Martín López Nores Department of Telematic Engineering University of Vigo (Spain)

1. First International Workshop on Multimedia Interactive Protocols and Systems MIPS 2003 November 18-21, 2003 Napoli (Italy) A Mixed XML-JavaBeans Approach to Developing t-Learning Applications for the Multimedia Home Platform Martín López Nores Department of Telematic Engineering University of Vigo (Spain)

2. Organization • Introduction to t-learning. • The MHP standard. • Solutions for broadcast services. • Implementation details. • Summary and future work.

3. A Few Words about t-Learning

4. Introduction • A lot of work is being done on distance learning. • In order to overcome the limitations of traditional learning. • Access to education is considered key to maintain a region’s competitiveness.

5. t-learning Continuous, ubiquitous learning e-learning m-learning 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.

6. t-Learning’sAdvantages... • 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.

7. ... 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).

8. 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.

9. The MHP Standard

10. 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. • Increasingly popular among broadcasters and relevant enterprises. • Initially European ones. • The recent GEM (Globally Executable MHP) specification prepares the way into the USA and Japan.

11. Communication Issues • Communication in IDTV is highly assymetric. • Broadcast networks and (optional)return channels. • The MHP framework: • MPEG-2 transport streams for broadcasting live audio and video, and DSM-CC object carrousels for other resources. • TCP/IP and service-specific protocols for the return channel. • The availability of a return channel determines the interactive capabilities. • Simulated and real interactivity.

12. The Object Carrousel • 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.

13. The Problem of Latencies • Latencies can be extremely annoying. • Example: • 520 KB @ 256 Kbps = ¡ 16 seconds per cycle ! • Nobody would wait so long for a program to start. • MHP offers several ways to control latencies: • Caching, preloading and asynchronous loading of contents. • Other contributions: • Adequate planning of the carrousels. • Careful construction of the applications.

14. The MHPProfiles • MHP defines several receiver profiles. • Features and cost tailored to the services required. • We pay special attention to broadcast services. • Inexpensive and fast to develop. • Suitable for edutainment. • Interactivity may drive users towards more active profiles in their use of TV. Extensions for e-mail and web browsing Return channel for real interactivity Enhanced broadcast Internet access Interactive broadcast Simulated interactivity

15. Principles of the Architecture

16. Course Manager Pedagogical unit Pedagogical unit Pedagogical unit Pedagogical unit Unit Manager Scene Scene Element Element Element Structure of the Courses

17. 1 2 3 Conditional Access • Units have a locked/unlocked state. • Can be changed in response to any event. • The composition of a course is summed up in a directed graph, defining • The ordering of the units. • The access dependencies. • This information must be available at the receivers. • Local take of decisions.

18. Contextual Binding • A simple and effective solution for the synchronization of multiple sources of information. • Including the broadcast streams (media-driven units). • It is 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.

19. Templates (I) • Templates are a common feature in many development tools. • Make development tasks faster. • Enhance software reuse. • Help to separate content from graphical appearance. • Their use in IDTV applications offers additional advantages.

20. Templates repository Unit template Bla, bla, bla, bla, bla, bla, bla, bla, bla.  Fully-specified unit Runtime configuration XML file 1 2 3 Templates (II) • Templates are configured during runtime. • Not at design time. • The cost of runtime configuration is masked by latencies and loading times.

21. Templates (III) • The object carrousel transports • the Java class file of the template, • much smaller XML configuration files. • Advantages: • More files can be kept in the cache. • Higher efficiency. • The size of the carrousel decreases. • Lower round-trip time lower latencies.

22. ImplementationDetails

23. 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.

24. Applications programmed in Java. Two main restrictions: MHP APIs. Xletlifecycle. A declarative language, based on Internet standards. XHTML, CSS, cookies, etc. Types of Applications DVB-J DVB-HTML

25. Foundational Technologies: XML • A standard syntax for • the composition of the courses, • the configuration files for a template, • the definition of contexts in the different types of information. • Also used when assembling pedagogical units. • To communicate with content-management systems. • SCORM, IMS, etc.

26. 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.

27. A CASE Tool for t-Learning • We have implemented our approach on top of the NetBeans Platform. • Features: • Entirely visual development. • Simple assembling of pedagogical units. • By retrieving content from repositories or creating it ad-hoc. • Several wizards and assistant tools. • To define the composition of the courses. • For the automatic creation of multiple-choice tests. • To delimit contexts in the different types of information. • Automatic generation of the transport streams.

29. Summary and Future Work

30. Main Conclusions • Human and technical factors advice against direct translation of e-learning solutions. • Broadcast services are essential at an initial stage. • Preparing the way towards highly-interactive services. • The MHP standard provides a satisfactory platform. • Simulated interactivity. • Latencies. • Predominance of multimedia contents. • Essential distinction between user-driven and media-driven strategies.

31. Future Work • Exploit the power of the return channel. • Real interactivity with applications and other users. • Personalization of contents. • Creation of virtual learning communities, involving people with shared interests. • Analyze new multimedia formats: MPEG-4.

32. End