Release 10.1A: OpenEdge Development:
Progress Dynamics Advanced Development

> ## Why cache?

> The frequency of data requests and the amount of data sent across the wire impact the performance of distributed and thin network clients. An application’s performance can be drastically improved if frequently accessed data is cached on the client, allowing the application’s data objects to operate on data in the cache rather than relying on repeated server calls. This approach not only reduces network traffic, but it also decreases the demand on the AppServer’s resources and thereby increases the application’s scalability.

> The two most important development issues with caching are:

> - Data in the cache becomes stale as the underlying database data changes.

> - Too much data in the cache might have a negative impact on performance.

> Therefore, caching is most applicable and valuable for data that are frequently used, relatively static, and have low volume. Since there is no generic way to identify data that will most benefit from caching, it is up to you to enable caching for suitable data and thereby improve the overall performance of your application.

> Prior to Progress Dynamics Version 2.1B, the framework supported caching features devoted to managing data navigated by dynamic lookups and dynamic combos. Version 2.1B implements a new type of caching at the SmartDataObject level. Dynamic lookups can continue to use the existing lookup-based caching, and this functionality has been enhanced to provide better performance in Version 2.1B. SDO-based caching does not apply to dynamic lookups. Dynamic combos can continue to use the combo-level caching, or they can use the new SDO-level caching.

> Note: If you have existing custom code that uses the ADM2 APIs for DynCombo and DynLookup, be aware that these APIs have changed. See Documentation Notes for 10.0B Service Pack 2 for a list of the changes. Progress Software Corporation strongly recommends updating your existing code to use the new APIs as quickly as possible. Also, see OpenEdge Development: Progress Dynamics Administration for related performance information.

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