Arjen Markus (7 February 2016) Long-running calculations are sometimes needed to solve a problem. But if you have to wait for a calculation to finish after say a day of computing and then examine the results only to find out that you made a mistake in the input, you wish there was some way of monitoring the results while the calculation is going on. A technique for this is "online visualization": you adapt the program so that it produces graphical output while running. But that is not possible in all environment. Here is one such environment: you start the calculation on a computer that has no graphical facilities. Another problem: the program needs to be adapted and you may not be able to do so - graphical libraries tend to be highly system-dependent and what do you want to visualize in the first place?
The two programs below are a first experiment to deal with both problems: the first reads the output files from the computational program directly (or at least that is the idea, in the code below it simply produces numbers via a simple mathematical formula). It does so upon request from the second program. The second program presents a straightforward GUI and plots the results as it gets them from the first program. The communication between the two is via sockets. So, you can just start the first program on the same computer as the computational program and start the visualization program on another one, close that program if you have seen enough and restart to see how far your computation progressed.
Note 1: the demo is not perfect. Something odd happens when you press the Select button several times. I have not figured out yet why this happens. And the programs are demos ;).
Note 2: as the data come in as they are calculated, there is no way to scale the vertical axis properly. This has to come from the user. Hence the "scale" entry.
The server program - start this first:
# olvserver.tcl --
# Server for the online visualisation
#
# Accept --
# Accept a connection
#
# Arguments:
# socket Socket to accept the connection on
# ip IP address
# args Additional arguments (not used)
#
proc Accept {socket ip args} {
chan configure $socket -block false
fileevent $socket readable [list getCommand $socket]
}
# CloseServer --
# Close down the server
#
# Arguments:
# socket Server socket to close
#
proc CloseServer {socket} {
close $socket
exit
}
# getCommand --
# Read the comand that was sent and act on it
#
# Arguments:
# channe; Channel to read from/write to
#
proc getCommand {channel} {
global line
if { ! [eof $channel] } {
gets $channel line
switch -- [lindex $line 0] {
"GETTIME" {
# Send start and stop time
puts $channel "TIMESTART 0"
puts $channel "TIMESTOP 1000"
flush $channel
}
"GETPARAMETERS" {
# Send the names of the parameters/substances
foreach p {A B C} {
puts $channel [list PARAMETERNAME $p]
}
flush $channel
}
"GETLOCATIONS" {
# Send the names of the parameters/substances
foreach l {loc1 loc2 loc3 loc4} {
puts $channel [list LOCATIONNAME $l]
}
flush $channel
}
"GETVALUE" {
set record [lindex $line 1]
if { $record >= 0 && $record <= 50 } {
set t [expr {20.0 * $record}]
puts $channel "VALUE $t [expr {sin($t/100.0)}]"
} else {
puts $channel "NOVALUE"
}
flush $channel
}
"DONEINITIAL" {
puts $channel "DONEINITIAL"
flush $channel
}
"RETRIEVEVALUES" {
lassign $line keyword substanceIdx locationIdx
}
}
} else {
close $channel
}
}
# main --
# Start the server - for debugging/development purposes:
# make sure that the socket is closed.
#
set port 8081
set socket [socket -server [list Accept] $port]
wm protocol . WM_DELETE_WINDOW [list CloseServer $socket]
pack [label .label -textvariable line -width 80]The client program:
# onlinevis.tcl --
# Online visualisation and inspection for DELWAQ
#
package require Plotchart
# SetupWindow --
# Set up the main window
#
# global variables
#
global substance ;# Chosen substance
global substanceList ;# List of substances to choose from
global location ;# Chosen location
global locationList ;# List of locations to choose from
global scale ;# Scale for the vertical axis
global status ;# Text showing what the program is doing
global plotParameters ;# Dictionary containing plot parameters
#
# Arguments:
# None
#
proc SetupWindow {} {
global substance
global substanceList
global location
global locationList
global status
global scale
#
# Simple menu
#
menu .menu
menu .menu.file -tearoff false
.menu add cascade -label File -menu .menu.file
. configure -menu .menu
.menu.file add command -label Exit -underline 1 -command exit
#
# Dropdown buttons for the substance and the location
#
ttk::label .textSubstance -text "Parameter:"
ttk::label .textLocation -text "Location:"
ttk::label .textScale -text "Scale:"
ttk::combobox .selectSubstance -values $substanceList -textvariable substance
ttk::combobox .selectLocation -values $locationList -textvariable location
ttk::entry .editScale -textvariable scale
ttk::button .getData -text "Select" -command [list getNewData]
#
# Create the canvas window
#
canvas .cnv -width 800 -height 500 -bg white
#
# Status bar for messages
#
ttk::label .status -textvariable status -relief sunken
#
# Put them in the main window
#
grid .textSubstance .selectSubstance .textLocation .selectLocation .textScale .editScale .getData -padx 4 -pady 4 -sticky w
grid .cnv - - - - - - -sticky news
grid .status - - - - - - -sticky news
}
# ConnectHost --
# Connect to the server (list to port 8081)
#
# Arguments:
# host Name of the host
#
proc ConnectHost {host} {
global channel
global status
set channel [socket $host 8081]
#after 10000 [list BreakConnection $channel]
fileevent $channel readable [list getData $channel]
set status "Retrieving parameter and location names ..."
