Desarrollo de una arquitectura software para aplicaciones de educaci

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IEEE Sixth International Symposium on Multimedia
Software Engineering
MSE 2004 December 13-15, 2004, Miami, FL (U.S.A.)
A Technological Framework for TV-supported
Collaborative Learning
Alberto Gil Solla Department of Telematic
Engineering University of Vigo (Spain)
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Organization

• Introduction to t-learning.
• The MHP standard.
• An architecture for virtual communities.
• Implementation details.
• Summary and future work.

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A Few Words about t-Learning
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Introduction
A lot of work is being done on distance
learning. In order to overcome the limitations of
traditional learning. Difficulties in the use of
computers. Limited penetration of
computers. Uneven presence of broadband
infrastructure. Access to education is considered
key to maintain a regions competitiveness.
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Introduction
Several major technological approaches have been
defined.
The future points towards convergence. Obstacles
networks, interoperability and users. Currently,
the different mediums demand different solutions.
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T-Learnings Advantages...

• There is at least one TV in nearly 100 of
  households in developed countries.
• Internet not expected to go beyond 70
• Television is easy to use for everybody.
• IDTV helps to prevent social exclusion in the
  access to education.
• Overcomes economical and cultural barriers.
• No need to buy a computer.
• No need of technological knowledge.

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... and Peculiarities

• A set-top box is not a computer.
• Lower computing power.
• Limited user interaction capabilities.
• A TV screen has low resolution.
• Simple user interfaces with big visual elements.
• IDTV is a natural medium for broadcast and
  handling multimedia content.
• Users are predominantly passive.
• TV is considered as a medium for entertainment.
• IDTV is ideal for informal learning (edutainment).

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Strategies for Interactivity
User-driven
Applications respond to the users
actions. Typical in e-learning services.
Media-driven
The evolution of pieces of media guides users and
controls the flow of applications. Main option
for t-learning.
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but the Situation is Changing

• The new IDTV promotes a users active role.
• The increasing availability of high-quality
  bi-directional networks.
• From simulated interactivity (with contents) to
  real interactivity (with service provider and
  other users)
• Creation of virtual learning communities.
• Mitigates feeling of isolation.

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The MHP Standard
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The Multimedia Home Platform

• Published by the DVB (Digital Video Broadcasting)
  Consortium in February, 2000.
• It defines a neutral framework for IDTV
  applications and services.
• Communication in IDTV is highly asymmetric.
• Broadcast networks and (optional) return
  channels.
• The availability of a return channel determines
  the interactive capabilities (simulated vs. real
  interactivity)

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MHP Architecture
MHP API
Interaction Channel
MPEG Processing
Graphics
Resources
CPU
Memory
I/O Devices
Broadcast Channel
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Types of Applications
DVB-J

• Applications programmed in Java.
• Two main restrictions
• MHP APIs.
• Xlet lifecycle.

DVB-HTML

• A declarative language, based on Internet
  standards.
• XHTML, CSS, cookies, etc.

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MHP Broadcast Channel

• MPEG-2 transport streams for broadcasting live
  audio and video, and DSM-CC object carousels for
  other resources.

Applications
MHP APIs
DVB-SI
UDP
DVB Object Carousels
UDP
Información de servicio
Carrusel de objetos
IP
DSMCC Object Carousels
IP
Carrusel de datos
DSMCC Data Carousels
Multiprotocol Encapsulation
Encapsulación multiprotocolo
MPEG-2 Sections
MPEG-2 transport stream
Broadcast channel
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The Object Carousel

• Main mechanism to broadcast data in MHP.
• A group of files transmitted in a cyclical way.
• A read-only filesystem over an MPEG-2 transport
  stream.
• Resources are not always available immediately
  when needed.
• There may be noticeable latencies.

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MHP Return Channel

• TCP/IP and service-specific protocols for the
  return channel.

