Software developers typically use multiple large screens in their office setup. However, they often work away from the office where such a setup is not available, instead only working with a laptop computer and drastically reduced screen real estate. We explore how developers can be better supported in ad-hoc scenarios, for example when they work in a cafe, an airport, or at a client's site. We present insights into current work practices and challenges when working away from the usual office desk sourced from a survey of professional software developers. Based on these insights, we introduce an IDE that makes use of additional personal devices, such as a phone or a tablet. Parts of the IDE can be offloaded to these mobile devices, for example the application that is being developed, a debugging console or navigational elements. A qualitative evaluation with professional software developers showed that they appreciate the increased screen real estate.

The number of smart devices that people own or share with family and friends has increased dramatically. As a result, users often want to copy data among devices such as smart-phones, tablets and desktop computers. While various chat and cloud services support the sharing of data, they require users to interrupt their workflow to copy resources. We present MyoShare, a system that allows content to be shared among devices using mid-air gestures that can be used at any time, independent of the current task and location of devices. We report on an elicitation study where participants designed a set of gestures for sharing content. In a second user study, we compared mid-air gestures with alternative interaction modes using keyboard or touch Shortcuts, Speech, and Menu Selection. We discuss the results of the study in terms of both the strengths and weaknesses of mid-air gestures, along with suggestions for future work.

With the growth of mobile devices, the necessity for a more ubiquitous network among the smartphones, tablets and computers of users increases. Sending and receiving content among personal devices should be an intuitive rather than a distracting task to be performed. With MyoShare, we propose a system that exploits the use of mid-air gestures, captured via the Myo wearable armband, to share web data among devices without requiring the user to open additional windows or copy-paste content into emails or chat applications. Users can select content from any web page and send it to another device by simply waving their hands. During the demo session, participants of the conference will be able to try out and see our system in action.

Tilt-and-Tap (TAT) is a jQuery-like framework that supports the rapid development of web applications that use tilting gestures for interaction. Such gestures enable users to interact with, and navigate through, websites by simply moving their mobile device in combination with screen taps. Building on this, we have also developed a second framework Cross-Tilt-and-Tap (CTAT) that supports the rapid development of applications that use motion-basd gestures in a range of multi-device scenarios. Our demo not only shows a range of applications that we have developed using the frameworks, but also the frameworks in action by demonstrating the steps involved in developing and adapting applications.

The increasing number of devices available to a user has prompted the research community to explore how these can be used in combination. Frameworks and toolkits have been proposed to facilitate the design and implementation of these cross-device applications. Still, implementing cross-device applications remains complex because of the fragmentation of the user interface and logic across devices and the flexibility required to adapt to different combinations of devices. Testing in particular has been identified as a critical challenge. To address these issues, we introduce XD-Testing, a library that provides explicit and implicit device selectors, device templates and scenarios, as well as a visualiser for application screenshots. In a case study, we demonstrate how we used the library to author human-readable tests for a cross-device gallery that verify if a UI distributes correctly and if it works as expected despite being distributed.

Personal cloud services such as Dropbox are used increasingly to support collaborative work, even though they typically have poor support for tracking files and users' activities and collaborators often rely on other communication channels to be notified of changes. We present a meta-cloud storage service, MUBox, that, independent of a particular cloud storage service, provides improved support for collaboration. First, users can switch to activity views that list user activities rather than files, which is an example of an increasingly available feature in popular cloud storage clients. Second, MUBox introduces multi-user aware folder views that embed information on the last changes performed by collaborators. These folder views are enhanced based on a new concept of shadow files which act as placeholders for files that have been moved or renamed. A user study (N=16) with realistic folder exploration tasks shows that activity views have a significant effect on the accuracy and confidence of users in workspace awareness tasks, while shadow files significantly improve the speed, accuracy and confidence of users in traceability tasks. We describe how existing services could implement these features as well as a new concept for voting on changes to shared folders that could improve asynchronous collaboration.

