Integrating Object-Oriented Programming and Protected Objects in Ada 95

Integrating concurrent and object-oriented programming as been an active research topic since the late 1980s. There is now a plethora of methods for achieving this integration. The majority of approaches have taken a sequential object-oriented language and made it concurrent. A few approaches have taken a concurrent language and made it object-oriented. The most important of this latter case is the Ada 95 language which is an extension to the object-based concurrent programming language Ada 83. Arguably, Ada 95 does not fully integrate its models of concurrency and object-oriented programming. For example. neither tasks nor protected objects are extensible. This paper discusses ways in which protected objects can be made more extensible.