Development challenges in web apps for public displays

Digital public displays can have a key role in urban ubiquitous computing infrastructures, but they have not yet managed to fill this role. A key step in that direction would be the emergence of an application model for open display networks that would enable anyone to create applications for display infrastructures. In this work, we study the development of web-based applications for public displays. We report on our experience of application development for real world public deployment and also on an experiment with external web developers to assess their ability to create such applications using our own development tools. The results show that the web-based app model can effectively be used in the context of public displays and that web developers are able to leverage upon their expertise to create this type of applications.(undefined

Application diversity in open display networks

We envision that future public display networks will be more interactive and open to applications from third parties similar to what we already have with smartphones. This paper investigates the application landscape for interactive public displays aiming to understand what would be the design and usage space for this type of applications. In particular, we explore people’s perceptions and expectations regarding the diversity of applications that may emerge in future application ecosystems for public displays. We have devised a research methodology anchored on what is currently the rich and diverse range of applications in the mobile application market. We used a set of 75 mobile applications from Google Play application store and asked 72 participants about their relevance for public displays. The results showed that people had a clear preference for applications that disseminate content, and also that these preferences are affected by the type of location where the displays are deployed. These insights improve the understanding of the variables that may affect diversity in future display application ecosystems and inform the development of potential app stores in this context.Fundação para a Ciência e a Tecnologia (FCT

Evaluation of a programming toolkit for interactive public display applications

Interaction is repeatedly pointed out as a key enabling element towards more engaging and valuable public displays. Still, most digital public displays today do not support any interactive features. We argue that this is mainly due to the lack of efficient and clear abstractions that developers can use to incorporate interactivity into their applications. As a consequence, interaction represents a major overhead for developers, and users are faced with inconsistent interaction models across different displays. This paper describes the results of the evaluation of a widget toolkit for generalized interaction with public displays. Our toolkit was developed for web-based applications and it supports multiple interaction mechanisms, automatically generated graphical interfaces, asynchronous events and concurrent interaction. We have evaluated the toolkit along various dimensions - system performance, API usability, and real-world deployment - and we present and discuss the results in this paper.(undefined

Framework de sincronização para aplicações em ecrãs públicos

Dissertação de mestrado integrado em Engenharia de ComunicaçõesAs redes de ecrãs públicos de grande escala são um paradigma emergente e constituem uma transformação radical na forma como se encara a disseminação de informação em espaços públicos. Apesar de existirem já várias soluções proprietárias para ecrãs públicos, estas acabam por ter uma utilidade limitada devido ao facto de constituírem soluções fechadas. Neste trabalho de mestrado, estudamos os principais requisitos na sincronização de aplicações em ecrãs públicos e apresentamos um Framework, que inclui não só um modelo de sincronização, mas também uma API (Aplication Programming Interface) para programadores de aplicações para ecrãs públicos. Este Framework é baseado no PubSubHubbub, um protocolo de comunicação distribuída para a Internet, baseado no modelo Produtor/Subscritor. Para exemplificar e avaliar a utilidade da Framework proposta foi desenvolvida uma aplicação distribuída que faz uso da mesma, constituindo assim uma prova de conceito do trabalho realizado. A aplicação desenvolvida foi colocada em servidores públicos e partilhada por um conjunto de instalações de redes de ecrãs.Large-scale pervasive public displays networks are becoming an emerging paradigm and represent a radical transformation in the way we think about information dissemination in public spaces. One of the features of pervasive public display systems is their ability to create experiences that span across multiple displays in a coordinated fashion. Proprietary single site display solutions exist but these are not open to third-party developers. On the other hand, scalable open systems that enable large-scale, synchronized and multiscreen experiences, spanning multiple networks domains will call for the definition of multiple administrative boundaries that accommodate function partitioning. In our research, we have studied the key requirements involved in this open application synchronization and present our work on designing a Framework - a synchronization model and Application Programming Interface-for public displays application developers that is built on top of the PubSubHubbub protocol, an open protocol for distributed publish/subscribe communication on the Internet. At the end, we also describe the design and implementation of a proof-of-concept that consists of a pervasive public display system formed by a display application, deployed in independent public servers and shared by a set of public displays installations