While there are many established methodologies for information systems development, designing by example has not been formally explored and applied previously. Our work is also motivated by the desire to explore interface-driven development techniques that could complement existing approaches such as model-driven engineering with the goal of reducing the need for modelling and reengineering of existing applications and interfaces, while still supporting the development task. We explore the example-based technique for rapid development of powerful and flexible information management tools based on the example of Adobe Photoshop Lightroom, a system that was originally designed to support the workflow of digital photographers in a flexible way. We analyse experiments in which two new systems---one for managing collections of research papers and another for software project management---were developed based on the Lightroom paradigm. We derive a conceptual framework for engineering by example and assess the method by comparing it to traditional model-driven engineering.

Current GUI builders provide a design environment for user interfaces that target either a single type or fixed set of devices, and provide little support for scenarios in which the user interface, or parts of it, are distributed over multiple devices. Distributed user interfaces have received increasing attention over the past years. There are different, often model-based, approaches that focus on technical issues. This paper presents XDStudio--a new GUI builder designed to support interactive development of cross-device web interfaces. XDStudio implements two complementary authoring modes with a focus on the design process of distributed user interfaces. First, simulated authoring allows designing for a multi-device environment on a single device by simulating other target devices. Second, on-device authoring allows the design process itself to be distributed over multiple devices, as design and development take place on the target devices themselves. To support interactive development for multi-device environments, where not all devices may be present at design and run-time, XDStudio supports switching between the two authoring modes, as well as between design and use modes, as required. This paper focuses on the design of XDStudio, and evaluates its support for two distribution scenarios.

We propose the PATRICIA-hypercube-tree, or PH-tree, a multi-dimensional data storage and indexing structure. It is based on binary PATRICIA-tries combined with hypercubes for efficient data access. Space efficiency is achieved by combining prefix sharing with a space optimised implementation. This leads to storage space requirements that are comparable or below storage of the same data in non-index structures such as arrays of objects. The storage structure also serves as a multi-dimensional index on all dimensions of the stored data. This enables efficient access to stored data via point and range queries. We explain the concept of the PH-tree and demonstrate the performance of a sample implementation on various datasets and compare it to other spatial indices such as the kD-tree. The experiments show that for larger datasets beyond 10^7 entries, the PH-tree increasingly and consistently outperforms other structures in terms of space efficiency, query performance and update performance.

Web designers currently face the increased proliferation and diversity of new touch devices which pose major challenges to the design task. This paper presents W3Touch - an interface instrumentation toolkit for web designers to collect user performance data for different device characteristics in order to help them identify potential design problems for touch interaction. Web designers can visualise the data aggregated by W3Touch and use simple metrics to automate the adaptation process for many different viewing and interaction contexts. In a series of experiments with web designers and users, we show that W3Touch is able to detect interaction problems that are hard to find using conventional methods and demonstrate how the tool was successfully used to automate the desktop-to-mobile migration of Wikipedia as an example.

The enormous increase of digital image collections urgently necessitates effective, efficient, and in particular highly flexible approaches to image retrieval. Different search paradigms such as text search, query-by-example, or query-by-sketch need to be seamlessly combined and integrated to support different information needs and to allow users to start (and subsequently refine) queries with any type of object. In this paper, we present QUEST (Query by Example, Sketch and Text), a novel flexible multi-modal content-based image retrieval (CBIR) framework. QUEST seamlessly integrates and blends multiple modes of image retrieval, thereby accumulating the strengths of each individual mode. Moreover, it provides several implementations of the different query modes and allows users to select, combine and even superimpose the mode(s) most appropriate for each search task. The combination of search paradigms is by itself done in a very flexible way: either sequentially, where one query mode starts with the result set of the previous one (i.e., for incrementally refining and/or extending a query) or by supporting different paradigms at the same time (e.g., creating an artificial query image by superimposing a query image with a sketch, thereby directly integrating query-by-example and query-by-sketch). We present the overall architecture of QUEST and the dynamic combination and integration of the query modes it supports. Furthermore, we provide first evaluation results that show the effectiveness and the gain in efficiency that can be achieved with the combination of different search modes in QUEST.

