4th International Conference on Principles and Practices ... - MADOC

Peersí normal login and logout messages are sent using the
method of Type-A sendMsg( ). In the same way a community
ping-pong message is sent using community message mode. A
peer who logins to or logouts from the JXTA network sends a
message to all other peers to inform its existence or absence. In
addition, the peer sends a ping message to all other peers in the
same room and community every 2 minutes. If a peer does not
reply for several requests, it will be automatically excluded from
the community/room.
A peer in a room can be assigned some roles such as a group
leader or member for synchronous collaborative work. Peersí
roles are managed by the identity control as follows.
• Chair to control the identities of other peers and also play a
coordinative role in a room.
• Player to be able to control shared space and manipulate
shared applications, such as a game player or meeting
presenter in the real world.
• Observer to only watch the shared space and applications
but have no right to manipulate the space and applications.
3.3 PeerCommunication Support
The PCS provides built-in communication tools to collaborative
processes for administrating rooms and using shared applications.
The SMT offers three transmission service modes: community,
room and one-to-one to send a message to all peers, room peers,
and an individual peer, respectively. Each mode uses its own pipe
corresponding to a related pipe advertisement.
3.4 ApplicationSpace Management
ASM consists of a space manager to control the shared space, and
an application manager to control operations on shared
applications. Both managers are related to peersí identities (chair,
player and observer) in a room as shown in Fig. 7. A presenter
peer in a room has initiative to operate a virtual space or shared
applications, but others can only see what he/she has done. A
chair is able to change other peersí identities.
4. M3PS APPLICATION TOOLS
In this section, we present four application tools of M3PS: INFO,
JDP, SWB and SA.
4.1 INFO
The INFO application tool gives the information of the peers in
M3PS community. So, if a peer is logged in the system, the other
peers can get the information and communicate together. In the
top of main window of INFO tool are shown also other tools such
as JDP, SWB and SA. Therefore, if a peer wants to shift to other
applications, he can use this panel to change his mode to other
tools. In the center of INFO window are shown: Room Name,
Room Description, Room ID, Chair Peer and Presentation Peer.
On the top in left side frame are shown: Peer Name, Room Name,
Collaboration Mode and Peer Identity. In the middle frame (left
side) is shown <strong>Conference</strong> Room and in the bottom frame
Community information. The display captures of INFO for Linux,
and UNIX are shown in Fig.8 and Fig. 9, respectively.
Identity Control
Chair Peer
Observer Peer
Presenter Peer
Shared
Applications
TOMSCOP
Space
Shared
Applications
TOMSCOP
Space
Shared
Applications
TOMSCOP
Space
E
E
E
E
E
E
Application
Manager
Space
Manager
Application
Manager
Space
Manager
Application
Manager
Space
Manager
D
D
D
D
D
D
SMT
SMT
SMT
Figure 7. ApplicationSpace management.
Figure 8. INFO in Linux.
Figure 9. INFO in UNIX.
M
M: Message
E: Event
D: Data
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