Towards Awareness and Control in Choreographed User Interface Mashups
Mashups utilizing publish-subscribe-based inter-widget communication approach do not require users to establish connections between widgets explicitly. Communication, i. e. data and control flows emerge as soon as widgets are put together in a workspace (so called choreographed user interface mashups, cf. ). Technically, this is achieved by employing the event-driven approach via publish-subscribe messaging pattern (pub/sub): widgets autonomously subscribe and publish messages on different communication channels, so-called topics. A message bus running within a browser takes care of delivering messages to all interested parties, i. e., widgets subscribed to the corresponding topics.
This, however, implies a lack of awareness and control by end users - an implication which was confirmed in the interviews and observations during the user studies . A profound analysis of the described problems, analysis of possible solutions from related research fields and implications for the PubSub-based systems can be found in the corresponding paper .
The presented approach developed in the course of the OMELETTE project makes use of several extensions to the choreographed mashup composition model. For example, users are able to restrict communication between widgets using so called restrictions, i.e. block one-to-one or one-to-many connections between widgets. Available communication channels and publication-restrictions can be visualized by the platform in order to inform the user about which widgets exchange which data.
 Scott Wilson, Florian Daniel, Uwe Jugel and Stefano Soi. Orchestrated User Interface Mashups Using W3C Widgets. ICWE 2011 Workshops, June 2011, Springer, Pages 49–61.
 Olexiy Chudnovskyy, Stefan Pietschmann, Matthias Niederhausen, Vadim Chepegin, David Griffiths, Martin Gaedke. Awareness and Control for Inter-Widget Communication: Challenges and Solutions (Conference Paper) Proceedings of 13th International Conference on Web Engineering (ICWE2013). Aalborg, Denmark. July 08-12, 2013