This paper discusses the importance of non-functional requirements in the design of hypermedia authoring tools, which typically provides multiple graphical abstractions (views). It focuses on creating products and services that operate robustly across a broad range of environments, and that take into account the changeable needs of their users over time, as they become more familiar with the tool. In order to meet these non-functional aspects, this paper proposes a microkernel-based architecture for authoring tools, where the microkernel is responsible for instantiating the requested extensions (plugins), maintaining the core data model that represents the hypermedia document under development, and notifying changes in this model to plugins interested in them. Based on the proposed architecture, a new version of Composer (an NCL authoring tool) is presented, rewritten from scratch. Results from experiments show that the discussed non-functional requirements are adequately met.

Composer: meeting non-functional aspects of hypermedia authoring environment

Modelling and transposition of location-based games

This paper presents the concept of eventline as a visual representation proposal for the temporal behavior of multimedia applications. The main difference of this proposal when compared to the timeline paradigm is the replacement of the temporal continuous axis to a temporal discrete axis based on the occurrence of events. Media synchronization in each eventline is based on the relative time of a main media. User interaction is expressed as the navigation between multiple eventlines. The objective of this work is to provide a simplified alternative for authoring of interactive multimedia applications.

Eventline: representation of the temporal behavior of multimedia applications

This paper presents an incremental validation process for multimedia documents describing interactive digital TV (iTV) applications. This work delves more specifically into documents defined in Nested Context Language (NCL), a declarative language standard adopted by ISDB-Tb and ITU-T for IPTV. The focus of incremental validation, the approach proposed in this work, relies on checking only the pieces of code that have been modified since the latest validation as well as those parts that have suffered any side effects, thus eliminating the need for a thorough checking of the document. The implications of performing this type of validation in a declarative language such as NCL are discussed and implementation details are given. Performance tests comparing the standard and incremental validation approaches have been carried out revealing a significant improvement concerning the latter.

Incremental validation of digital TV applications in nested context language

NCL (Nested Context Language) is a notation for hypermedia application authoring, designed to facilitate the modeling and authoring of Digital TV applications for authors with different levels of programming knowledge. However, the ease of use of NCL is questionable due to XML notation and has been the subject of study of several works that analyze its usability while proposing other solutions. This work presents sNCL (simpler NCL), a declarative domain specific language, projected using guidelines established by the CDN (Cognitive Dimensions of Notation) framework applied to NCL. To validate the proposal, an experiment with a questionnaire on the success factors in NCL and sNCL is applied to users with experience in authoring with NCL, comparing their opinions on both languages. The experiment demonstrates that sNCL gains in usability, which can improve, therefore, the performance of authors in the development of applications.

Usability-based Language for Authoring NCL Documents

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.

Thiago Alencar Gomes

Papers

Textual authoring of interactive digital TV applications