You must map a user to a role for the Fabric engine.
The Fabric engine sends out a Common Base Event using the common event infrastructure service that is enabled by default in the WebSphere® Process Server. The common event infrastructure service requires every user that generates a Common Base Event to be mapped to at least one role that has permission to fire events, such as the eventCreator role.
You can map specific users or groups, all authenticated users, or everyone to the role in the Fabric administrative console.