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CHAPTER 8. CONCEPTUAL EVALUATION
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Synchronisation Scope Furthermore, the synchronisation might be component based, i.e. at
the level of the element container; page based, i.e. at the level of the underlying web
page; or element based in case elements are directly connected.
Synchronisation Consistency This aspect defines how complex it is to maintain synchronisation across devices and web sites. In a consistent system, resynchronisation is easy
to achieve; while in a inconsistent system, resynchronisation is hard to achieve. An example of similar observations might be found in Lowet and Goergen [17] (robustness
of JavaScript engine output synchronization).
Type of Components This dimension analyses the type of components used in the distribution. These can be widgets, i.e. small, pre-built, self-contained, web applications; or
web components, intended as parts of web sites.
Components Creation Here, we define the mechanisms that can be supported for creating components. Components might be pre-built, i.e. widgets; scripted at designtime, i.e. by developers working on the cross-device-mashup; or generated by directmanipulation of web pages.
UI Behaviour Depending on the architectural decisions, DOM elements exposed inside the
front-end components might behave as if in a native browser window, or in a less
natural way. The behaviour, therefore, might be defined as expected, or unexpected.
An example of similar observations might be found in Lowet and Goergen [17] (UI
experience).
Robustness to Errors As observed in Highlight [21], re-authoring web page content might
introduce errors occurring inside the components: these problems might affect the entire cross-device mashup (low robustness), or be limited to the particular web page
(high robustness).
Flexibility to Changes This dimension analyses the flexibility to changes, e.g. because of
evolving web sites, in the source of the re-authored pages [1]. It might be high if
components can adapt well to the new source, or low if no adaptation is provided.
Type of Collaboration The infrastructure might support different types of collaboration: colocated, if the users work in geographical proximity; remote, if the users do not work
in proximity; or both.
Scalability This dimension defines whether the cross-device mashup infrastructure is scalable, i.e. both front-end and network traffic support a large number of users; or not
scalable.
8.2
Discussion
Architechture
Jigsaw is based on a client/server remote control architecture, where the whole cross-device
mashup lies on the server. The thin client, therefore, only initiates operations which are then
carried on in the back-end: this is true for structural operations, like moving a component,