To support auditing for an OERA-conformant client, you must create an API on the AppServer especially for generating application events on behalf of the client. The granularity of this API from the client perspective is entirely application-dependent. You can provide remote procedure or user-defined function calls, perhaps parameterized, that generate one audit event at a time to reflect client-specific conditions, or you can simply hide AUDIT-CONTROL method calls inside task-oriented application service calls, such as inventory look ups or other application-specific operations.
If you require a fine-grained application event API to audit client-specific conditions, you might also need to examine active audit policies to identify active application events that the API can generate for specific client calls. It all depends on how general your application event API must be to cover the application functionality.