MCOP is the standard aRts uses for:
communication between objects
describing object interfaces
One major aspect of MCOP is the interface description language, IDL, in which many of the aRts interfaces and APIs are defined in a language independand way. To use IDL interfaces from C++, is compiled by the IDL compiler into C++ code. When you implement an interface, you derive from the skeleton class the IDL compiler has generated. When you use an interface, you do so using a wrapper. This way, MCOP can use a protocol if the object you are talking to is not local - you get network transparency.
This chapter is supposed to describe the basic features of the object model that results from the use of MCOP, the protocol, how do use MCOP in C++ (language binding), and so on.