Integrating concurrent and object-oriented programming has been an active research topic since the late 1980's. There is a 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 class 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 article discusses ways in which protected objects can be made more extensible.

G. Booch (see ibid., vol.SE-12, no.2, p.211-21, Feb. 1986) has analyzed a problem involving the software of a set of free-floating buoys. The correspondence points out that Booch's analysis fails to address one important system issue, namely the fact that the software must support two concurrent activities, and shows that an analysis according to the M.A. Jackson method will reveal this difficulty at an early design stage. On the other hand, the Jackson approach does not deal with some configuration issues, which are handled in Booch's analysis. This shows that one method is sometimes not enough to address all important, systemwide aspects of a problem. Rather than arguing about which one design method is best, the author recommends taking an electric view and using any combination of approaches that yields important results in a given situation.>

The title of this paper (see ibid., vol.15, p.360-2 (1989)) was printed incorrectly. It should have read: the case for the eclectic design of real-time software.>