# Overview: XML MetaData Cache Control

The XML MetaData Cache Control is used for fast access to a managed set of key-value pairs. The keys are of type string and the value contains XML data. For more information on source that uses the XML MetaData Cache Control, see "Code Samples: Weblogic Integration" in the WebLogic Integration Code Library, available on dev2dev, which is available at the following URL: http://dev2dev.bea.com/code/wli.jsp.

Using the XML MetaData Cache Control in your business process flow you can retrieve XML metadata from the XML MetaData Cache. The WebLogic Integration Administration Console manages the entries in the cache (add, delete, update). Alternatively, a custom application (such as a NetUI application) can be written to manage the cache. For more information, see Sharing Cache Data Within a Cluster.

The XML MetaData Cache Control is intended to be used in a read-mostly environment. The XML MetaData Cache should only be used for configuration metadata. It is used to cache runtime xml data. Updating cache entries is expensive, as all cache entries in a cluster must be updated, where as read operations are always in-memory operations. The size of an XML value in the cache should typically be less than 100k bytes. Larger sizes will work, but with an increasing cost of updates. The XML MetaData Cache is a global, domain-wide cache. Data from the cache is made available on a permanent basis through file-based storage.

The following figure describes the XML MetaData Cache and XML MetaData Cache Control implementation.

Figure : XML MetaData Cache Control Implementation Overview