With the proliferation and sophistication of digital reading devices, new means to support the task of active reading (AR) have emerged. In this paper, we investigate the use of pen-and-touch-operated tabletops for performing essential processes of AR such as annotating, smooth navigation and rapid searching. We present an application to support these processes and then report on a user study designed to compare the suitability of our setup for three typical tasks against the use of paper media and Adobe Acrobat on a regular desktop PC. From this evaluation, we found out that pen and touch tabletops can successfully combine the advantages of paper and digital devices without their disadvantages. We however also learn from observations and participant feedback that there are still a number of hardware and software limitations that impede the user experience and hence need to be addressed in future systems.

Although web sites have started to embed semantic metadata within their documents, it remains a challenge for non-technical end-users to exploit that markup to extract and store information of interest. To address this challenge, we show how tools can be developed that allow users to identify extractable information while browsing and then control how that information should be extracted and stored in a personal library. The proposed approach is based on an extensible framework capable of using different kinds of markup to aid the extraction process and a unique fusion of several well-established techniques from areas such as the semantic web, data warehousing, web scraping and web feeds. We present the Sift tool which is a proof-of-concept implementation of the approach.

Despite the fact that screen sizes and average screen resolutions have dramatically increased over the past few years, little attention has been paid to the design of web sites for large, high-resolution displays that are now becoming increasingly used both in enterprise and consumer spaces. We present a study of how the visual area of the browser window is currently utilised by news web sites at different widescreen resolutions. The analysis includes measurements of space taken up by the article content, embedded ads and the remaining components as they appear in the viewport of the web browser. The results show that the spatial distribution of page elements does not scale well with larger viewing sizes, which leads to an increasing amount of unused screen real estate and unnecessary scrolling. We derive a number of device-sensitive metrics to measure the quality of web page layout in different viewing contexts, which can guide the design of flexible layout templates that scale effectively on large screens.

Despite the fact that average screen size and resolution have dramatically increased, many of today's web sites still do not scale well in larger viewing contexts. The upcoming HTML5 and CSS3 standards propose features that can be used to build more flexible web page layouts, but their potential to accommodate a wider range of display environments is currently relatively unexplored. We examine the proposed standards to identify the most promising features and report on experiments with a number of adaptive layout mechanisms that support the required forms of adaptation to take advantage of greater screen real estates, such as automated scaling of text and media. Special attention is given to the effective use of multi-column layout, a brand new feature for web design that contributes to optimising the space occupied by text, but at the same time still poses problems in predominantly continuous vertical-scrolling browsing behaviours. The proposed solutions were integrated in a flexible layout template that was then applied to an existing news web site and tested on users to identify the adaptive features that best support reading comfort and efficiency.

Pen and paper support the rapid production of sketches. However, the paper interface is not always optimal for collaborative sketching as seen in brainstorming sessions where multiple parties would often like to communicate and participate in the sketching synchronously. Novel interactive paper solutions may provide the answer by bridging the paper-digital divide and allowing users to sketch on paper simultaneously while capturing the actions digitally. We present an analysis of collaborative sketching activities in working environments with remote participation. After highlighting the importance of paper for natural interaction in these settings, we introduce PaperSketch, an interactive paper-digital tool for collaborative remote sketching. We discuss the collaborative development of ideas based on the prototype and outline how important feedback issues have been addressed by utilising spatial constraints and multimodal features.

