Building%20Distributed%20Educational%20Applications%20using%20P2P

1
Building Distributed Educational Applications
using P2P

• Tomasz Müldner and Gregory Leighton
• Jodrey School of Computer Science, Acadia
  University, Wolfville, NS, Canada
• presenting

2
Contents

• Distributed computing
• Peer-to-Peer (P2P)
• JXTA P2P framework
• APEX

3
Distributed Applications

• A distributed system
• data and functionality are distributed
• across multiple
• machines
• connected by a
• network

4
Examples of Distributed Educational Applications

• groupware or computer-supported cooperative work
  (CSCW)
• electronic classrooms
• shared workspaces
• others

5
Distributed Applications Limitations

• Problems
• firewalls
• dynamic IP addresses
• network address translation (NAT)

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

7
Goals and Requirements (2)

• Customizability
• an application can be customized
• Extensibility
• new tools can be added without affecting the
  operation of existing tools.

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)

9
Goals and Requirements (4)

• Categorization
• two kinds of users roles
• - a single user
• - a group
• Collaboration
• threaded discussions, messaging,
• collaborative viewing and editing of shared
  documents

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

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

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

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.

14
APEX

• An extendable architecturevarious 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)

15
Authentication

• APEX performs authentication of each peer as it
  joins the network via a lookup on the
  institutions registration records
• Each course section is modelled as a separate
  JXTA peer group

16
User Roles

• Student peers
• Teaching assistants
• Instructors
• Administrators

17
Architecture and Functionality
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.

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

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.