ex11 + ssh X11 forwarding

Joe Armstrong <>
Fri May 7 23:55:20 CEST 2004


(Hi Hal)

Let me try and give a quick answer here.

The ex11 initialization is a total pain in what I believe
you Americans call the butt - just when I think it works on 
all know machines - it fails. This is (I think) because many machines 
are mis configured but miraculously the standard X libraries account
for all the different forms of mis-configuration.

Just when I thought things were working ex11 bombed on a machine
that returned a fully qualified hostname
whereas the machine where I had tested return just the first part of the 
hostname....

The X forwarding through SSL works fine on my test machine (home + work)
but is also know to fail.

On some systems UNIX domain sockets work on other they don't

On some machine ... etc.

All this has been seriously delaying the next release 
(This is a shame since I've implemented a emacs-widget,
a canvas widget, list selector widget, map widget ....etc.)
((Oh and even erlpoint - my humble attempt at a power point clone))

What I will do is the following:

I'll re-write the initialization to produce a nice 
error report in a file and ask people to send it to me if
initialization fails.

If you guys (and this is mean in the American sence of the word
and is not intended as a gender specific reference) can run 
this on as many machines as possible I should be
able to figure out some code that works on all machine no matter how 
screwed up their configuration files are.

Some other stuff that I just got working is my "polyport" server
- a polyport is a port which understands a heck of a lot of different 
protocols. This means you can send Erlang terms/Erlang binaries/XML 
terms/and HTTP request all to the same port and the polyport figures out 
which middle man to call and bob's your uncle .. Utopian bliss.

I have a polyport server running on one of the planet lab nodes -
unfortunately it dies when I log out - even though I've nohup'ed it.

My goal is to implement a P2P IRC/distributed file systems on
planet lab and interface it through polyports ((Why? - so people using
"other languages" TM (poor sods) can write their own clients using
(horrors) XML or some other daft stuff.

Programming a polyport server (or client) in Erlang is a doodle, and
the XML is for free as it were. The trick (if it can be called a trick)
is to just to replace the Erlang external term format with  an XML 
representation, then you get an XML interface for free. 

So far my polyport acts as a web server and a factorial machine.

If you send the port {fac, 100} it replies 
93326215443944152681699238856266700490715968264381621468592963895217599993229915
608941463976156518286253697920827223758251185210916864000000000000000000000000.

and if you send it 

<?xml version="1.0"?>
<tuple>
 <atom>fac</atom>
 <int>20</int>
</tuple>

it replies

<int>2432902008176640000</int>

Which appeals to my sense of humor.

	-oOo-

I guess if you've been reading this list you'll now realise why I want to 
start collecting middle men :-)

It also prompts the following question:

How many differnt protocols can we distiguish my parsing the first 
line of the protocol??

So far I can detect the difference between Erlang terms HTTP and XML but I 
guess this breaks down quickly :-(

It's a pity the people who wrote all those RFC's didn't have the benefit 
of hindsight

It is late - and I must go and sleep

Let the force be with you

/Joe


On Fri, 7 May 2004, Hal Snyder wrote:

> Joe Armstrong <> writes:
> 
> > I have totally rewritten the Xauthentication routines :-) and use
> > unix domain sockets now.
> 
> Joe you are a wizard and a rabble rouser what with UBF, ex11, your new
> army of middlemen, and so many other interesting creations.
> 
> 
> I am still plodding along absorbing the ideas from the last couple
> brainstorms. Specifically, the latest ex11 downloaded seems to have
> trouble when going through an ssh-forwarded connection. If I open an
> xterm and ssh to a remote host with X11 forwarding enabled, I can run
> xeyes and emacs-with-X and such, but ex11 is no go until going back to
> manually specified DISPLAY of my workstation and xhost +remote_host
> back on the workstation.
> 
> ssh to remote_host with X11 forwarding enabled gives you DISPLAY in
> the remote session of remote_host:13.0 or such.
> 
> 
> ISTR talk of a fix for this. Is there one, or are there hints where to
> start digging re xauth and such?
> 




More information about the erlang-questions mailing list