Stefan Pietschmann

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

CroCo: Ontology-Based, Cross-Application Context Management

Context-awareness is a key issue for future applications within heterogeneous and networked environments. In terms of efficiency and reusability, such applications should be separated from the problems of context gathering and modeling, but should instead profit from and contribute to cross-application context information. For this purpose, an ontology-based, cross-application context modeling and management service is needed to provide appropriate support for the variety of conceivable application scenarios. Although there have been numerous approaches dealing with application-independent context management, none of them sufficiently supports the vision of cross-application context handling. Therefore, we present CroCo, an ontology-based context management service that allows for cross-application context gathering, modeling, and provision. We verified and tested the practicability of our concept within two different projects with disparate application scenarios.

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.

Using the AMACONT architecture for flexible adaptation of 3D web applications

Providing personalized content and applications which also address heterogeneous capabilities of multiple device types becomes a significant challenge of todays Web development. By now most of the work in the field of adaptive hypermedia is devoted to Web content such as hypertext, images, video, and animation, but rarely to three-dimensional graphics. Research on the adaptation of 3D graphics is still in its infancy. The generic approach introduced in this paper combines the AMACONT adaptive hypermedia architecture with the component-based 3D document model CONTIGRA to achieve 3D adaptation methods such as parametric, structural, and implicit rule-based adaptation as well as rich hypermedia adaptation across media boundaries. In addition a layered context modeling framework supports not only personalization, but also adaptation to device and other contexts. It is shown that the approach can be generalized to other XML-based 3D document formats, e.g. X3D.

Complementary assistance mechanisms for end user mashup composition

Despite several efforts for simplifying the composition process, learning efforts required for using existing mashup editors to develop mashups remain still high. In this paper, we describe how this barrier can be lowered by means of an assisted development approach that seamlessly integrates automatic composition and interactive pattern recommendation techniques into existing mashup platforms for supporting easy mashup development by end users. We showcase the use of such an assisted development environment in the context of an open-source mashup platform Apache Rave. Results of our user studies demonstrate the benefits of our approach for end user mashup development.

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.

Application composition at the presentation layer: alternatives and open issues

The concept of application composition at the presentation layer, i.e., the development of web applications with user interfaces (UI) starting from stand-alone, reusable components, is a relatively new research area. The recent advent of web mashups and component-based web applications has produced promising results, but we argue that there is still a lot of space for improvement. By looking at three advanced approaches in this area, we investigate the current solution space and consequently unveil challenges and problems still to be solved in order to turn presentation composition into common practice.

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.

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.