Research And Implementation Of Plug-in For Additional Functions On Widget Platform

Widgets, the applications for some specific functions on various terminals, are very popular in the recent years. JavaScript is widely used to provide behaviors for the common widgets. JavaScript APIs used in those widgets are offered by widget engines but the specifications of APIs are various on the different engines. Therefore, widgets using these platform-specific APIs are not universal. Though some organizations hope to change this status by establishing uniform standard for APIs, the functions that widget could offer, especially those system-related ones, are limited when obeying the standard. Thus, the market-leading widget platforms reserve their special JavaScript APIs or the extension mechanism for JavaScript APIs. However, these platform-specific parts are still the bottle-neck while porting widgets to the different widget platforms.To expose local functions to resolve the portable problem for widgets, a general mechanism should be provided on widget platforms. It allows widget author to add JavaScript API used to offer system-related functions and makes sure that new JavaScript API is cross-platform. From the aspect of appending function to application, adding plug-in is the commonest way. Thereby, the thesis undertakes a study on two aspects. One of them is the current platform-specific extension mechanism for JavaScript API. And the other is the plug-ins supported by widget platforms now. On the current extension mechanism for JavaScript API, the building of extension part and its reference entry are investigated mainly. On the plug-ins supported by widget platform, the principle, usage, loading method, cross-platform ability and scripting ability are investigated.On the base of the above investigations, the thesis summarizes the current extension mechanism of JavaScript API. And according to the common commands for the components of extension mechanism, the thesis searches the point, which could be utilized and extended, in the existing technology framework on widget platforms. By extending the usage of the embedded object in HTML and expanding MIME type, a common extension mechanism is established. It utilizes the embedded object as the entry for JavaScript API extension and Netscape-style plug-in provided the specific extended functions. Further, a new portable developing and working mode for widget, "Widget+Netscape-style Plug-in+Widget engine", is formed. And an implementation on Windows of this mode is offered in the thesis. The widget adopting the implementation has been released and it works well in practice.