Carlos de Salles Soares Neto

Ginga-NCL: Declarative middleware for multimedia IPTV services

This article presents the innovative features of Ginga-NCL, an open middleware specification for multimedia IPTV services. Ginga-NCL relies on the Nested Context Language, a domain-specific declarative language targeting multimedia application authoring. As a glue language, NCL relates media objects in time and space without restricting or imposing any media content type, including media objects with imperative and declarative code written using other languages. Other NCL features include support for multidevice presentations, content adaptations, presentation adaptations, and advanced code reuse. Ginga-NCL allows NCL applications to be modified on the fly by means of live editing commands. Initially defined as the standard middleware for the Brazilian terrestrial DTV system, Ginga-NCL has recently become part of ISDB standards and an ITU-T Recommendation for IPTV services.

The Nested Context Language reuse features

NCL, the standard declarative language of the Brazilian Terrestrial Digital TV System and ITU-T Recommendation for IPTV Services, provides a high level of reuse in the design of hypermedia applications. In this paper we detail how its design and conceptual model have succeeded in supporting reuse at a declarative level. NCL supports not only static but also running code reuse. It also allows for reuse inside applications, reuse between applications, and reuse of code spans stored in external libraries. For a specification language to promote reuse, however, it must have a number of usability merits. Aspects of NCL usability are thus analyzed with the Cognitive Dimensions of Notation framework.

TAL—Template Authoring Language

This paper presents TAL (Template Authoring Language), an authoring language for hypermedia document templates. Templates describe document families with structural or semantic similarities among them. TAL supports the description of templates independently of the target hypermedia authoring language. The paper also presents a TAL processor that generates complete hypermedia documents taking as input a template specification in TAL and a data file with the information that makes that document particular in its family.

Textual authoring of interactive digital TV applications

Authoring tools for hypermedia languages usually provide visual abstractions, which hide the source code from the author aiming to simplify and accelerate the development process. Among other drawbacks, these abstractions modify or even break the communication process between the author and the language designer, since these languages were designed to be readable and understandable by its target audience. This paper presents a textual approach to hypermedia authoring that does not have these inconveniences, but rather uses typographical accessories, such as program visualization, hypertextual navigation, and semi-automatic error correction. The proposed approach exploits concepts known to the author and does not imply in extra cognitive overload. A use case is presented, namely the NCL Eclipse authoring environment, for Nested Context Language, the Brazilian Digital TV and ITU-T standard.

A visual approach for modeling spatiotemporal relations

Textual programming languages have proven to be difficult to learn and to use effectively for many people. For this sake, visual tools can be useful to abstract the complexity of such textual languages, minimizing the specification efforts. In this paper we present a visual approach for high level specification of spatiotemporal relations. In order to accomplish this task, our visual representation provides an intuitive way to specify complex synchronization events amongst media. Finally, to validate our work, the visual specification is mapped to NCL (Nested Context Language), the standard declarative language of the Brazilian Terrestrial Digital TV System.

TAL processor for hypermedia applications

TAL (Template Authoring Language) is a specification language for hypermedia document templates. Templates describe application families with structural and semantic similarities. In TAL, templates not only define design patterns that applications must follow, but also constraints on the use of these patterns. A template must be processed together with a padding document giving rise to a new document in some specification language, called target language. TAL supports the description of templates independently of the languages used to specify target and padding documents. Usually a specific processor is required for each target language and for each padding document used. This paper concerns TAL processors. However, we should note that the proposal can be easily extended to any other solution used to define templates. Any pattern language and any language used to define constraints could be used instead of TAL. The TAL processor architecture is general and it is discussed when presenting the processor framework. As an instantiation example, an implementation of a TAL Processor targeting NCL (the declarative language of Ginga DTV middleware) is examined, and also another one targeting HTML-based middleware. The use of wizards for defining padding documents is also discussed in the examples of the proposed architecture instantiation.

Architectural description of QoS provisioning for multimedia application support

The increasing number of multimedia applications has motivated the construction of platforms with end-to-end quality of service (QoS) support. This work proposes the use of Wright architecture description language (ADL) in the QoS provisioning domain, as the basis for the formal verification of QoS system properties. To smooth this task, the LindaQoS domain-specific language was designed as a high-level notation for the specification of resource (QoS) orchestration. As a result of this approach, we expect that designers can define clear and unambiguous instantiated platforms, with support to multimedia application implementations, in a reduced development time.

Cacuriá: Authoring Tool for Multimedia Learning Objects

The application of multimedia resources during classes is becoming increasingly usual, making the learning process more participatory and interactive. Learning Objects (LOs) are entities, digital or not, that can be used, reused or referenced during teaching process. The multimedia authoring of LOs is still a complex and time-consuming process. The purpose of this paper is to present the process of participatory design used in the development of Cacuriá, a tool that allows teachers and tutors to create and share videos enriched with interactive multimedia contents. Cacuriá interface was developed using Participatory Design techniques, including focus group, Card Sorting and Paper Prototyping followed by an enhancement of the interface design. This paper also describes implementation architecture of Cacuriá. Finally, a case study was conducted to present a possibility of OAs creation using the Cacuriá Tool without requiring the user to previously knowing programming concepts.

Architecture for hypermedia dynamic applications with content and behavior constraints

This paper deals with the generation of dynamic hypermedia applications whose content and behavior their authors may not be able to predict a priori, but which must conform to a strict set of explicitly defined constraints. In the paper, we show that it is possible to establish an architecture configuration to be followed by this special kind of dynamic applications. In the proposed architecture, templates are responsible for specifying the design patterns and the constraints to be followed. Some alternatives for distributing (from the client side to the server side) the components that comprise the architecture are discussed, and one of them is used to exemplify an instantiation of the architecture. In the instantiation, TAL (Template Authoring Language) is used to define templates. In TAL, templates are open-compositions, that is, especial set of patterns for compositions, whose content must obey some explicitly defined constraints. The paper also shows how the architecture instantiation could be used to build dynamic digital TV applications.

An approach for textual authoring of hypermedia documents based on the use of programmatic visualization and hypertextual navigation

Authoring tools for hypermedia languages often provide visual abstractions that hide the source code from the author with the objective of simplifying and accelerating the development process. Among other drawbacks, these abstractions modify or even prevent the communication process between the author and the designer of the language, which has been designed to be streamlined and readable by its target audience. This paper presents a textual approach to hypermedia authoring that does not inherit these inconveniences, but also makes use of typographical accessories such as programmatic views and hypertextual navigation. By setting an environment for hypermedia authoring similar to the presentation engine of the source language, the proposed approach uses concepts known by the author and does not imply in cognitive overload. A case of use is exemplified by the NCL Eclipse authoring environment, toward for Nested Context Language, the standard for the Brazilian Digital TV System.