Customizing Content with XML: Dynamic News Application, 4 of 16

Overview of the Dynamic News Application

Dynamic News pulls news items (headlines) from the database to build HTML pages. The HTML pages are customized according to user preferences.

The pages present lists of items, with each item hyperlinked to a complete article. Each news item has attributes including:

Category, such as Sports or Technology
Subcategory, such as Baseball or Software
Type, such as Feature or Review.

Three Levels of Customization: Static, Semi-Dynamic, and Dynamic

Dynamic News uses these attributes to offer three levels of customization:

Static
Semi-dynamic
Dynamic

Table 6-1 describes these usage choices.

Table 6-1 Dynamic News: Three Levels of Customization

Customization Level	Description
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.

Customization Level

Description

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.

Note:
The term "dynamic" and "static" refer to the page contents not its behavior.