Paper notes are still widely used during meetings for the capture and review of information created in meetings. However, personal notes are limited in terms of providing an overview of collaborative work practices and reflecting the evolution of data along successive meeting phases, especially taki

When involved in collaborative tasks, users often choose to use multi-synchronous applications in order to concurrently work in isolation. Hence, privacy of their changes is maintained until they decide to publish their contributions. Not being aware of changes made by their collaborators, they often create concurrent modifications which might generate conflicts or lead to redundant work. We propose an awareness mechanism that solves this problem by computing and providing awareness in multi-synchronous collaboration while at the same time respecting user privacy by allowing users to specify the detail of information made available to their collaborators. The computation of awareness is based on metrics that measure the effect of changes for the different types of changes, on the different syntactic document levels and document parts. For the visualisation of awareness, we employ the concept of edit profiles.

In most web mashup applications, the content is generated using either web feeds or an application programming interface (API) based on web services. Both approaches have limitations. Data models provided by web feeds are not powerful enough to permit complex data structures to be transmitted. APIs based on web services are usually different for each web application, and thus different implementations of the APIs are required for each web service that a web mashup application uses. We propose a database-driven approach to web mashups that supports integration at the database level and enables mashup developers to work with a uniform abstract model and have direct access to powerful features of database systems. We describe how we have implemented this approach based on an object-oriented database system with a rich object model and a generic proxy mechanism for data integration and synchronisation.

Although awareness is important in collaboration, user studies have shown that many groupware tools fail to meet user requirements or expectations in this respect. We show how richer documents models can lead to richer forms of awareness and present a general awareness framework based on a metamodel for structured documents and associated metrics. We describe how the framework was used to extend a collaborative authoring system to provide awareness information at variable levels of granularity according to user requirements. We also discuss how the framework could be used with other forms of collaborative tools.

Although extensive research has been conducted in recent years to provide awareness information for collaborative authoring in synchronous and semi-synchronous modes, this is not the case for asynchronous collaboration. Users involved in collaborative writing tasks often choose to work in isolation in order to keep their changes private until committed. However, the fact that other users are unaware of these changes can result in unnecessary work being done by other users or conflicts to be resolved. We address this problem and propose a solution based on the notion of Shadow Documents. We monitor in real-time changes made to a document by all users working in privacy in order to compute and present awareness information based on the changes. We present our approach in detail, along with a prototype of a shared workspace for asynchronous collaboration based on Shadow Document Sets.

The first steps towards bridging the paper-digital divide have been achieved with the development of a range of technologies that allow printed documents to be linked to digital content and services. However, the static nature of paper and limited structural information encoded in classical paginated formats make it difficult to map between parts of a printed instance of a document and logical elements of a digital instance of the same document, especially taking document revisions into account. We present a solution to this problem based on a model that combines metadata of the digital and printed instances to enable a seamless mapping between digital documents and their physical counterparts on paper. We also describe how the model was used to develop iDoc, a framework that supports the authoring and publishing of interactive paper documents.

With the emergence of digital pen and paper interfaces, there is a need for gesture recognition tools for digital pen input. While there exists a variety of gesture recognition frameworks, none of them addresses the issues of support- ing application developers as well as the designers of new recognition algorithms and, at the same time, can be inte- grated with new forms of input devices such as digital pens. We introduce iGesture, a Java-based gesture recognition framework focusing on extensibility and cross-application reusability by providing an integrated solution that includes tools for gesture recognition as well as the creation and management of gesture sets for the evaluation and optimi- sation of new or existing gesture recognition algorithms. In addition to traditional screen-based interaction, iGesture provides a digital pen and paper interface.

Recent developments in digital pen and paper solutions enable, not only the digital capture of handwriting, but also paper to be used as an interactive medium that links to digital information and services. We present a tool that builds on technologies for interactive paper to enable PowerPoint presentations to be controlled from printed slide handouts. Furthermore, slides can be easily annotated during presentations by simply drawing on the printed version of the slide. As well as discussing the advantages of such a paper-based interface and initial findings on its use, we describe how we were also able to exploit it to provide a general prototyping tool for interactive paper applications.

