An adapter that runs as part of the Event Stream Processor Server is called an internal adapter. An adapter that runs as a separate process is called an external adapter.
Internal adapters are started by the ESP Server when it starts the corresponding project (query module). The adapter is recognized by SAP Sybase Event Stream Processor Studio, and from inside the ESP Studio, you can attach the adapter to a stream by selecting the adapter from a menu of adapters. A disadvantage of internal adapters is that if the adapter fails, it may also cause the Server to fail.
External adapters have more flexibility than internal adapters and can run on a different machine than the Server. They can be either managed or unmanaged. Managed external adapters provide an adapter configuration file (.cnxml) that can be configured using Studio, referenced in a CCL ATTACH ADAPTER statement, and can be started and stopped by the ESP Server, behaving very similarly to an internal adapter. Unmanaged external adapters are not referenced in a CCL ATTACH ADAPTER statement, and are not managed by the Server. You start, stop, and configure these adapters independently.