[9fans] New wiki pages about 9p services and building grids

[mycroftiv 9gridchan]

Hello 9fans! After a year away from public Plan 9 projects and
development I have returned to full-time work on Plan 9 software and
services. Before posting about my current software project, I would
like to make note of two pages I added to the Bell Labs plan 9 wiki
which are intended as an overview of topics in multi-machine Plan 9
setups.

http://www.plan9.bell-labs.com/wiki/plan9/9p_services_using_srv,_listen,_exportfs,_import/index.html

http://www.plan9.bell-labs.com/wiki/plan9/Expanding_your_Grid/index.html

These pages attempt to summarize key concepts in Plan 9, how 9p is
used on a grid of machines and how proceed as you add more machines to
a grid and configure systems for particular roles. I have done my best
to make these pages clear and correct without excessive detail, but it
would be great if some other users with practical experience with
mid-sized and larger grids helped error check and add anything crucial
I omitted.

I also have spent quite a few hours recently trying to add helpful
information to other wiki pages and restructure the organization of
the Documentation page. I have not removed any information or links
although I did rearrange ordering and change the wording of a few
descriptions. If you are a wiki contributor or editor I hope my
changes are for the better and please help improve my edits if I got
anything wrong. :)

I will be posting soon about my current software project for Plan 9
from Bell Labs, which is ready for release, but I would like some more
user testing and feedback before posting an announcement to this list.
If you aren't afraid of Giant ANTS feel free to email me at this
address or look me up in #plan9 irc on freenode.net if you are willing
to help test my software or even just read my documentation and paper
and discuss concepts.

-Ben Kidwell
"mycroftiv"

[Richard Miller]

Thanks for producing this compendium of useful information.

One question - there's a mention of "hubfs", which I wasn't familiar
with until I tracked it down in your contrib area. Perhaps you could
provide a reference?

[m***@sphericalharmony.com]

Date: Sat, 2 Mar 2013 15:32:27 +0000
Thanks for producing this compendium of useful information.
One question - there's a mention of "hubfs", which I wasn't familiar
with until I tracked it down in your contrib area. Perhaps you could
provide a reference?

Thanks for the feedback on the wiki pages and the suggestion. I
created and linked a new wiki page with extensive hubfs documentation
and usage examples.

http://www.plan9.bell-labs.com/wiki/plan9/hubfs/index.html

I wrote hubfs several years ago after noticing the absence of a
general purpose "screen" type utility in Plan 9. aux/consolefs is
focused on a particular use case, serial consoles. I feel that the
excellent Plan 9 design (no tty and 9p to handle local/remote clients
identically) helped me luckily stumble into a very nice simple fs
design that does both "screen" and general purpose network pipe
muxing.

On my current grid, my main cpu server hosts hubfs and every other
machine connects to it and shares services into it, and accesses other
machines through it. I have persistent shells from several Plan 9
systems and two linux systems always available, and a separate hubfs
is used for things like irc sessions and mail reading sessions and
telnet connections to BBSes. My profile does import -a of the /srv of
the main cpu so i can type "hub main lapsh" on any node and then be
connected to the subshell with p9p rc running on my linux laptop which
has a 9p connect to the hubfs server.

I think hubfs is a nice design for bringing shells of machines on the
network into the 9p file namespace. I don't take any personal credit
for any nice things about it, I just tried to find the simplest way to
make a "screen" for Plan 9 and modifying a ramfs to have pipe-like
semantics and a queue of client responses seemed like the simplest way
to do it. As it happened, the simplicity of doing it that way made it
more general purpose than a TTY-based screen and let me separate the
management of the shells from the basic idea of pipe buffering/muxing.

I'm less experienced as a developer than many so there are probably a
few naive things and eccentricities in hubfs, but it has been very
useful to me and in my use and testing it is stable and resource
efficient since all it does is just copy bytes into static buffers and
fill the 9p requests that come in. To me, the fact that getting rid
of the TTY layer means that "screen/tmux" functions can be done in a
vastly simpler way - with new functionality as a free bonus - is a
nice demonstration of the benefits of clean design.

Sorry if this response was unnecessarily long, but thanks for your
interest in the wiki pages and the suggestion to write up and link
hubfs for clarity.

-Ben Kidwell
"mycroftiv"