Version control systems are widely used to support a group of people working together on a set of documents over a network by merging their changes into the same source repository. The existing versioning systems offer limited support concerning conflict resolution and tracking of user activity. In this paper we propose a multi-level editing approach that keeps the editing operations that refer to an element of a hierarchical document associated with that element. In this way, customisable merging is achieved, where the conflicts can be specified and resolved at different granularity levels

Awareness of the activities of other users and also document evolution is an important part of collaborative authoring. We introduce the concept of an editing profile that can be used to maintain and visualise measures of the changes made across a document by different users in both synchronous and asynchronous collaborative editing. It provides a simple means of making users aware of "hot areas" and also who is or has been active in various parts of the document, as well as a quick access point into parts of the document that have been changed. The profile can be adapted to display the most relevant information based on both user preference and situation

Collaborative object-based graphical editors offer good support for design teams to work concurrently on their design. However, not much research has been done on maintaining consistency when complex operations such as the grouping of objects or working on layers are involved. In this paper, we propose a novel operation serialisation algorithm for consistency maintenance based on the reordering of nodes in a graph. The nodes of a graph represent operations and the edges represent ordering constraints between operations. Users can specify types of conflicts between operations and the policy for the resolution of conflicts.

Citations form the basis for a web of scientific publications. Search engines, embedded hyperlinks and digital libraries all simplify the task of finding publications of interest on the web and navigating to cited publications or web sites. However the actual reading of publications often takes place on paper and frequently on the move. We present a system Print-n-Link that uses technologies for interactive paper to enhance the reading process by enabling users to access digital information and/or searches for cited documents from a printed version of a publication using a digital pen for interaction. A special virtual printer driver automatically generates links from paper to digital services during the printing process based on an analysis of PDF documents. Depending on the user setting and interaction gesture, the system may retrieve metadata about the citation and inform the user through an audio channel or directly display the cited document on the user's screen.

Our demonstration is a paper-based interactive guide for visitors to the world's largest international arts festival that was developed as part of a project investigating new forms of context-aware information delivery and interaction in mobile environments. Information stored in a database is accessed from a set of interactive paper documents, including a printed festival brochure, a city map and a bookmark. Active areas are defined within the documents and selection of these using a special digital pen causes the corresponding query request along with context data to be sent to a festival application database and the response is returned to the visitor in the form of generated speech output. In addition to paper-based information browsing and transactions such as ticket booking, the digital pen can also be applied for data capture of event ratings and handwritten comments on events. The system integrates three main database components - a cross-media information platform, a content management framework for multi-channel context-aware publishing of data and the festival application database.

Paper persists as an important medium for documents and this has motivated the development of new technologies for interactive paper that enable actions on paper to be linked to digital actions. A major issue that remains is how to integrate these technologies into the document life cycle and, specifically, how to facilitate the authoring of links between printed documents and digital documents and services. We describe how we have extended a general web publishing framework to support the production of interactive paper documents, thereby integrating paper as a new web channel in a platform for multi-channel access.

Interaction design is a major issue for mobile information systems in terms of not only the choice of input-output channels and presentation of information, but also the application of context-awareness. To support experimentation with these factors, we have developed a platform that supports the rapid prototyping of multi-channel, multi-modal, context-aware applications. The paper presents the main components of the platform and describes how it was used to develop a tourist information system for an international arts festival where interaction was based on a combination of speech input-output and interactive paper.

Often collaborative graphical systems lag behind well accepted single-user applications in terms of features supported. The frequently used operations of group/ungroup offered by almost every single-user graphical editor have not been considered by the collaborative graphical editing systems that try to preserve the intentions of the users involved in the concurrent editing. In this paper we present a novel algorithm based on operation serialisation for consistency maintenance in collaborative graphical editing dealing not only with simple operations such as create, delete, move, change colour or position, but also with group/ungroup operations. Based on the classification of conflicts into real and resolvable, an undo/redo mechanism is used in order to re-execute the operations in an imposed serialisation order.

