Declarative page

A declarative page is a clipboard page created by execution of a declare pages rule (Rule-Declare-Pages rule type).

The name of a declarative page starts with the prefix Declare_. Such pages are created and updated only through operations identified in a Declare Pages rule. The contents of these pages are visible but read-only to requestors.

Benefits

Declarative pages can improve performance and reduce memory requirements when all or many requestors in an application need to access static information or slowly changing information.

For example, a declarative page may hold last night's closing U.S. stock prices in a Value Group property indexed by ticker symbol, so that the property reference Declare_Stock.Price("IBM") is the closing price for IBM shared. The first time each evening (after the 4:30 P.M. New York market close) that a requestor attempts to access the page, the system automatically loads the page with the latest end-of-day prices. The page can remain unmodified in memory until the next day's closing.

In other situations, data values are not static but may change infrequently; the system automatically checks the declarative page contents (using a when condition rule) before each property access to see whether a fresh recomputation is needed. For example, a page may list the part numbers or SKU numbers of items that are out-of-stock, extracted from an inventory control system. Recomputation is needed only as often as an out-of-stock condition begins or ends, not each time the inventory changes.

Notes

Declarative pages are not created at system startup; they are created only when first accessed.

Ordinarily, declarative pages do not persist; they are not saved to the PegaRULES database but are reconstructed when next accessed and the previous version is expired.

On the Clipboard tool display, declarative pages appear as a group named Declared Pages.

On the Performance tool full details display, you can review (for your own requestor session) elapsed time and CPU time statistics associated with creating, finding, and accessing declarative pages, and counts of the number of node-level declarative pages your requestor has accessed.

The system maintains node-level declarative pages in a cache.

	expired page, node, page
	About Declare Pages rules Understanding page names and reserved pages Understanding caching About the Performance tool
	Atlas — Standard Declare Pages rules

Definitions — D