1.7 Further Reading

---

1.7 Further Reading

Among the many different ways to regard concurrent programs, the idea that an object-oriented concurrent program can be viewed as consisting of active and passive objects is only one. For example, ADA used the idea of a rendezvous to coordinate between tasks (see the Ada 95 Reference Manual [ADA95] and Barnes [BAR96]) and added the concept of protected types ([ADA95]), which is much closer to the concept of active and passive objects and is very similar to some of the methods used in this book, particularly in Chapter 3. Many other suggestions have been made regarding how to handle concurrent programming. A good text that covers many of the historical aspects of concurrent programming is Gehani and McGettrick [GEH88]. Concurrent programming is still a very active area of research. Two texts that give a very good overview of the issues involved are Bacon [BAC98] and Ben-Ari [BEN90]. Some good texts on concurrent programming specifically in Java are Hartley [HAR98] and Lea [LEA00]. Finally, concurrent programming has traditionally been taught as part of a course in operating systems. This is because problems associated with concurrent programming were first encountered and solved in designing and implementing operating systems, and it is still the responsibility of the operating system to provide a virtual concurrent environment to programs running under them. A number of good books on operating systems address the issues of concurrent programming; see, for example, Stallings [STA01].

That a program can be written completely using only active and passive objects was proposed in a doctoral thesis by Hathorn [HAT88] and forms the basis of what has been called a coordination language (see Gelernter and Carriero [GEL92]). Active and passive objects have also been present in a number of design methodologies (specifically, see Booch [BOO91] and Meyer [MEY88]) and eventually were included in UML (see Booch [BOO99]); however, none of these approaches treats passive objects exactly the same or exactly as they are presented here.

---