Re: [9fans] What makes Plan 9 unique?

[Borja Marcos <borjamar@sarenet.es>]

On Thursday 25 October 2001 11:00, you wrote:
> What makes Plan 9 truly unique? What about it makes it better than
> Solaris, or other UNIX systems?

	I don't think Plan 9 can or should be compared to Unix systems. Plan 9 is 
a distributed system, and Unix is not.

	One of the things that impressed me the most the first time I read a 
description (some years ago, long before AT&T decided to sell research 
licenses), was its capability to work in *heterogeneous* networks. It is
perhaps the most significant feature in Plan 9.

	Another distributed operating system, Amoeba, converts a whole network 
into a sort of huge multiprocessor computer (from the user's point of 
view), but it does not take into account the differences between networks, 
so Amoeba may be good for organizations with a high speed local network.

	Plan 9 does not have automatic process migration like Amoeba, but, for 
the designer of a distributed application, Plan 9 offers the ability to 
decide how to use the network depending on the available resources. The 
figure 1 in the original Plan 9 paper shows an example; CPU and file 
servers linked by a high-speed optic network, and remote terminals working 
from a phone line. The speeds can range from a 9600 bps line to a gigabit 
network.

	Plan 9 offers a per-process namespace that can be configured to make the 
network topology completely invisible to the user or the application 
program. Moreover, it has taken the "everything is a file" idea to the 
extreme. The network services, for example, are seen as files. To open a 
connection you only copy one "master" file, and the new file obtained will 
be the new connection.

	Together with this, Plan 9 offers a very clean network filesystem. It can 
export *anything*. One of my favourite examples is a machine "mounting" 
the TCP/IP stack of another through a network, or a process in one machine 
being debugged by a debugger in another. Classic network filesystems don't 
allow this flexibility.

	The window system makes a heavy use of the "everything is a file" notion, 
and it is extremely flexible and simple. It does not have a specialized 
protocol for network operations such as X11. Offering a file interface, it 
uses 9P. In fact, as the screen itself is a file, you can run one window 
system inside a window.

	This is what I liked most about Plan 9. There are obviously more things. 
The user interface is not the typical interface you see in the rest of 
environments, it shows new ideas. 

	I even love the documentation; a set of two books in the old Unix 
fashion. A set of very well written papers describing the different 
components and tools, and the manpages.

	Summarizing, in a time when you don't see anything new from commercial 
operating system vendors, and when everything is either Unix (note that I 
am a heavy FreeBSD user) or (argghhh) Windows, an operating system with a 
truly innovative design is fresh air ;-)




	Borja.