After requesting a Tango download of control applet, one may get a security dialog (grant permission to download and remember decision), and first one is asked (as on previous page) to choose a server
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Servers are available for distribution but typically start with default one
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one also asked to choose a "control interface" which just correspond to different selections of applications to share
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After a while, if all goes well, one gets the request to "login" which currently just requires that you type in a unique "handle" by which you are known in the collaboration room.
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In Tango1, each server supports a single room but we will see that although all users are potential participants in a shared application, one can set up complex relationships as any given session can involve a different subset of users.
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Currently Tango has no security mechanisms in the login process although one has some control over allowed actions in a given shared application.
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Note we define a session as an instance of an application shared by a set of users. One can have any number of sessions based on a given application which separate instantiations of the application and different subsets of users. As we will see users decide who joins a given session.
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Sessions can either be started or joined
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Sessions can be joined either because the master adds a user or because a user requests it.
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Sessions are started from the icons under the tags in the middle of the CA's user interface
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Suppose the teacher has started a chat or other session. Then it appears on the list of sessions at the bottom middle section for ALL clients. Highlighting it, one see that join is an option (shown in left bottom panel)
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Click the join button and you become part of this session
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The chat applet is downloaded to client that joined. Highlighting chat now shows this client as a participant.
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For chat, this happens almost instantaneously. For more complex applications, the registration process takes longer as Tango only accepts a joined client when The Java applet is properly loaded
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We showed how users could be added to sessions by clients joining a session initiated by the master.
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Alternatively, one can use a remote open command shown on previous and next two pages
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This is appropriate when one is sure that a group of users need to participate. This is typically the case in a distance education class when students have logged into Tango and teacher wishes to launch a shared application (e.g. the cross-product applet) on all student machines.
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When teacher highlights the cross-product session (and no other users have joined), he or she is offered the allowed choices:
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local close which will terminate session or
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remote open which can spread session to any of the other users
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The dialog box that jumps up allows one either to select specific users or all -- the latter is a good option for education when one typically wants all students involved.
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We will see later how the configuration tab, allows clients to prevent unwanted remote opens cluttering their windows
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Microsoft currently supplies NetMeeting for Windows 95/98/NT
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This supports a different model for sharing
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When you share Word for example, there is only one copy of application running on the master
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In Tango classic shared event model, the application (e.g. spring applet) runs separately on each machine
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At its simplest, NetMeeting shares the "display" (frame buffer produced by application)
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This explains curious hatched area on following page. This corresponds to part of Word window that is obscured on the master but not on the slave.
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NetMeeting captures mouse and keyboard actions in the shared window and treats these as shared events
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This allows shared editing with a difficult master-slave model
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This is an example of Tango interfacing to a C++ client application -- Microsoft's NetMeeting
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There are other capabilities of Control Application with users, mailbox, configuration and help tabs
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The users tab can tell you more about all the users who are logged into the Tango Server
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Their handle (login name), name of their client machine, status message, and time they last changed status
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Each user is responsible for setting status message
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On next page, we show the result of double clicking on a given user.
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Up pops more information!
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You can ping the user -- send a message to see the user machine is still alive.
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If the ping works, try a hail which tries the wake the user up so he or she can collaborate with you.
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Use a chat window to have a more detailed dialog with a hailed user
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