Experiences with a dialog-driven process model for Web application development

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

Switch or Struggle: Risk Assessment for Late Integration of COTS Components

The domain requirements of software projects often seem so specialized to developers that their original design does not incorporate any commercial-off-the-shelf (COTS) components. However, if major implementation problems are encountered at a later stage in the project, the integration of a COTS component that promises to solve those problems may become a desirable alternative to struggling on with the original implementation. While a number of methods and criteria have already been proposed for requirements engineering, risk assessment and candidate selection of COTS components, they were developed for application in the initial phases of a project and thus do not take into account the much tighter time and design constraints imposedin a later project stage. To spark discussion on necessary adaptations of the established methods, this position paper uses the example of a concrete project to illustrate the characteristics of “switch or struggle” situations and proposes an initial set of risk factors to be considered at that time

Efficient Modeling of Hierarchical Dialog Flows for Multi-Channel Web Applications

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 interface

Cost and Response Time Simulation for Web-based Applications on Mobile Channels

When considering the addition of a mobile presentation channel to an existing web-based application, a key question that has to be answered even before development begins is how the mobile channel’s characteristics will impact the user experience and the cost of using the application. If either of these factors is outside acceptable limits, economical considerations may forbid adding the channels, even if it would be feasible from a purely technical perspective. Both of these factors depend considerably on two metrics: The time required to transmit data over the mobile network, and the volume transmitted. The PETTICOAT method presented in this paper uses the dialog flow model and web server log files of an existing application to identify typical interaction sequences and to compile volume statistics, which are then run through a tool that simulates the volume and time that would be incurred by executing the interaction sequences on a mobile channel. From the simulated volume and time data, we can then calculate the cost of accessing the application on a mobile channel

Fine-Grained Specification and Control of Data Flows in Web-based User Interfaces

When building process-intensive web applications, developers typically spend considerable effort on the exchange of specific data entities between specific web pages and operations under specific condi- tions, as called for by business requirements. Since the WWW infrastructure provides only very coarse data exchange mechanisms, we introduce a notation for the design of fine-grained conditional data flows between user interface components. These specifications can be interpreted by a data flow controller that automatically provides the data entities to the specified receivers at run-time, relieving developers of the need to implement user interface data flows manually

Automatic Dialog Mask Generation for Device-Independent Web Applications

When building web applications for use on different devices, developers need to deal with a wide range of input/output capabilities that affect how users interact with the application: A dialog that can be completed in one step on a desktop client may have to be broken up into a number of steps on a small-screen mobile device. Since it is time-consuming to define all the possible dialog masks and dialog flow variants for different channels manually, it would be desirable to automate the adaptation of dialog masks and flows. To address this need, we introduce the DiaDef language for the abstract, device-independent definition of the widgets in a dialog, and the DiaGen framework that automatically breaks this abstract dialog definition down into sufficiently small dialog masks for the users’ mobile devices and incorporates them into suitable micro dialog flows that are generated at run-time in order to be handled by our Dialog Control Framework

Performance tuning and cost discovery of mobile web-based applications

When considering the addition of a mobile presentation channel to an existing web-based application, project managers should know how the mobile channel|s characteristics will impact the user experience and the cost of using the application, even before development begins. The PETTICOAT (Performance Tuning and cost discovery of mobile web-based Applications) approach presented here provides decision-makers with indicators on the economical feasibility of mobile channel development. In a nutshell, it involves analysing interaction patterns on the existing stationary channel, identifying key business processes among them, measuring the time and data volume incurred in their execution, and then simulating how the same interaction patterns would run when subjected to the frame conditions of a mobile channel. As a result of the simulation, we then gain time and volume projections for those interaction patterns that allow us to estimate the costs incurred by executing certain business processes on different mobile channels

Cost Simulation and Performance Optimization of Web-based Applications on Mobile Channels

When considering the addition of a mobile presentation channel to an existing web-based application, a key question that has to be answered even before development begins is how the mobile channel's characteristics will impact the user experience and the cost of using the application. If either of these factors is outside acceptable limits, economical considerations may forbid adding the channels, even if it would be feasible from a purely technical perspective. Both of these factors depend considerably on two metrics: The time required to transmit data over the mobile network, and the volume transmitted. The PETTICOAT method presented in this paper uses the dialog flow model and web server log files of an existing application to identify typical interaction sequences and to compile volume statistics, which are then run through a tool that simulates the volume and time that would be incurred by executing the interaction sequences on a mobile channel. From the simulated volume and time data, we can then calculate the cost of accessing the application on a mobile channel, and derive suitable approaches for optimizing cost and response times

Specifying and controlling multi-channel web interfaces for enterprise applications

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

Modeling Web-based dialog flows for automatic dialog control

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