A. Harth and N. Koch (Eds.): ICWE 2011 Workshops, LNCS 7059, pp. 49–61, 2011. © Springer-Verlag Berlin Heidelberg 2011 Orchestrated User Interface Mashups Using W3C Widgets Scott Wilson 1 , Florian Daniel 2 , Uwe Jugel 3 , and Stefano Soi 2 1 University of Bolton, United Kingdom scott.bradley.wilson@gmail.com 2 University of Trento, Povo (TN), Italy {daniel,soi}@disi.unitn.it 3 SAP AG, SAP Research Dresden, Germany uwe.jugel@sap.com Abstract. One of the key innovations introduced by web mashups into the integration landscape (basically focusing on data and application integration) is integration at the UI layer. Yet, despite several years of mashup research, no commonly agreed on component technology for UIs has emerged so far. We be- lieve W3C’s widgets are a good starting point for componentizing UIs and a good candidate for reaching such an agreement. Recognizing, however, their shortcomings in terms of inter-widget communication – a crucial ingredient in the development of interactive mashups – in this paper we (i) first discuss the nature of UI mashups and then (ii) propose an extension of the widget model that aims at supporting a variety of inter-widget communication patterns. Keywords: UI Mashups, W3C widgets, Inter-widget communication. 1 Introduction If we analyze the state of the art in mashups today, we recognize that basically two different approaches have reached the necessary critical mass to survive: data ma- shups and UI (user interface) mashups. Data mashups particularly focus on the inte- gration and processing of data sources from the Web, e.g., in the form of RSS or Atom feeds, XML files, or other simple data formats; mashup platforms like Yahoo! Pipes (http://pipes.yahoo.com/pipes/), JackBe Presto (http://www.jackbe.com/), or IBM’s Damia [1] are examples of online tools that aim at facilitating data mashup development. UI mashups, instead, rather focus on the integration of pieces of user interfaces sourced from the Web, e.g., in the form of Ajax APIs or HTML markup scrapped from other web sites; Intel Mash Maker [2] or mashArt [3] both support the integration of UI components, but most of the times these mashups are still coded by hand (e.g., essentially all of the mashups on programmableweb.com are of this type). The mashup platforms focusing on data mashups typically come with very similar features in terms of supported data sources, operators, filters, and the like. RSS, Atom, or CSV are well-known and commonly accepted data formats, and there are not many different ways to process them. Unfortunately, this is not what happens in