VMD-L Mailing List

From: Oliver Beckstein (oliver_at_biop.ox.ac.uk)
Date: Wed Feb 12 2003 - 16:10:04 CST

Hello,

I am looking for help with a tcl script (based on vmdcollab) that
turns vmd into a remote-controlled display server. remote_ctl.tcl is
appended at the end. (I am sorry if this is too much clutter for the
list).

At the moment connecting works (telnet localhost 5555) and so does
sending commands (eg 'draw sphere {1 0 0} radius .3 resolution
24'). My main problem is that I don't know how to tell tcl that I want
VMD's stdout redirected to the socket so that my remote application
(telnet in this case) can read it. I have tried a fileevent handler on
stdout but this did not work (it is called perpetually and I still
cannot access the actual VMD output).

A minor problem is that a wrong command seems to block the connection,
that is, no commands after the first wrong one will have any effect.

And (as is probably obvious from the code): I am a complete newbie at
tcl so any help or comments are very much appreciated.

Thanks,
Oliver

#------------------------------------------------------------------
# $Id: remote_ctl.tcl,v 1.6 2003/02/12 21:33:11 oliver Exp $
# based on bounce.tcl and vmdcollab.tcl
# from http://www.ks.uiuc.edu/Research/vmd/script_library/scripts/vmdcollab/
#
# start this in VMD and send commands to the listening port to have VMD
# execute them remotely
# (also see http://www.tcl.tk/scripting/netserver.html)
#
# Usage: vmd -e remote_ctl.tcl
# or vmd> source remote_ctl.tcl
#
# Security: we only allow connections from localhost (see acpt)
#
# Bugs:
# * once a wrong command was sent, the connection appears
# to 'block' and does not accept correct commands later
# * does not write result back to socket (one way connection...) so
# there is no way to inquire objects in vmd
  
namespace eval remote_ctl {
  variable main
  variable clients
  variable default_vmd_port

  set default_vmd_port 5555

  # I am too dumb to set the default value for port from
  # $default_vmd_port so I put 5555 in there literally
  proc start { {port 5555} } {
    variable main
    set main [socket -server remote_ctl::acpt $port]
    putlog "Listening on port $port"
  }

  proc acpt { sock addr port } {
    variable clients
    if {[string compare $addr "127.0.0.1"] != 0} {
          putlog "Unauthorized connection attempt from $addr port $port"
          close $sock
          return
    }
    putlog "Accept $sock from $addr port $port"
    set clients($sock) 1
    fconfigure $sock -buffering line
    fileevent $sock readable [list remote_ctl::recv $sock]
  }

  proc recv { sock } {
    variable main
    variable clients
    if { [eof $sock] || [catch {gets $sock line}]} {
      # end of file or abnormal connection drop:
      # shut down this connection
      close $sock
      putlog "Closing $sock"
      unset clients($sock)
    } else {
      if {[string compare $line "quit"] == 0} {
        # prevent new connections
        # existing connections stay open
        # No -- Bug(?): 'quit' closes VMD...
        putlog "Disallowing incoming connections by request of $sock"
        close $main
      }
      # execute the received commands
      # should check for runtime errors which otherwise leave the connection
      # in an unusable state
      eval $line
    }
  }

###### would like the last line from stdout in line ###########
# (or any working solution....)
  proc send { sock line} {
    variable clients
    # send reply to connecting client
    putlog "send '$line' to $sock"
    puts $sock $line
  }

 
  proc putlog { text } {
    puts $text
    return
  }
}

# assuming that loading this file means that we actually want to run
# the server, we just start it:
remote_ctl::putlog "Starting remote_ctl server in vmd: connect with something like"
remote_ctl::putlog "telnet localhost 5555"

remote_ctl::start

#------------------------------------------------------------- 

-- 
Oliver Beckstein * oliver_at_bioch.ox.ac.uk
 http://indigo1.biop.ox.ac.uk/oliver/