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Background documentation UME Cache  Locate the document in its SAP Library structure

When a user logs on to the SAP NetWeaver Application Server (AS) Java, the user management engine (UME) reads the user’s group and role assignments:

        Direct group assignments

      Direct role assignments

      Indirect group assignments

      Indirect role assignments

From this information, the UME creates a list of UME actions and determines the permissions assigned to the user. The UME stores this information in a cache on the node where the user is logged in.

This graphic is explained in the accompanying text

Permissions of a User Stored in the User Cache


Another example of a use of the UME cache is when an administrator looks for all the members of a group, the UME records information about the group and its members in the UME cache on the server.

The UME refreshes this cache whenever you change group or role assignments. By default, the UME refreshes the cache automatically after the user has been logged in for about an hour.

The cache uses the initial cache size to keep the cache current. The initial cache size is configurable. By default the UME is configured to cache the information for up to 5000 objects. In actual operation, the number of objects cached can exceed the configured value temporarily. When the number of objects in the cache exceeds the initial cache size, the cache marks selected objects as candidates for deletion. When the garbage collector runs, it evaluates the entries and removes objects until the cache is down to the required size. Objects remain in the cache until the garbage collector removes them or you restart the server. You can also manually trigger a cache refresh.

More Information:

      Monitoring the Performance of the UME Cache  

      Optimizing Performance With the UME Cache 

      Refreshing the User Caches of the AS Java  

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