading a video based recording 4 For on demand browsing of meetings it requires much less bandwidth than streaming the actual video With the event based recording playback several other improvements can be achieved Conference Session Retrieval When the amount of recordings becomes large users may desire to search through recordings of conferences for specific information With traditional video audio recording because the video audio content is not easily understood by computers retrieval resu
10. ence We can borrow this idea into the design of WCSs because different users may have different computing devices or resource availabilities and we want the same function to be carried out in different ways based on each individual situation For example for the PowerPoint presentation facility currently almost all existing WCSs convert the PowerPoint file into an image format e g PNG or JPEG and then present the same presentation to all viewers This one size fits all approach may not be adequate some users may have high bandwidth connection and PowerPoint installed on their machine so that they can watch a PowerPoint presentation that runs on their own local machines and is controlled by the remote presenter on the other hand some users may only have a small iPAQ with limited wireless connection and the JPEG images would not fit into the screen Here if we apply the idea of polymorphism we can allow the same PowerPoint presentation function to be realized in a customized way for each participant For those clients with PowerPoint application installed whether it is on Windows Linux or Macintosh platform download the PowerPoint file and then run PowerPoint locally The presenter s interactions mouse movement or keyboard events can be sent to the participant s local PC to follow what would happen at the presenter s PC For those users without PowerPoint application installed they are sent differently sized
11. enerally provide more sophisticated This project was done during the first author s internship at Microsoft Research His current email is binyu uiuc edu To provide an unbiased view of existing WCSs because of authors affiliation we deliberately do not discuss Microsoft Live Meeting in this paper Title Bar Menu Bar Toolbar Audio Area Mt Video Panel Presenters Area Participants List tp Agenda Area Media Winddw Figure 1 An example WCS web interface from Centra 2 facilities e g better audio visual quality and more software utilities This is at the expense of higher price and higher resource requirement in terms of network bandwidth computation power and capturing devices On the other hand some WCSs weight simplicity with more importance and they focus on a few key features that work well enough for most daily activities Representative simple WCSs include Glance 8 Convoq ASAP 5 Sightspeed 17 and Linktivity Webdemo 10 They focus on smaller scale conferencing scenarios for individual users and small companies and often ask for much lower prices For example Glance 8 simplifies several collaboration features into the application sharing facility which may not be best for large group of participants but fits well to the needs of smaller group of users Despite the differences in comprehensive and simple systems there are many common issues that both camps need to
12. lay of a small Picture in Picture window that shows a video window or another PowerPoint slide or even a web page 5 Conclusion WCS is a key solution to improving people s ubiquitous access to media data and information As a result it can significantly improve people s efficiency and productivity in their daily business especially when they are distributed Based on our own research experience as well as the observations on commercially available WCSs we reviewed the strength and weakness of existing WCSs proposed a set of design guidelines and discussed interesting future research directions As the world is becoming more flat we envision that future WCSs will play more and more important roles in helping people access manage and collaborate on their data 6 Reference 1 Best Web And Videoconferencing Alternatives To WebEx Live Meeting Centra For The Small Non Profit And Home Based Company http www masternewmedia org 2003 1 1 13 best_web and_videoconferencing_alternatives htm 2 Centra http www centra com 3 Cisco Best practices in web conferencing security http itpapers techrepublic com abstract aspx docid 8 3438 amp promo 40011 1 amp lop wpr 20 1011 white paper 4 Conferguide 2004 web conferencing guide http www conferzone com services conferguide_thoit html 5 Convog ASAP http Awww convog com 6 Cybernar from Terra Firma http www terrafirmacomm com product
13. lts are often dissatisfactory However with the event based recording two advantages exist 1 It preserves the related documents in their original formats which are normally textual so we can leverage the more mature techniques in text based retrieval 2 Metadata e g events is logged which can be used for retrieval Conference Session Summarization Summarization of a long conference session into a short highlight segment is often desirable for faster browsing and searching for specific information With traditional video audio recording summarization is not easy because of the limitation in video audio content understanding technologies However with event based recording we have the natural indexes that segment the session into small shots so summarization can be done by prioritizing these shots so that more interesting and important shots are presented to users who want a quick review of the session Specifically the priorities can come from two sources content analysis and user interaction analysis For content analysis approach the shots in a session can be weighted differently based on whether important events happened during that shot and whether the related document segments contain important interesting information Note that heuristics may be needed to determine the importance of events and what information is more important or interesting and this knowledge may come from the particular conference topic o
14. oint file uploading or application sharing That is when a user is using these features he cannot access any other features from the interface This is very likely to cause the whole interface to crash if an error occurs during the file uploading We believe that a more robust design is to model all the facilities as independent applications sharing a minimal set of session information 3 3 2 Distributed Architecture A centralized server is usually the source of problem because it has high traffic computation pressure and it is often the target of attack To increase scalability and robustness a good WCS should be designed with distribution of functionality in mind As personal computers become more and more powerful more tasks could be off loaded to the client end from the shared server For example currently most systems store the meeting content in a centralized server and then distribute to all participants on request This is not reliable because if the content server is down the meeting can not continue Instead considering the low price of hard disks it is better to replicate the content to a selected set of powerful participant PCs before hand In fact some systems e g Groove 9 and Cybernar 6 are completely server less and they adopt the Peer to Peer architecture to remove the single point failure and utilize the computing power residing on each participating PCs This is a very promising direction to go that reduces over
