In this paper we present a software toolkit for deploying peer-to-peer distributed graphical user interfaces across four dimen-sions: multiple displays, multiple platforms, multiple operating systems, and multiple users, either independently or concurrently. This toolkit is based on the concept of multi-purpose proxy connected to one or many rendering engines in order to render a graphical user interface in part or whole for any user, any operating system (Linux, Mac OS X and Windows XP or higher), any computing platform (ranging from a pocket PC to a wall screen), and/or any display (ranging from private to public displays). This toolkit is a genuine peer-to-peer solution in that no computing platform is used for a server or for a client: any user interface can be distributed across users, systems, and platforms independently of their location, system constraints, and platform constraints. After defining the toolkit concepts, its implementation is described, motivated, and exemplified on two non-form based user interfaces: a distrib-uted office automation and a distributed interactive game.

1. Jérémie Melchior, Donatien Grolaux, Jean Vanderdonckt, Peter Van Roy
Jeremie.Melchior@uclouvain.be
Researcher at BCHI, http://www.isys.ucl.ac.be/bchi
Université catholique de Louvain (BELGIUM)
EICS 2009 - July 15

2. Outline - Motivations
• Multi-user user interfaces
• Multi-device environments
• Multi-platform user interfaces
• Toolkit for distributed user interfaces
• Peer-to-Peer distribution
• Demonstration
• Future work

3. Motivations

4. Multi-user user interfaces
User Group
System
User 1 User 2 User NU
• Whenever
• Wherever

5. Multi-device environments
User 1 User 2 User NU
User Group
Device 1 Device 2 Device ND

6. Multi-platform user interfaces
User 1 User 2 User NU
User Group
Device 1 Device 2 Device ND
CP 1 CP 2 CP N
CP 1 CP 2 CP N
CP 1 CP 2 CP N

7. Toolkit for distributed user
interfaces
• Three-layer structure :
o Application - user interfaces
o Ext/Tk - toolkit for migration and adaptation
o Mozart - for the distribution layer
Application
Ext/Tk
Mozart

8. Toolkit for distributed user
interfaces
• Application layer :
o UI is dynamically migratable
•
o UI is dynamically adaptable

9. Toolkit for distributed user
interfaces
• Ext/tk : 1°) Creation of the UI
UI={Build window( name:window
selector( name:selector
items:["Radiobuttons" "Listbox" "Menu"]
curselection:1
text:"Selector"
action:
proc{$}
R={UI.selector get(curselection:$)}
in
{UI.selector setContext((default#listbox#menu).R)}
end
))}
{UI.window show}

10. Toolkit for distributed user
interfaces
• Ext/tk : 2°) Migration of the UI
{Offer {UI.selector
getRef($)}}
UI2={Build
window(name:window)}
{UI2.window show}
{UI2.window
display({Obtain})}

11. Toolkit for distributed user
interfaces
• Mozart : Multi-paradigm programming language
o Strongly dynamically typed
o Procedural, Object-Orientation
o Functional, Logic and Symbolic programming
o Transparent distribution support
 Distributed network protocols are attached automatically to
some of the native data types of OZ

12. Proxy W Renderer W
Site A
Peer-to-Peer distribution
• Widget : Proxy + Renderer
Proxy W
Site A
Renderer W
Site B
• Proxy = stationary, functional core
• Renderer = distributed, user interaction

13. Demonstration
• Mozart :

14. Demonstration
• Ext/tk

15. Future work
• Android support
• Transparent migration of the top level widget
• Compatibility with Mozart 1.4.0 and newer
• High-level operations (window migration, widget
copy, ...)

16. Bibliography
• Donatien Grolaux, Transparent Migration and
Adaptation in a Graphical User Interface Toolkit,
Ph.D. dissertation, Department of Computing
Science and Engineering, Université catholique de
Louvain, Sep. 2007.