How do I add new components to an existing page dynamically?

The short answer here is: you don't. The long answer here is you don't have to, to get the behavior you desire.

One of Tapestry basic values is high scalability: this is expressed in a number of ways, reflecting scalability concerns within a single server, and within a cluster of servers.

Although you code Tapestry pages and components as if they were ordinary POJOs ¹ , as deployed by Tapestry they are closer to a traditional servlet: a single instance of each page services requests from multiple threads. Behind the scenes, Tapestry transforms you code, rewriting it on the fly.

What this means is that any incoming request must be handled by a single page instance. Therefore, Tapestry enforces the concept of static structure, dynamic behavior.

Tapestry provides quite a number of ways to vary what content is rendered, well beyond simple conditionals and loops. It is possible to "drag in" components from other pages when rendering a page (other FAQs will expand on this concept). The point is, that although a Tapestry page's structure is very rigid, the order in which the components of the page render does not have to be top to bottom.