Release 10.1A: OpenEdge Development:
Progress Dynamics Administration

Cache architecture

As the name implies, this caching mechanism accommodates two distinct types of data:

Class cache — Containing attribute and other information that defines the class hierarchy.
Entity cache — Containing Repository and application database schema information.

Class cache

Class information along with its attributes amounts to an average data size of 10KB per class. The class definition does not change frequently and is needed to render each of the ADM2 objects. The class definition in Progress Dynamics maps to the ADMProps temp-table definition, which is one of the main data structures in the ADM2 architecture.

Caching the class information in separate procedure files and using the local information at run time significantly reduces the amount of data over the network and AppServer requests required to construct the class hierarchy. The server processing time is also greatly reduced, thereby increasing the availability of AppServer agents for other requests.

Entity cache

Dynamic viewers and SDOs are the main consumers of the entity cache, because they rely heavily on the data field information in the Repository. Passing the data field information, such as NAME, DATA-TYPE, FORMAT, LABEL, and COLUMN-LABEL, for each instance of a data field requires expensive server processing (fetching this information from the database frequently) and associated data passed over the network. The data field information cannot be overridden at the instance level, so there is no danger of caching many copies of the same data fields. Therefore, entity information can be easily cached on the client machines to reduce the network data traffic, AppServer requests, and processing time.

The entity information is cached as Progress dump (.d) files containing information from the data field masters.