The configuration of an instance is broken down into three levels:

• 1) Instance level: The basic settings of an instance such as log behavior or default values are processed at this level. More importantly, however, this is where you define Exchange as the server type and the connection to the data source catalog.
• 2) Action tree level: The action tree configurations are evaluated at the level below the instance level. These determine the scope of selection, which is dependent on the settings for the data source catalog. This is also where you configure the basic filter settings, such as entry points.
• (3) Action level: The action level consists of any number of individual actions that are linked hierarchically. These individual actions represent the actual processing steps. The order of actions in a tree determines the course of processing.

While the configuration is loading, the XML fragments are validated based on the underlying XML schema. This applies both to calling the validation function, which is explicitly limited to the syntactic check of fragments and individual plausibility checks, and to starting element processing. If this configuration check fails, the elements cannot be processed.

The following illustrates the loading of the configuration and the general internal service architecture with the generic example "Archive all messages that have ELO in the subject line":