Configurations which are used to control the runtime--as opposed to creation-time--behavior of objects often maintain a set of callbacks for which you can register. They are useful for getting access to internal system events such as the exporting of an object or the sending of a request.

SST supports a wide range of callbacks all of which are listed in the SstConstants pool dictionary. The methods which fire the callbacks detail when they are fired and the call data supplied with each firing. You can register for callbacks using the standard addCallback* protocol which is part of standard Smalltalk.