Klaus Meißner

Contigra: an XML-based architecture for component-oriented 3D applications

Even though numerous Web3D technologies exist, most of them do not support a high-level, multi-disciplinary authoring process. Moreover, concepts of reuse are rarely provided. A component-based approach is introduced with the CONTIGRA architecture to construct interactive, three-dimensional applications, either stand-alone or web-based. The approach is entirely based on declarative XML documents describing the component imple¿mentation, its interface, as well as component configuration and composition of 3D user interfaces and virtual environments. Extensible 3D (X3D) is used as the scene graph basis. However, the resulting applications can be translated to other 3D tech¿nologies, too. Another advantage of the approach is reuse both at the implementation level and the higher abstract component level. This paper introduces the overall architecture and the XML schemas used for the component documents. It finally outlines the associated authoring process and tools involved.

CRUISe: Composition of Rich User Interface Services

As reuse and technology-independence are key issues of both software and web engineering, web services have gained momentum and are heavily used in modern web-based applications. However, they are only expedient for the business logic layer, while the Web lacks uniform models for the encapsulation and reuse of UI components. Thus, web UIs are usually hand-crafted and static, which complicates both development as well as maintenance and upgrade. We address these issues with a novel approach facilitating dynamic, service-oriented composition of user interfaces for web applications. UI parts therein are provided as reusable services and can therefore be selected, customized and exchanged dynamically with respect to a particular context

A metamodel for context-aware component-based mashup applications

Recently, mashups, i.e., composite web applications, have gained momentum in both the consumer and enterprise sector. However, they lack a structured development process which abstracts from specific platforms and enables a universal composition including the presentation layer. Moreover, support for context-awareness in such applications has been neglected so far. Yet, it becomes increasingly necessary due to the growing heterogeneity of users and devices. We address these issues by proposing an open, extensible metamodel for component-based mashup applications. It defines their control flow, layout, and adaptivity while building on lessons learned from traditional web application models. This metamodel forms the basis for a structured, model-driven development process entailing reusability and independence from specific composition platforms. We implemented the metamodel and successfully proved its practicability with a number of exemplary applications deployed on different platforms.

A Semantics-Based, End-User-Centered Information Visualization Process for Semantic Web Data

Understanding and interpreting Semantic Web data is almost impossible for novices as skills in Semantic Web technologies are required. Thus, Information Visualization (InfoVis) of this data has become a key enabler to address this problem. However, convenient solutions are missing as existing tools either do not support Semantic Web data or require users to have programming and visualization skills. In this chapter, we propose a novel approach towards a generic InfoVis workbench called VizBoard, which enables users to visualize arbitrary Semantic Web data without expert skills in Semantic Web technologies, programming, and visualization. More precisely, we define a semantics-based, user-centered InfoVis workflow and present a corresponding workbench architecture based on the mashup paradigm, which actively supports novices in gaining insights from Semantic Web data, thus proving the practicability and validity of our approach.

Dynamic Composition of Service-Oriented Web User Interfaces

So far, little research has addressed reuse and context awareness with respect to rich web-based user interfaces. Uniform models for encapsulation and reuse have been developed for the applications’ back ends in the form of Web Services, but this paradigm has not yet been applied to the presentation layer. Thus, UIs are usually hand-crafted and lack flexibility and reuse, which makes their development time- and money-consuming. We address these issues with a system facilitating dynamic, service-oriented composition of user interfaces for modern web applications. UI parts are provided “as-a-service” and can thus be selected, customized and exchanged with respect to the current context.

Harnessing the Power of Semantics-Based, Aspect-Oriented Adaptation for amacont

Adaptivity in web applications raises several concerns. One demands it to be decoupled from the actual application and at the same time wants to use very domain-specific terms for dividing the audience into groups. Two current trends, aspect-oriented programming and semantic web technologies, fit these requirements like a glove. In this paper, we present the Amacont web modeling framework and use it as an example of how to extend such a framework to make use of these powerful technologies. The underlying concepts, however, can be applied to the modeling of adaptivity in general.

CapView: functionality-aware visual mashup development for non-programmers

Building mashup applications from existing web resources becomes increasingly popular, and, in theory, accessible even for end users without programming skills. Current proposals for end user development of mashups mainly focus on visual wiring of component interfaces supplemented by recommendations on composition steps and a certain degree of automation. However, it is still a major challenge to provide an appropriate level of functional abstraction in order to visualize the functionality of a mashup and its components, and for composing on a functional level instead of merely assembling structural units. This becomes crucial, especially when non-programmers are the intended target group. In this paper, we propose CapView, a novel functionality-aware development view on running composite applications. CapView is part of the EDYRA platform and provides a functional overview of the mashup by abstracting from interface and wiring details. It enables users to understand mashup development as an assembly process that is centered on the capabilities of components and mashup fragments. We evaluate the concepts in a user study and present lessons learned.

Weighted faceted browsing for characteristics-based visualization selection through end users

Faceted browsing is a widely spread, intuitive, and interactive search paradigm for information collections based on the metadata of its items. However, it has the problem that every selected criterion is mandatory so that less important ones may reduce the result set and interesting items may be removed unintentionally. On the other hand, choosing only very few facets yields to an unmanageable set of items wherein the best ones do not become obvious. In this paper, we propose weighted faceted browsing, which seamlessly extends the existing faceted browsing paradigm. Besides basic filtering capabilities, it provides a sophisticated relevance ranking of the result set based on the distinction between mandatory and weighted optional search criteria. Further, we show its practicability within an information visualization workbench to facilitate the end users search for visualization components based on their characteristics.

Task-Based recommendation of mashup components

Presentation-oriented mashup applications are usually developed by manual selection and assembly of pre-existent components. The latter are either described on a very technical, functional level, or using informal descriptors, such as tags, which bear certain ambiguities. With regard to the increasing number and complexity of available components, their discovery and integration has become a challenge for non-programmers. Therefore, we present a novel concept for the task-based recommendation of mashup components, which comprises a more natural, task-driven description of user requirements and a corresponding semantic matching algorithm for universal mashup components. By its realization and integration with an composition platform, we could prove the feasibility and sufficiency of our approach.

A Thin-Server Runtime Platform for Composite Web Applications

Mashups propose a lightweight integration of applications by combining distributed web resources. Their development is aided by a number of visual tools and platforms. However, they all imply a server-side mashup execution. Since data, application logic, and UI can all be provided as a service, we argue that the client can be the ideal integration platform for such applications. In this paper we highlight challenges and requirements of such a thin-server composition and execution system and propose a corresponding architectural concept to integrate back-end as well as front-end services of a composite application within the browser. We further present an implementation of our concept and validate its practicability by means of a sample application.