Investigating conflicts of interests between stakeholders of public display app stores

Public displays showing static content such as news and advertisement are very common, but are often ignored of users expecting them to show uninteresting content. Although applications showing dynamic content which could reduce the display blindness exist, distribution channels and concepts for successfully moderating user-generated content on public displays are still missing. We developed an app store for public displays and analyzed six potential moderation strategies for, in particular, user-generated content. To do this, we conducted an online survey. Survey participants mostly specified that content moderation is necessary and preferred a reactive moderation strategy. Moreover, they expected their messages to appear instantly. Therefore, we developed the UniDisplay application and did an in-the-wild-deployment to investigate the impacts of moderation delays on user behavior. We conducted data and content analyses, observations, a survey and interviews with users of our application. Hence, we can show that already a short delay time of messages (90 seconds) may confuse users and that the delay time is not the only strong factor for posting to a display. On this basis, we built a theoretical concept for integrating content moderation in public display app stores. In the long term, understanding the impacts of moderation strategies for public displays will help to build trust between different stakeholders such as display owners and users. In addition, it will cause public display content to become more dynamic and therefore more interesting for the users.Displays im öffentlichen Raum, die statischen Inhalt wie z.B. Nachrichten oder Werbung anzeigen, sind weit verbreitet. Sie werden jedoch sehr oft von Benutzern ignoriert, da diese erwarten, dass nur uninteressanter Inhalt angezeigt wird. Obwohl bereits Anwendungen existieren, die dynamischen Inhalt anzeigen und damit die Aufmerksamkeit der Benutzer erhöhen könnten, fehlen Plattformen zur Verteilung der Anwendungen und Konzepte für die erfolgreiche Moderation von dynamischem Inhalt auf öffentlichen Displays. Wir entwickelten einen App Store für öffentliche Displays und analysierten sechs potentielle Moderationsstrategien, insbesondere für nutzergenerierten Inhalt. Wir führten außerdem eine Online-Umfrage durch. Die Teilnehmer gaben mehrheitlich an, dass Inhaltsmoderation notwendig ist und bevorzugten eine reaktive Moderationsstrategie. Außerdem erwarteten sie, dass Nachrichten sofort auf dem Display erscheinen. Des Weiteren entwickelten wir das UniDisplay und führten Daten- und Inhaltsanalysen, Beobachtungen, eine Umfrage und Interviews mit den Benutzern unserer Anwendung durch. Wir zeigen, dass bereits eine kurze Verzögerungszeit der Nachrichten (90 Sekunden) für Verwirrung bei den Benutzern sorgen kann und dass die Verzögerungszeit nicht der einzige Faktor ist, der beim Veröffentlichen einer Nachricht relevant ist. Auf dieser Basis entwickelten wir ein theoretisches Konzept wie Inhaltsmoderation in App Stores für öffentliche Displays integriert werden kann. Auf lange Sicht wird das Verständnis über die Auswirkungen verschiedener Moderationsstrategien auf Displays dazu beitragen, dass das Vertrauen zwischen den verschiedenen Interessengruppen wie Displaybesitzern und Benutzern wächst. Zusätzlich hilft das Verständnis dabei, dass der Inhalt von öffentlichen Displays dynamischer und damit auch interessanter für die Benutzer wird