Aplicaciones
Applications
API
MHP APIs
UDP
Información de servicio
Carrusel de objetos
Service specific protocols
UDP
HTTP/ HTTPS
DSM-CC User-to-User
IP
UNO-RPC/ UNO-CDR
Carrusel de datos
Encapsulación multiprotocolo
TCP
Secciones MPEG-2
IP
Flujo de transporte MPEG-2
Network dependant protocols
Canal de difusión
Return channel
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Principles of the Architecture
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Structure of the Courses
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New Spatial Distribution
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Contextual Binding

• A simple and effective solution for the
  synchronization of multiple sources of
  information.
• Including the broadcast streams (media-driven
  units).
• Based on contexts.
• Identifiers linked to pieces of information.
• Defined differently for the different types of
  content.
• Timestamps in fragments of audio and video.
• Regions in images.
• Anchors in a text.
• Options in menus, etc.

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Templates (I)

• A common feature in many development tools make
  development tasks faster, enhance software reuse,
  help to separate content from graphical
  appearance.
• Configured during runtime, not at design time.

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Templates (II)

• The object carousel transports
• The Java class file of the template.
• Auxiliary files to compose the scene.
• Much smaller XML configuration files.
• The cost of runtime configuration is masked by
  latencies and loading times.
• Advantages
• More files can be kept in the cache ? Higher
  efficiency
• The size of the carousel decreases.
• Lower round-trip time?? lower latencies.

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ImplementationDetails
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Design Goals

• No need of programming knowledge.
• Flexibility and support for all the phases of
  development.
• Based on free, open technologies.
• Low cost.
• Extensibility.
• Interoperability.
• Active agents produced DVB-J applications

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Foundational Technologies XML

• A standard syntax for
• the composition of the courses,
• the configuration files for a template,
• the structure of communication messages,
• the definition of contexts in the different types
  of information.
• Also used when assembling pedagogical units.
• To communicate with other content-management
  systems or information repositories.

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Foundational Technologies JavaBeans

• A components architecture for Java.
• Promotes components reuse.
• Provides for visual development.
• Beans are building blocks to construct
  applications.
• Interrelations handled by means of event
  adapters.
• Enough for simulated interactivity.
• Not for non-broadcast services.

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Foundational Technologies JXTA

• Open-source API to support peer-to-peer
  communications.
• Language and platform independent.
• Favours decentralisation, as needed in a
  collaborative t-learning context.
• Supports multicasting and addresses important
  issues such as resource discovery or group
  management.

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JXTA and Virtual Learning Communities

• JXTA provides support for direct interaction
  among users,
• enabling the establishment of virtual learning
  communities.
• Rendezvous super-peers to publish and locate
  information.

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JXTA Broadacst Relays

• JXTA super-peers to deal with heterogeneous
  networks.
• We use them to connect broadcast and IP networks.

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A CASE Tool for t-Learning

• Implemented on top of the NetBeans Platform.
• Entirely visual development.
• Simple assembling of pedagogical units.
• By retrieving content from repositories or
  creating it ad-hoc.
• By placing JavaBeans in the different scenarios.

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A CASE Tool for t-Learning

• Several wizards and assistant tools.
• To define the composition of the courses.
• To delimit contexts in the different types of
  information.
• To specify interaction patterns among peers.
• For the automatic creation of multiple-choice
  tests.
• Automatic generation of the applications.

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Time
Context
Text
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Summary and Future Work
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Conclusions

• Human and technical factors advice against direct
  translation of e-learning solutions.
• Essential distinction between user-driven and
  media-driven strategies.
• An architecture for highly-interactive
  t-learning, that promotes the establishment of
  virtual learning communities.
• MHP provides a quite satisfactory platform for
  t-learning, though it lacks many-to-many
  communication facilities
• Our approach contributes to openness of
  educational market, enabling new business models
  for broadcasters.

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Future Work

• Enhance the CASE tool develop more beans with
  extended functionality
• Test scalability in a real broadcast environment
• Integrate new multimedia formats MPEG-4.
• Personalization looking for interesting
  educational contents.