Identifying Objects (SAP Library - Architecture of the SAP NetWeaver Application Server)

Identifying Objects

The following identify an object that is intended to be stored, manipulated, or invalidated in the cache:

The fully specified Cache Key, which consists of the URL and the various context-dependent fields, such as SAP language and SAP theme

Example

/sap/bc/bsp/sap/public/bc/bsp/styles/sapbsp.css&de&&A6E90000&

Caution

Although the application can identify objects using the cache key, this is not recommended. Use the following methods that are described using the URL prefix or e-tag.

A wildcard pattern <prefix>*, which selects all objects with a matching <prefix>

Example

/sap/bc/bsp/sap/public/bc/bsp/styles/*

The E-tag, that is, a unique key (GUID) that is assigned to an object when that object is created To create a unique GUID for your object, you can use the ABAP function module GUID_CREATE.

This graphic is explained in the accompanying text

The e-tag is required so that logically identical objects that are physically stored a number of times under different URLs (but with the same e-tags) can be identified. When the object is being invalidated, then, the application uses the e-tag to access all copies of the object simultaneously.

Caution

The e-tag is not automatically assigned to every object by the system (such as the cache key), but is a GUID that the application programmer can assign if he or she wants to access this object at a later date (to invalidate it, for instance).