Understanding and supporting mobile application usage

In recent years mobile phones have evolved significantly. While the very first cellular phones only provided functionality for conducting phone calls, smartphones nowadays provide a rich variety of functionalities. Additional hardware capabilities like new sensors (e.g.~for location) and touch screens as new input devices gave rise to new use cases for mobile phones, such as navigation support, taking pictures or making payments. Mobile phones not only evolved with regard to technology, they also became ubiquitous and pervasive in people\u27s daily lives by becoming capable of supporting them in various tasks. Eventually, the advent of mobile application stores for the distribution of mobile software enabled the end-users themselves to functionally customize their mobile phones for their personal purposes and needs. So far, little is known about how people make use of the large variety of applications that are available. Thus, little support exists for end-users to make effective and efficient use of their smartphones given the huge numbers of applications that are available. This dissertation is motivated by the evolution of mobile phones from mere communication devices to multi-functional tool sets, and the challenges that have arisen as a result. The goal of this thesis is to contribute systems that support the use of mobile applications and to ground these systems\u27 designs in an understanding of user behavior gained through empirical observations. The contribution of this dissertation is twofold: First, this work aims to understand how people make use of, organize, discover and multitask between the various functionalities that are available for their smartphones. Findings are based on observations of user behavior by conducting studies in the wild. Second, this work aims to assist people in leveraging their smartphones and the functionality that is available in a more effective and efficient way. This results in tools and improved user interfaces for end-users. Given that the number of available applications for smartphones is rapidly increasing, it is crucial to understand how people make use of such applications to support smartphone use in everyday life with better designs for smartphone user interfaces.Mobiltelefone haben sich innerhalb der letzten Jahre signifikant weiterentwickelt. Während erste Modelle lediglich Sprachtelefonie zur Verfügung stellten, ermöglichen heutige Smartphones vielseitige Dienste. Technologische Fortschritte, wie beispielsweise GPS-Lokalisierung und berührungsempfindliche Displays, haben neue Einsatzbereiche für Mobiltelefone eröffnet, wie solche als Navigationsgerät oder als Fotoapparat. Doch nicht nur in Bezug auf die Technologie haben sich Mobiltelefone weiterentwickelt, sondern auch in der Verbreitung ist die Anzahl der Geräte enorm gestiegen. Sie werden allgegenwärtig im täglichen Leben genutzt, da sie ihre Anwender bei verschiedensten Aufgaben unterstützen können. Das Aufkommen von Vetriebsplattformen für die Verbreitung mobiler Software erlaubt es dem Anwender selbstständig Modifikationen an der Funktionalität seines Geräts vorzunehmen und dieses an persönliche Zwecke und Ansprüche anzupassen. Bisher ist wenig darüber bekannt, wie sich Anwender die Vielfalt zu Verfügung stehender Applikationen zu Nutze machen. Als Folge daraus gibt es bisher nur rudimentäre Unterstützung für Anwender, die Vielfalt von Applikationen effektiv und effizient einzusetzen. Diese Dissertation ist durch den Wandel des Mobiltelefons vom reinen Kommunikationsgerät hin zum multifunktionalen Werkzeug motiviert. Das Ziel dieser Arbeit ist es, Systeme für die Unterstützung einer besseren mobilen Applikationsnutzung zu entwickeln, deren Design auf dem neuen Verständnis von Benutzerverhalten beruht, das durch empirische Studien gewonnen wird. Diese Dissertation hat einen zweiteiligen Beitrag: Zum einen werden theoretische Erkenntnisse dazu erarbeitet, wie Anwender die Applikationsvielfalt nutzen, installierte Applikationen auf ihren Geräten organisieren, neue Applikationen entdecken und zwischen diesen in der Ausführung wechseln. Die Erkenntnisse hierzu beruhen auf der empirischen Beobachtung von Nutzungsverhalten. Zum anderen hat diese Arbeit ingenieurwissenschaftliche Ziele dahingehend, die Anwender von Applikationen dabei zu unterstützen, ihre Smartphones sowie deren Funktionsvielfalt effektiver und effizienter einzusetzen. Dieser Beitrag resultiert in der Beschreibung implementierter Systeme und verbesserter Benutzerschnittstellen für Anwender. Angesichts der rapide wachsenden Zahl zur Verfügung stehender mobiler Applikationen ist es wichtig, zu verstehen wie Endanwender diese nutzen, denn nur so kann die Nutzung von Smartphones gebrauchstauglicher und einfacher gestaltet werden

Designing application stores for public display networks

Current public display systems are often ignored by passersby. We believe that increasing the level of engagement requires substantial innovation for the content shown -- and that this in turn requires opening up displays to new forms of applications and content from a wide variety of sources. In this paper we consider the design of "application stores" that are intended to facilitate the introduction of these new forms of content in future display networks