Nowadays, plugin-based applications are quite common. Eclipse is probably the most popular example of such an application. By means of plugins, end-users can add or remove functionality even at runtime. Besides the kernel, plugin-based applications can be kept very small and nearly everything can be designed as a plugin. However, if plugins are added at runtime, their ordering is difficult to organize. This can be observed for graphical user interface representations of plugins, such as menu or list items for example. In particular, the kernel may not refer to a single concrete plugin, since it has to be independent of concrete plugins-according to the plugin concept. Therefore, self-organization is proposed in the present paper as a solution to structure plugin-based applications. A pattern for linearly ordered plugins is presented. The end-user still retains the possibility to reorder the plugins manually according to his preferences. A sample application of the presented pattern in the context of graphical user interfaces is described.

Nowadays, Rich Internet Applications (RIAs) gain more and more popularity. They allow to deliver internet applications that offer a user expericence known from desktop applications. Since in traditional browser centric internet applications the server delivers the content that is to be displayed, the applications can flexibly adapt their functionality to the application's state and context (e.g. the permissions granted to the current user) at any time. As for RIAs, things are different. Normally, they exist in a pre-compiled form-for example as a swf-file. Therefore, they don't allow any dynamic customization of their functionality during runtime. However, it would be eligible that components used in a RIA (e.g. navigation structures) are able to adapt automatically-whenever any change in the application's state or context occurs-to that new state or context. Thus, the RIA components could provide a view onto the application that is totally in sync with its current status and context. In this paper, we present a pattern which allows an easy implementation of this behavior. Then we will show a case study where this pattern has been applied successfully.

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