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)
Organization
• Introduction to t-learning.
• The MHP standard.
• An architecture for virtual communities.
• Implementation details.
• Summary and future work.
A Few Words about t-Learning
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 region’s
competitiveness.
Introduction
Several major technological approaches have been defined.
t-learning
e-learning
Continuous,
ubiquitous learning
m-learning
The future points towards convergence.
Obstacles: networks, interoperability and users.
Currently, the different mediums demand different solutions.
T-Learning’s 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.
... 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).
Strategies for Interactivity
User-driven
Applications respond to the
user’s 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.
but the Situation is Changing
• The new IDTV promotes a user’s active role.
• The increasing availability of high-quality
directional networks.
bi-
• From simulated interactivity (with contents) to real
interactivity (with service provider and other users)
• Creation of virtual learning communities.
• Mitigates feeling of isolation.
The MHP Standard
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)
MHP Architecture
Application 1 . . . . Application n
MHP
API
Interaction
Channel
Broadcast
Channel
Application Manager APIs
(Navigator)
Transport Virtual Machine
Protocols
MPEG Processing
Graphics
I/O Devices Memory
CPU
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.
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 Object
Carousels
Carrusel de objetos
DSMCC Object
Carousels
UDP
UDP
IP
IP
DSMCC Data
Multiprotocol
Carrusel de Carousels
datos
Encapsulation
Encapsulación
multiprotocolo
MPEG-2 Sections
MPEG-2 transport stream
Broadcast channel
DVB-SI
Información
de servicio
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.
MHP: Return Channel

TCP/IP and service-specific protocols for the return channel.
Aplicaciones
Applications
MHP
API
APIs
DSM-CC
Carrusel
de objetos
User-to-User
UNO-RPC/
UNO-CDR
Carrusel de datos
TCP
UDP
HTTP/
HTTPS
IP
UDP
Encapsulación
multiprotocolo
Secciones
IP
MPEG-2
Network
Flujo de dependant
transporte protocols
MPEG-2
Canal
Return
dechannel
difusión
Información
Service
de servicio
specific
protocols
Principles of the Architecture
Structure of the Courses
Course
Manager
Pedagogical
unit
Pedagogical
unit
Pedagogical
unit
Pedagogical
unit
Unit
Manager
Scene
Scene
Element
Element
Element
New Spatial Distribution
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.
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.
Unit
template
Templates
repository
Fully-specified unit
XML
file
Runtime
configuration
Bla, bla, bla,
bla, bla, bla,
bla, bla, bla.
1
2
3

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.
Implementation
Details
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
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.
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.
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.
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.
JXTA: Broadacst Relays
• JXTA super-peers to deal with heterogeneous networks.
• We use them to connect broadcast and IP networks.
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.
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.
Time
Context
Text
Add temporal stamp
New
Load
Save as
Summary and Future Work
Conclusions
• Human and technical factors advice against direct
translation of e-learning solutions.
• Essential distinction between user-driven and mediadriven 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.
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.
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Desarrollo de una arquitectura software para aplicaciones