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) First International Workshop on Multimedia Interactive Protocols and Systems MIPS 2003 November 18-21, 2003 Napoli (Italy)

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

A Few Words about t-Learning

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

Several major technological approaches have been defined. Several major technological approaches have been defined. The future points towards convergence. The future points towards convergence. Obstacles: networks, interoperability and users. Obstacles: networks, interoperability and users. Currently, the different mediums demand different solutions. Currently, the different mediums demand different solutions. Introduction t-learning m-learning e-learning Continuous, ubiquitous learning

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

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

Strategies for Interactivity Applications respond to the user’s actions. Applications respond to the user’s actions. Typical in e-learning services. Typical in e-learning services. The evolution of pieces of media guides users and controls the flow of applications. The evolution of pieces of media guides users and controls the flow of applications. Main option for t-learning. Main option for t-learning. User-driven Media-driven

The MHP Standard

The Multimedia Home Platform Published by the DVB (Digital Video Broadcasting) Consortium in February, Published by the DVB (Digital Video Broadcasting) Consortium in February, It defines a neutral framework for IDTV applications and services. It defines a neutral framework for IDTV applications and services. Increasingly popular among broadcasters and relevant enterprises. Increasingly popular among broadcasters and relevant enterprises. Initially European ones. Initially European ones. The recent GEM (Globally Executable MHP) specification prepares the way into the USA and Japan. The recent GEM (Globally Executable MHP) specification prepares the way into the USA and Japan.

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

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

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

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

Principles of the Architecture

Structure of the Courses SceneScene Element UnitManager Pedagogical unit Pedagogical unit Pedagogical unit Pedagogical unit CourseManager

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

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

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

Templates (II) Templates are configured during runtime. Templates are configured during runtime. Not at design time. Not at design time. The cost of runtime configuration is masked by latencies and loading times. The cost of runtime configuration is masked by latencies and loading times. XML file Templates repository Runtimeconfiguration Unittemplate Bla, bla, bla, bla, bla, bla, bla, bla, bla. 132 Fully-specified unit

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

Implementation Details

Design Goals No need of programming knowledge. No need of programming knowledge. Flexibility and support for all the phases of development. Flexibility and support for all the phases of development. Based on free, open technologies. Based on free, open technologies. Low cost. Low cost. Extensibility. Extensibility. Interoperability. Interoperability.

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

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

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

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

Summary and Future Work

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

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

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