The introduction of the XHTML component set is aimed to make it easy to port existent Web pages to ZUML. The ultima goal is that all valid XHTML pages are valid ZUML pages. All Servlets handling the submitted form work as usual.

Therefore, existent XHTML pages could share the most powerful advantage that ZUML pages have: rich user interfaces. The richness could be achieved in two ways. First, you could embed Java codes to manipulate XHTML components dynamically. Second, you could add off-of-shelf XUL components into existent pages, just like you add XHTML into XUL pages.

Performance Consideration: If a portion of HTML tags are static, it is better to use the Native namespace as described in the Performance Tips chapter.