C++ Programming With CORBA
John Wiley and Sons, February 1999
Reviewed Mar 17, 1999
This first three chapters of this book present an overview of CORBA as of today. It contains all the standard introductory material you would expect : definitions, concepts and a quick first application program to build from scratch.
Its real strength is in chapter 4, "ORB Runtime System". This chapter discusses briefly the BOA (Basic Object Adapter) and then proceeds with its newer and revised version, the POA (Portable Object Adapter). To give some background : the BOA was the first step of the specification but it failed to define a lot of implementation details, like multi-threading policies, activation of objects and servants, security, lifecycle, etc... Thus, all the ORB manufacturers had to supply proprietary implementations.
The OMG acknowledged this omission and fixed it with the POA, which obsoletes the BOA. There is now a standard way to define these parameters thanks to Policies. With Policies, you can specify :
This is a huge progress over the BOA, even though some of these policies could still be more detailed (I find the Threading Policy rather crude and I still miss the flexibility offered by Orbix in that respect). The expertise of the authors really shows in this long chapter, as they regularly make comparisons between the BOA and the POA, showing the problems and how they were addressed.
The chapter 5 discusses how services are discovered and the last two chapters dive into a more detailed example, including advanced functionalities (the Interface Repository and the Dynamic Invocation Interface).
Overall a very enjoyable read although I have to mention a few griefs :
I definitely recommend this book for anyone willing to get acquainted with the POA. In a very reasonable number of pages (330), you will gain a very good insight on what CORBA looks like today and, more importantly, why the Architecture evolved the way it did.
Developers in need of a complete description of CORBA should also read Steve Vinoski and Michi Henning's book, which is considerably more detailed.
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