Despite the wide-ranging recognition that paper remains a pervasive resource for human conduct and collaboration, there has been uncertain progress in developing technologies to bridge the paper-digital divide. In this essay we discuss the design of a technology that interweaves developments in new materials, electronics and software, and seeks to provide a cheap and accessible solution to creating new affinities between digital content, in whatever form, and ordinary paper. The technology and its design draws from a broad range of field studies, including research in classrooms and museums. These delineate the requirements and considerations that inform solutions to enhancing paper whilst preserving its integrity. The paper also discusses a naturalistic experiment, an evaluation in a museum, where we assessed the technology and the solution. We also chart the progressive development of this solution and the ways in which seemingly simple actions and issues became reconstituted as highly complex technical and analytic problems.

We present a general model and information server for the digital annotation of printed documents. The resulting annotation framework supports both informal and structured annotations as well as context-dependent services. A demonstrator application for mammography that features both enhanced writing and reading activities is described.

We present a general Web-based information infrastructure capable of supporting the rapid development of highly-interactive information environments that cater for widely varying requirements across application domains and all forms of fixed and mobile client devices. In particular, we describe how this infrastructure has been extended to support digitally augmented paper through a special transformation component that can map active areas of document pages to information objects so that user and context-dependent interaction can be supported. Our infrastructure is sufficiently general and flexible to adapt to, not only emerging and even unanticipated technologies in the area of interactive paper, but also the rapidly expanding interaction sphere of hypermedia.

The authors present a general model of database connectivity for the controlled sharing and migration of information across databases as supported in the object-oriented database management system OMS Connect. A database may connect to one or more other databases, thereby enabling remote data to be viewed, processed and copied within the local database in such a way that consistency of the user working space can be maintained. Further the objects of the remote database may be extended locally with attributes and methods and additional classifications. Importantly, operation of the local database is not dependent on such a connection and remote objects may be replicated locally with explicit synchronisation points, thus making the system suitable for mobile computing.

In the last few decades, the execution of various scientific experiments aimed at a more comprehensive understanding of one's environment, has shown a tremendous increase in data production. Database models provide a more or less adequate mechanism for mapping real-world applications into a computer-bound reality. Since scientific knowledge can be modelled a priori only to some extent, the question arises of how able a database schema is to evolve. On the other hand, knowledge can be provided by the underlying scientific data on which data mining algorithms are applied. The main question which arises is how to provide a suitable environment in order to accommodate the results coming out from data analysis tasks and how these tasks can be supported by a database model.

In response to pressures to reduce product lead times, manufacturing companies are increasingly aware of the need for some form of integration along the whole product chain. Engineering tasks must be coordinated and data exchanged between the various specialised tools. An enterprise has two main tracks of information flow, namely technical and managerial, and product data management spans both tracks. On the technical track, applications are highly specialised supporting tasks such as product design (CAD) and the programming of numerically controlled machines (CAM). Generally, the various application systems on the technical track are referred to as CAx systems. CAx systems may not only differ in terms of functionality but also in terms of the amount and type of data managed, the run-time environment and performance characteristics.

We describe an approach to the coordination of application systems based on the modelling and maintenance of inter-system dependencies expressed as data constraints together with update propagation rules. These dependencies are specified by a Coordination Model which comprises a Coordination Interface for each application system together with a global Coordination View. A Coordination Interface describes local object types relevant for system-wide coordination. The Coordination View describes the subsystems, their globally important object types and the relationships between those object types. Additionally, the Coordination View specifies actions to restore global consistency in the event of constraint violations, thereby providing system coordination. Specifically, we describe how this approach has been adopted in a prototype Computer Integrated Manufacturing (CIM) system based on the coordination of CIM subsystems. In this CIM system, the Coordination Model is specified using the NIAM data model.