1. Building Distributed Educational Applications using P2P
Tomasz Müldner* and Gregory Leighton
Jodrey School of Computer Science, Acadia University, Wolfville, NS, Canada
* presenting
Edmedia, June 23, 2004

2. Contents Distributed computing Peer-to-Peer (P2P) JXTA P2P framework
APEX
Edmedia, June 23, 2004

3. Distributed Applications
A distributed system:
data and functionality are distributed
across multiple
machines
connected by a
network
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4. Examples of Distributed Educational Applications
groupware or computer-supported cooperative work (CSCW)
electronic classrooms
shared workspaces
others
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5. Distributed Applications: Limitations
Problems:
firewalls
dynamic IP addresses
network address translation (NAT)
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6. Goals and Requirements for Distributed Educational Systems
Platform Independence: users of heterogeneous systems must be able to access the application:
Corba
Web Services and the underlying XML technology
Java technology
Security: an authentication and a permission system with access control rules:
authentication e.g. using digital signatures
encryption e.g. using private or public key systems
auditing
Edmedia, June 23, 2004

7. Goals and Requirements (2)
Customizability:
an application can be customized
Extensibility:
new tools can be added without affecting the operation of existing tools.
Edmedia, June 23, 2004

8. Goals and Requirements (3)
Connectivity:
work on course documents while disconnected;
synchronized upon the next reconnection
Identification:
Availability of the identities of users who are currently available (independent of her current location)
Edmedia, June 23, 2004

9. Goals and Requirements (4)
Categorization:
two kinds of user’s roles:
- a single user
- a group
Collaboration:
threaded discussions, messaging,
collaborative viewing and editing of shared documents
Edmedia, June 23, 2004

10. Goals and Requirements (5)
Discovery:
users can discover and join course groups:
course group contains a set of services specified by the instructor
services are dynamically discovered when a user joins a course group
Scalability:
the addition of new entities or services to the network does not significantly hinder application performance
Edmedia, June 23, 2004

11. Goals and Requirements (6)
Reliability:
the availability of the application must not
depend on the availability of any single
application instance;
Accessibility:
application entities must be able to
communicate with one another
Edmedia, June 23, 2004

12. P2P Each peer typically acts in both the client and server roles
A peer may initiate requests on services hosted by other peers
A peer can service incoming requests on locally-hosted services
Edmedia, June 23, 2004

13. Introduction to JXTA
A set of protocols to establish an overlay network on top of existing network protocols such as TCP/IP and HTTP.
The overlay network transparently connects systems in a reliable and persistent manner
The atomic entity in the JXTA network is the peer:
a software program that uses the JXTA protocols to interact with other peers.
Edmedia, June 23, 2004

14. APEX
An extendable architecture: various components can be added to provide the required functionality; e.g.:
an instant messaging component
other components may be added as required, (e.g. components that support cooperation and collaboration)
Edmedia, June 23, 2004

15. Authentication
APEX performs authentication of each peer as it joins the network via a lookup on the institution’s registration records
Each course section is modelled as a separate JXTA peer group
Edmedia, June 23, 2004

16. User Roles Student peers Teaching assistants Instructors
Administrators
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17. Architecture and Functionality
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18. Example of an Instant Messaging Component IM
Each member of the course peer group runs an instance of IM:
maintaining a collection of ongoing conversation sessions involving the local user,
associating incoming chat messages with the appropriate conversation session
forwarding outgoing chat messages to the appropriate conversation partner
displaying an ongoing history of each ongoing conversation session to the end user.
Edmedia, June 23, 2004

19. Conclusions
We have designed and partially implemented APEX, an educational application, based on JXTA.
All implementation requirements have been satisfied.
APEX forms a base
Edmedia, June 23, 2004

20. Future Extensions Future extensions to APEX :
electronic submission and grading of course assignments
The addition of a component for audio/video conferencing
A dynamic course syllabus could be provided to specify assignment due dates and scheduling of midterms and final exams.
Edmedia, June 23, 2004