Information systems for the support of complex business processes are often equipped with web-based front-ends to allow convenient user access. To produce executable specifications of the users’ interactions with such web-based applications, we use a visual language that enables developers to model their complex dialog structures. In this paper, we introduce the formal semantics of the core constructs of this Dialog Flow Notation: We define its syntax in terms of invariants about the permitted elements and their relations, and show how any words of the language (i.e. any syntactically correct dialog flow specifications) can be mapped to a deterministic pushdown automaton whose behavior defines the notation’s semantics. This gives us and other tool developers a formal basis for the design and implementation of tools and frameworks that mirror the precise meaning of all DFN constructs.

The hype surrounding Web 2.0 and technologies such as AJAX shows: The future of distributed application development lies in Rich Internet Applications (RIAs), which are based on highly distributed components and characterized by the intensive use of communication networks, complex interaction patterns and advanced GUI capabilities. As service providers begin to tap into the mobile market by extending the reach of their established e-commerce systems to mobile devices, a core challenge is the choice of a runtime environment and middleware that adapts well to the existing architecture, yet is a safe investment for the years to come. This paper surveys the current state and the future of runtime environments suitable for developing RIAs for mobile clients.

XMach-1 was the first XML data management benchmark designed for general applicability [1]. It is still the only benchmark supporting a multiuser performance evaluation of XML database systems. After a brief review of XMach-1 we summarize three additionally proposed benchmarks (XMark, XOO7, Mbench) and provide a comparison between these benchmarks. We then present experiences and performance results from evaluating XML database systems with XMach-1.

We propose a scaleable multi-user benchmark called XMach-1 (XML Data Management benchmark) for evaluating the performance of XML data management systems. It is based on a web application and considers different types of XML data, in particular text documents, schema-less data and structured data. We specify the structure of the benchmark database and the generation of its contents. Furthermore, we define a mix of XML queries and update operations for which system performance is determined. The primary performance metric, Xqps, measures the query throughput of a system under response time constraints. We will use XMach-1 to evaluate both native XML data management systems and XML-enabled relational DBMS.

We present a new approach for accelerating the execution of XPath expressions using parameterized materialized XPath views (PXV). While the approach is generic we show how it can be utilized in an XML extension for relational database systems. Furthermore we discuss an algorithm for automatically determining the best PXV candidates to materialize based on a given workload. We evaluate our approach and show the superiority of our cost based algorithm for determining PXV candidates over frequent pattern based algorithms.

Today, we are seeing an increasing number of software applications that users want to use anywhere, anytime. Such mobile applications often deliver their user interfaces (UIs) to client devices over the World Wide Web. However, Web-based UIs cannot provide the same level of usability as window-based UIs on mobile devices with their small screens and occasional network dropouts. To address this challenge, we present a UI framework that combines the usability of a full-featured UI with the flexibility of a thin presentation logic: We exchange interface specifications and events between the application logic on the server and a generic UI rendering engine on the client device using an instant messaging infrastructure. The paper gives an overview of the framework architecture and the features of the communication protocol, and discusses performance measurements obtained on a public network.

When building enterprise applications that need to be accessed through a variety of client devices, developers usually strive to implement most of the business logic device-independently while using a web browser to display the user interface. However, when those web-based front-ends shall be rendered on different devices, their differing I/O capabilities may require device-specific interaction patterns that still need to be specified and implemented efficiently. We present an approach for specifying the dialog flows in multi-channel web interfaces with very low redundancy and introduce a framework that controls web interfaces’ device-specific dialog flows according to those specifications, while keeping the enterprise application logic completely device-independent.

In Web-based applications, most user interactions take the form of navigating between Web pages. The structure of the navigation model thus has a strong impact on a Web application's usability. However, specifying a user-friendly navigation model for complex applications can be time-consuming, especially when designing for multiple presentation channels. We therefore present the formal semantics of the dialog flow notation (DFN) that provides constructs for the design of modular navigation models, and especially focus on constructs that reduce the specification redundancy within and between channels, thus reducing the design effort for Web-based user interfaces

We present a dialog-driven process model for the development of web-based applications that uses a graphical notation to model and iteratively refine the application’s dialog flow, and communicate with non-technical stakeholders in the development process. This way, the user interface can drive the design and implementation of the application logic and data model instead of being dictated by it. After an introduction of the underlying notation and dialog control framework, we present how these tools can support the phases of the development process and discuss experiences gained from the implementation of a web application that was built using this approach.

In web-based applications, the dialog control logic is often hidden in or entwined with the presentation and/or application logic, even if the latter tiers are well-separated. This makes it difficult to control complex dialog structures like nested dialogs, and to reconcile the device-independent business logic with the device-specific interaction patterns required by different clients’ I/O capabilities. To avoid continuous re-implementation of the dialog control logic, we present a Dialog Control Framework that is separate from the presentation and business tiers, and manages arbitrarily nested dialog flows on different presentation channels. The framework relies on dialog specifications developed using the Dialog Flow Notation, which are translated into an object-oriented dialog flow model for efficient run-time lookups. This way, the framework automates the dialog control aspect of web-based application development and leaves only the tasks of implementing the business logic, designing the hypertext pages, and specifying the dialog flow to the developer.