Static 

Static pages are not customized.

An end-user at this level gets a page listing all items from each category, sub-category, and type.

The news system administrator uses the Administration servlet to generate static XML documents periodically (for example, every hour on the hour).

The application could build such pages on demand, but it's faster to serve up a pregenerated page than to run a query and build the same page for each user who requests it.  

Semi-Dynamic 

Semi-dynamic pages combine pregenerated lists of items.

An end-user chooses one or more categories, and Dynamic News builds a page listing the items from those categories. The news admin uses the Administration servlet periodically to pregenerate the lists of items in each category.

Like static pages, semi-dynamic pages are built from pregenerated documents to improve performance.  

Dynamic 

Dynamic pages are built when end-users request them. Content comes directly from the database; nothing is pregenerated.

First, an end-user invokes a servlet to choose categories, sub-categories, and types. Next, Dynamic News queries the database for items matching that criteria and uses the result set to build an XML document. Then, as with static and semi-dynamic pages, it applies an XSLT transformation to generate HTML.