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6.2. Hardware Virtualisation
the fact that the usage of CORBA can solve communication problems in a distributed software
architecture with VMs, it also provides additional advantages:
• CORBA is (quite) platform-independent because there exist several implementations for
various object-oriented programming and scripting languages under different operating
systems.
• CORBA is an industrial standard for middle-ware, which supports the processes of
verification and validation.
• CORBA supports in general the usage of distributed systems.
The presented example for open models with hardware virtualisation and CORBA was very
simplified because all software models normally do not consist of only one interface, but it is
for example possible to build a complex model by using several interfaces.
An alternative for the integration of CORBA could be the D-Bus [31] system, which is
quite popular in most Linux [47] distributions. Like CORBA, D-Bus implementations are
available for several different platforms and supports platform crossing communication. It also
uses an object model and differs only slightly in the terminology since the concrete interface
implementations are called adaptors. The main difference, compared to CORBA, is that the
bus, the interconnection between objects and proxies, is the central component. In CORBA,
there exist different possibilities for the proxy to servant connection since always a so-called
Interoperable Object Reference (IOR) [41] of the servant is needed. Only one possible way is
to exchange the IOR via a CORBA name server [41], which is similar to the bus mechanism
of D-Bus. Interfaces are defined for D-Bus as XML, from which a class for the adaptor
implementation and for the proxy is generated [31].
D-Bus mainly provides the same advantages as CORBA besides that it is not that frequently
used in industrial applications but more on Linux (desktop) systems. Especially, when executed
on a Linux system, D-Bus adds the advantage that system wide bus [31] is mostly available
and session related buses can easily be created.
6.2.5. Hardware Device Access
As for the inter-processes communication (Subsection 6.2.4), also the access to certain hardware
components could be solved by the employment of a middle-ware, like CORBA or D-Bus.
Accordingly, a general interface for each hardware component type would have to be defined,
which must be implemented by any hardware supplier. Unfortunately, this platform-specification
adoptions would have be executed directly on the target platform to guarantee access to the
related hardware component, which is in conflict with the idea of using hardware virtualisation.
Hence, the usage of a hypervisor that provides configurable access to certain hardware
components renders the concept of hardware device access through a middle-ware obsolete and
accordingly is preferable.
6.2.6. Hardware Virtualisation on Certified Supplier Hardware
A typical usage case for an open model software is that a supplier uses the open model and
open source elements, adds certain own supplier implementations, and compiles it for a certain
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