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<HTML><HEAD><TITLE>Chapter 26 -- How Intranet Whiteboard Applications Work</TITLE><META></HEAD><BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#0000EE" VLINK="#551A8B" ALINK="#CE2910"><H1><FONT SIZE=6 COLOR=#FF0000>Chapter 26</FONT></H1><H1><FONT SIZE=6 COLOR=#FF0000>How Intranet Whiteboard ApplicationsWork</FONT></H1><HR><P><CENTER><B><FONT SIZE=5><A NAME="CONTENTS">CONTENTS</A></FONT></B></CENTER><UL><LI><A HREF="#HowIntranetWhiteboardApplicationsWork">How Intranet Whiteboard Applications Work</A></UL><HR><P>Increasingly, people's work is done not with pen and paper-it'sdone with computers. That means that one traditional way thatpeople collaborate-by sitting down with pen and pencil and markingup each other's work-is no longer possible. <P>Online mark-up started with word processing programs offeringsimple "strikeout" and "redline" styles. Changes,however, were done sequentially, one person at a time. This oftencaused great delays in document production. It was also difficultto make annotations in documents, although "comment"styles were possible. Another difficulty was keeping track ofwho made which changes or remarks. This was improved upon by theintroduction of color coding revisions by authors. Despite theseadvances, it was still cumbersome and time consuming for a groupto work online on documents. Furthermore, while these featuresrapidly become common in word processing, other applications likespreadsheets didn't offer similar controls. One other problemwas that all the people working on the document usually neededto have the same version of the software to work collaborativelyat all.<P>True document collaborative possibilities emerged when someonerecognized that whiteboards-a board on which special markers areused that can easily be wiped off-provided the concept that couldhelp move online mark-up into the realm of the actually useful.These whiteboards are not physical objects set up in rooms. Instead,the whiteboard software resides on the client's desktop. Everycomputer screen has the ability to become a whiteboard. In additionto writing on a blank whiteboard, people can "write"directly to the documents by writing on their computer screens.<P>What they write is immediately visible to the other people viewingthe document on their screens. People can mark up the budget bycircling or otherwise marking items, each using a different colorto help identify the author. Different programs also provide avariety of tools, such as erasers and spray cans. Participantscan also discuss the comments as they make them.<P>The next generation of whiteboard applications will allow participantsnot only to mark up what is on each other's screens, but alsoto actually change the data as well. Presently, only the originatorof the document conference can physically change the data. Inthe future, however, no doubt there will be controls that allowor restrict the changes that people participating in a whiteboardsession can make. Participants will be able to talk about a budget,change the figures on the spot, and perform a "what-if"analysis. Moreover, participants will be able to do this evenif they do not have the software for the file on the whiteboard.For example, if they were working on an Excel spreadsheet, theywould not have to have Excel on their own computer.<H2><A NAME="HowIntranetWhiteboardApplicationsWork"><FONT SIZE=5 COLOR=#FF0000>How Intranet Whiteboard Applications Work</FONT></A></H2><P>A <I>whiteboard</I> <I>application</I> refers to software whichallows people to simultaneously view and annotate a document ontheir computer screens. Each participant would have a differentcolor assigned so that the authorship of changes is easily visible.The participants in a whiteboard conference can also talk to eachother while they are circling or otherwise pointing to the sectionof the document they reference in the discussion. Document conferencingby whiteboard applications allows for truly collaborative working.There are a number of companies developing this type of software.This illustration is based on how the CU-See-Me whiteboard works.<OL><LI>The CU-See-Me whiteboard works in concert with its videoconferencingsoftware. (See <A HREF="ch25.htm" >Chapter 25</A> for more information about how videoconferencingworks.) The software works on a client/server model. People runthe CU-See-Me client on their computer and they log into a specialserver called a <I>reflector</I>. When you log into a reflector,you can join any whiteboard conference found there. When someoneis logged into a reflector, a signal goes out regularly from theperson's computer to the reflector, telling everyone connectedto the reflector that the person is logged in and available fora conference.<LI>In a whiteboard conference, you can see what is on other people'scomputer screens, and they can see what is on your screen. Youcan also mark up what is on your screen or their screens by usingyour mouse or stylus as a drawing tool. In the same way, theycan mark up what is on your screen.<B> </B>People participatingin a whiteboard conference can see multiple screens on their computerat once-so that they can be participating in marking up severalscreens at the same time. People can decide to only view the markingsof certain people in a whiteboard session-they can "turnoff" the markings of some people.<LI>When you participate in a whiteboard conference, a specialprotocol is used for sending data packets. The protocol allowsdata to be sent to many people at once, instead of having to specifysending it to an individual-that is, to <I>multicast</I>. Thepacket is sent to the reflector, which multicasts it. However,the protocol also works similarly to TCP: It checks to see whetherevery packet in the data has been sent. If every packet hasn'tbeen sent, the protocol re-sends the packet until every packetis received.<LI>The protocol has been designed so that it can keep resendingdata to those people who haven't received all the packets, butnot resend to those who have received the packets. For example,if four people are participating in a whiteboard conference, andonly one person hasn't received all the packets, the reflectorwill re-send the packets only to the individual who hasn't receivedall the packets.<LI>The multicast protocol used by CU-See-Me allows for the whiteboardsession to be broadcast to a large number of people simultaneously,and any one of those people can choose to participate in the whiteboardconference. It is also possible to participate in whiteboard sessionswithout having to go through a reflector. However, when reflectorsaren't used, intranet administrators are not allowed to do thingssuch as control the bandwidth used for whiteboard sessions. See<A HREF="ch25.htm" >Chapter 25</A> on videoconferencing for information about how intranetadministrators can use reflectors to regulate sessions.<LI>In the future, whiteboard applications will allow people notmerely to mark up documents, but to work together on the document,even if they don't have the application that created it on theirown computer. People would be able to put in new figures in aspreadsheet, for example, and engage in group "what-if"scenarios, without everyone having to have the application thatcreated the data on their own computers.</OL><HR><CENTER><P><A HREF="ch25.htm"><IMG SRC="PC.GIF" BORDER=0 HEIGHT=88 WIDTH=140></A><A HREF="#CONTENTS"><IMG SRC="CC.GIF" BORDER=0 HEIGHT=88 WIDTH=140></A><A HREF="contents.htm"><IMG SRC="HB.GIF" BORDER=0 HEIGHT=88 WIDTH=140></A><A HREF="ch27.htm"><IMG SRC="NC.GIF" BORDER=0 HEIGHT=88 WIDTH=140></A><HR WIDTH="100%"></P></CENTER></BODY></HTML>⌨️ 快捷键说明
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