15. properly address In the rest of the paper we want to identify such design principles that are worth to follow for all WCSs and promising future directions that may eventually lead to a solution that best serves the customers 3 Detailed System Design Principles 3 1 Ease of Use Ease of use has always been the top design principle for all computer systems and web conferencing is no different After using and studying many existing systems we summarize the following key principles that can lead to ease of use 3 1 1 Following Users Previous Experience The easiest way to teach a user how to use a new tool is to make it work like an old tool that the user is already familiar with By previous experience we mean both the experience in using other computer tools and the experience that are not related to computers at all For example the Glance 8 system achieves great simplicity by unifying almost all conferencing tasks into one facility desktop sharing For example distant PowerPoint presentation is extremely easy because the presenter does nothing more than running a local PowerPoint presentation Similarly Convog ASAP 5 is very easy to use for all users who are already familiar with IM tools such as Yahoo Messenger 20 because all conferencing facilities are naturally built on top of existing IM interface This principle of experience driven design can be used to simplify many tasks For example the file sha
16. r be manually specified by users For user interaction analysis approach the log analysis approach 21 can be applied to utilize users engagement and interactions to gain understanding of the session semantics Specifically there are natural inherent links between media content such as PowerPoint slides web slides whiteboards and shared applications and interesting pieces of content will tend to be strongly correlated to each other On the other hand playback users differ in their interests in the materials and engagement in the browsing process so their interaction will have different weights in determining the value of the content segments they visit Therefore by utilizing the reinforcement between engaged users and interesting content pieces we can rank the recorded content pieces in their interestingness to users and assist future users in their browsing Adaptable Recording Currently almost all WCSs publish final recording files that can not be updated later With event based recording the whole session is segmented into small shots based on different events which provides the opportunity for later users to re join a past conference session by inserting his own interactions For example for a distant learning class the teacher may ask each student to present his her ideas on a topic Imagine that one student is absent from that class he can make up the class by browsing through the recording
17. rily facilitate people to exchange quick textual messages while WCSs provide much more powerful visual audio channels for collaborative discussion on more complicated problems However one interesting trend in the WCSs development is to invoke collaboration tools such as PowerPoint presentation audio video conferencing and whiteboard from within the IM interface There exist several comprehensive surveys and guides on web conferencing products and services from end users perspective e g 3 14 15 There is however little research on WCS design issues This paper tries to fill that gap Specifically we want to 1 identify WCS design principles that should be encouraged or avoided based on the authors first hand experiences and 2 suggest future research directions that may lead to significant improvement in user experience with WCSs The rest of this paper is organized as follows We will first give an overview of existing WCSs in Section 2 and then present system design principles in Section 3 We promote several future research directions in Section 4 and conclude the paper in Section 5 2 Overview of Existing WCSs There are many WCSs on the market today In general there are two major competing trends in the WCS industry On one hand some systems target at large organizations to reduce their huge travel costs by providing comprehensive solutions Example systems include WebEx 19 and Centra 2 Such systems g
18. ring feature is not straightforward in most WCSs because a user often has to explicitly send receive upload or download the files However considering that users are familiar with simple copy and paste or drag and drop operations we can create a pseudo drive directory on the local PC s file system that represents remote peers so that users can resort to what they already know 3 1 2 Hide What Is Not Being Used Many a time the complexity of using a WCS comes when a user cannot easily find the controls that s he needs because there are too many menus and buttons For example as the authors tried out some WCSs that provide rich functionalities we found it s not easy to find the menu item or button on the toolbar when we wanted to quickly change or check some settings or repeat the same action To solve this issue it is better to define several working modes e g application sharing mode Internet co browsing mode presentation mode so that in each mode the toolbar and menu items are adapted to the hot tasks for that mode 3 2 Customization Customization gives a user the control over what kind of service he she enjoys and we believe a good WCS should provide customizability in the following aspects 3 2 1 Resource Consumption Level Different users have different resource availabilities in terms of hardware capacity CPU memory disk screen space etc an
19. s cybernar ph 7 Frost and Sullivan http www frost com 8 Glance http www glance net 9 Groove http www groove net 10 Linktivity webdemo http www linktivity com 11 NetMeeting http www microsoft com windows netmeeting 12 Orbitalk http Awww orbitalk com 13 PolyCom http www polycom com 14 Rich Media Conferencing 2004 http www wainhouse com reports rmc2004 html 15 Robin Good s official guide to web conferencing and live presentation tools hypeen tedi ot SUR Ed n g guide 16 Rui Y Huang T S and Mehrotra S Constructing table of content for videos Multimedia Systems V 7 Issue 5 September 1999 17 Sightspeed http www sightspeed com 18 Wainhouse Research Bulletin Archives Vol 4 Issue 44 http www wainhouse com files wrb 04 WRB 0444 pdf Dec 8 2003 19 WebEx http www webex com 20 Yahoo Messenger http messenger yahoo com 21 Yu B Nahrstedt K Video Summarization based on User Log Enhanced Link Analysis ACM Multimedia 2003
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