A whole cult seems to have appeared to praise the virtues of Docker.
Now while Docker is useful, us old mainframe hacks get a sense of deja vu.
Firstly we had VM that can act as a host for other VM instances and for MVS (z/OS) and DOS/VSE. So that is just like virtual machines today such as VMWare and Parallels. This is known as full virtualization.
But we also have operating system level virtualization, or containers. Here the cult around Docker is suggesting that this is the best innovation in IT for decades. Well that’s interestingly almost true. Because the principles underlying Docker have been around for decades. In IBM mainframe terminology they are MVS address spaces.
So what does a container do? – it allows multiple applications to run under the control of a single operating system, yet remain securely separate from each other.
What does an MVS address space do? – it allows multiple applications to run under the control of a single operating system, yet remain securely separate from each other.
Notice any similarities here?
Now I am not suggesting that people cut off their noses to spite their faces. Docker is certainly a very useful technology and its use is spreading widely. I just suggest that people realize that this is no new, brilliant idea.