Object oriented data concepts for SDL

With the 1992 revision of SDL [1], object oriented structuring concepts were introduced into the language. However, some object oriented concepts known from modern languages are still missing, e.g. exception handling and references, which are related to polymorphism as well as late binding of operators. The main reason for these lacks is the formal base of data types ACT ONE [2]. This algebraic calculus makes it more difficult to introduce those concepts. Today‘s applications of SDL are embedded in system designs together with other specification techniques, e.g. IDL [10]. The interaction with these additional techniques requires the extension of SDL with modern language concepts. Humboldt University developed solutions which are implemented in the SDL Integrated Tool Environment (SITE). These solutions are being presented to the ITU-T for standardization in the next revision of SDL.