This invention relates to the field of interfaces between systems having data needs such as databases and input devices. Specific examples include SAP systems and bar-code readers. In general, these systems are referred to as "external systems." A need exists for a method and system for providing an interface between external systems, such that the user of the external systems can configure an interface based solely on knowledge of the data in the external systems, without a need to have an in-depth understanding of the database model and communication protocols of each of the external systems. Therefore, according to one aspect of the invention, in an interface for communication with a first external system and a second external system, a method is provided for responding to an event, the event being related to communication with at least one of the first or the second external systems, the method comprising: receiving a message, the message comprising a metadata event key and a session identifier, the session identifier identifying a workset database for use with the message, the workset database having a workset database structure upon metadata; and processing an action series dependent upon the metadata event key, wherein said processing is assigned to the session.