Overview

The Object Request Broker (ORB) is the key component of the CORBA architecture. Its key responsibility is to forward method invocations from a client to an object implementation, including the tasks associated with this process in heterogeneous environments. In particular, invoked objects may be located in the same process as the caller, in a different process on the same computer, or on a remote computer. Also, objects can be implemented using different programming languages, running on different operating systems and hardware, and connected by diverse types of networks. The ORB has to provide a consistent interface to invoke these different types of objects.

Expandability Because the ORB is closely linked with the other components of a CORBA system (partially through proprietary interfaces), the developers of specialized ORBs were forced to develop new versions of these components of the CORBA system or not to provide them at all. This happens with some research projects in the integration of Quality of Service (QoS) aspects into CORBA ([25] and [32]).

Microkernel architecture So this is the starting point for Mico as a platform for research and training projects: the development of an extendible and modifiable ORB. The microkernel approach from the area of operating systems has been applied to CORBA for this purpose. For this, the minimal necessary ORB functionality has to be identified, such that modifications and extensions can be implemented outside the ORB as services.

Consequently, the following sections start by compiling the tasks of an...