Martin Nussbaumer

A modeling approach to federated identity and access management

As the Web is increasingly used as a platform for heterogeneous applications, we are faced with new requirements to authentication, authorization and identity management. Modern architectures have to control access not only to single, isolated systems, but to whole business-spanning federations of applications and services. This task is complicated by the diversity of todays specifications concerning e.g. privacy, system integrity and distribution in the web. As an approach to such problems, in this paper, we introduce a solution catalogue of reusable building blocks for Identity and Access Management (IAM). The concepts of these blocks have been realized in a configurable system that supports IAM solutions for Web-based applications.

CSS Code Quality: A Metric for Abstractness; Or Why Humans Beat Machines in CSS Coding

Authoring CSS is a complex, time consuming task requiring not only skilled human graphic designers but also skilled human coders. Practice shows that today human authored code is still superior to machine generated CSS, but the code characteristics which make the difference have not been researched or even quantified yet. In this paper we introduce the abstractness factor, a quality metric which reveals the advantages of human authored code and can serve as an optimization criterion and benchmark for automated CSS coding. We argue that a high abstractness factor represents a high maintainability and reusability of the presentation document as well as the content document. By an evaluation of 100,000 HTML pages randomly gathered from the Web we show that today’s typical style sheet document has a significantly higher abstractness factor compared to code fully machine generated by state-of-the-art applications.

Cascading style sheets: a novel approach towards productive styling with today's standards

In this paper we present an approach of generating Cascading Style Sheet documents automatically if the desired effect on the content elements is specified. While a Web user agent resolves the CSS rules and computes their effect, our approach handles the way back. We argue, that this can remarkably improve CSS productivity, since the process of CSS authoring always involves this direction implicitly. Our approach claims a new and innovative way to reuse chunks of markup together with its presentation. It furthermore bears potential for the optimization and reorganization of CSS documents. We describe criteria for CSS code quality we oriented on, including a quantitative indicator for the abstractness of a CSS presentation specification. An evaluation and recomputation of the CSS for 25.000 HTML documents shows that concerning these criteria the automatically generated code comes close to manually authored code.

WCAG formalization with W3C standards

Web accessibility consists on a set of checkpoints which are rather expensive to evaluate or to spot. However, using W3C technologies, this cost can be clearly minimized. This article presents a W3C formalized rule-set version for automatable checkpoints from WCAG 1.0.

FACIUS: An Easy-to-Deploy SAML-based Approach to Federate Non Web-Based Services

Federated identity management yields many advantages such as enhanced usability and improved quality of identity information. Web-based services are already successfully and widely federated using the Security Assertion Markup Language (SAML). In terms of usability and quality of identity information non web-based services benefit from being federated in a similar way web-based services do. However, up to this point no versatile approach that can be easily integrated has emerged to federate them. In this paper, we present FACIUS, an architecture that enables the integration of non web-based services into SAML-based federations. FACIUS aims at minimizing the integration effort in terms of both usability and necessary adjustments to existing service deployments. Furthermore, to prove the practicability of the proposed architecture, we present an implementation to federate SSH services.

Building blocks for identity federations

Technologies like XML and Web Services have posed new requirements to authentication, authorization and identity management for the Web as an application platform. Beyond merely providing access control for a single isolated system, modern, flexible architectures support a business-spanning federation of applications and services by sharing digital identities. The diversity of todays specifications and the many aspects to be considered, like e.g. privacy, system integrity and distribution in the Web, makes the construction of these architectures a very time-consuming task. Thus, a uniform view on the overall system is needed that abstracts from technological issues. This can be achieved by extracting the core concepts from the emerging Federation technologies and specifications and formalize them to an extent that they can be used as a foundation for configurable applications and services. In this paper, we introduce a solution catalogue of reusable building blocks for Identity and Access Management (IAM). We also present a configurable system that supports IAM solutions in Web-service-based applications.

Towards DSL-based web engineering

Strong user involvement and clear business objectives, both relying on efficient communication between the developers and the business, are key factors for a projects success. Domain-Specific Languages (DSLs) being simple, highly-focused and tailored to a clear problem domain are a promising alternative to heavy-weight modeling approaches in the field of Web Engineering. Thus, they enable stakeholders to validate, modify and even develop parts of a distributed Web-based solution.

Beyond the Web Graph: Mining the Information Architecture of the WWW with Navigation Structure Graphs

Large Web sites contain a plethora of different menus and navigation aids, which implement systems of content organization as hierarchies, linear structures or matrices. Humans are able to decode the fine-grained content organization because they are aware of the different access methods provided by navigation systems and understand the higher-level information architecture. In contrast, current methods of link analysis cannot extract such a detailed model of the information architecture and are not able to recognize site boundaries and content hierarchies the way humans do. In this paper present a new approach of mining navigation systems that increases the precision of Web structure mining. Instead of analyzing the complete Web graph spanned by pages and hyperlinks, sub graphs called Navigation Structure Graphs (NSGs) are analyzed. A NSG represents the hyperlinks belonging to a certain navigation system. We demonstrate the capabilities of NSGs for analyzing the organization of Web sites and present our research on mining NSGs.

A domain-specific language for the model-driven construction of advanced web-based dialogs

Complex dialogs with comprehensive underlying data models are gaining increasing importance in todays Web applications. This in turn accelerates the need for highly dynamic dialogs offering guidance to the users and thus reducing cognitive overload. Beyond that, requirements from the fields of aesthetics, Web accessibility, platform-independence, and Web service integration arise. To this end, we present an evolutionary, extensible approach for the model-driven construction of advanced dialogs. It is based on a Domain-specific Language (DSL) focusing on simplicity and fostering collaboration with stakeholders.

Stakeholder collaboration: from conversation to contribution

Establishing efficient and intensive stakeholder collaboration is a key factor in Web application development projects. Therefore, the form of collaboration needs to be shifted from simple conversation to valuable contribution, i.e. empowering stakeholders to directly contribute to the development effort. To achieve this, we introduce an approach combining Domain-specific Languages and an underlying technical platform.