It has become very popular to build web sites that use and embed widgets from various providers. For example, MySpace and Facebook let their users easily embed various JavaScript widgets and Flash-based applications and videos onto their personal pages. In most cases, the widgets act in a standalone fashion, unaware of the other widgets contained on the same page. Standalone widgets are fine for simple portal pages but for more targeted applications some level of interaction among the components on the page is needed. When such interactions are needed, they are usually achieved through tightly-coupled point-to-point integrations between the widgets which can make it difficult to add new widgets or remove widgets from the page. This links show how a publish/subscribe architecture can be used to integrate Flex and Javascript widgets embedded on a page in a loosely-coupled manner:
PageBus
OpenAjax Hub