SendInitialCommands $channel
}
# SendInitialCommands --
# Send the initial commands to the server
#
# Arguments:
# channel Channel to the server
#
proc SendInitialCommands {channel} {
global status
global plot
global plotParameters
puts $channel "GETPARAMETERS"
puts $channel "GETLOCATIONS"
puts $channel "GETTIME"
puts $channel "DONEINITIAL"
flush $channel
set status "Ready"
}
# PlotData --
# PLot the data just received
#
# Arguments:
# time Value for x-axis
# value Value for y-axis
#
proc PlotData {time value} {
global plot
global scale
global plotParameters
if { $plot == "" } {
set tstart [dict get $plotParameters timestart]
set tstop [dict get $plotParameters timestop]
set plot [::Plotchart::createXYPlot .cnv [::Plotchart::determineScale $tstart $tstop] \
[::Plotchart::determineScale 0.0 $scale]]
}
$plot plot data $time $value
}
# getData --
# Get data from the server
#
# Arguments:
# channel Channel to the server
#
proc getData {channel} {
global plotParameters
global substanceList
global locationList
global substance
global location
global record
global status
if { ! [eof $channel] } {
gets $channel line
#puts $line
switch -- [lindex $line 0] {
"PARAMETERNAME" {
lappend substanceList [lindex $line 1]
}
"LOCATIONNAME" {
lappend locationList [lindex $line 1]
}
"TIMESTART" {
dict set plotParameters timestart [lindex $line 1]
}
"TIMESTOP" {
dict set plotParameters timestop [lindex $line 1]
}
"VALUE" {
puts $line
PlotData [lindex $line 1] [lindex $line 2]
after 10 [list getNextValue $channel [incr record]]
}
"NOVALUE" {
# We must wait
set status "Waiting ..."
after 100 [list getNextValue $channel $record]
}
"DONEINITIAL" {
.selectSubstance configure -values $substanceList
.selectLocation configure -values $locationList
set substance [lindex $substanceList 0]
set location [lindex $locationList 0]
}
}
} else {
close $channel
}
}
# getNextValue --
# Send the command to retrieve the next value
#
# Arguments:
# channel The channel to the server
# record The index of the record to retrieve
#
proc getNextValue {channel record} {
puts $channel "GETVALUE $record"
flush $channel
}
# getNewData --
# Get the data that are available for the selected substance and location
#
# Arguments:
# None
#
proc getNewData {} {
global status
global channel
global substance
global location
global substanceList
global locationList
global record
global plot
set record 0
set substanceIdx [lsearch $substanceList $substance]
set locationIdx [lsearch $locationList $location]
puts $channel "RETRIEVEVALUES $substanceIdx $locationIdx"
puts $channel "GETVALUE $record"
flush $channel
if { $plot != "" } {
.cnv delete all
$plot deletedata
set plot ""
}
set status "Retrieving data ..."
}
# main --
# Start the program
#
if { [llength $::argv] == 0 } {
tk_messageBox -type ok -message "Usage: onlinevis <name of host>"
exit
}
set plot {}
set plotParameters {}
set substanceList {}
set substance {}
set locationList {}
set location {}
set scale 1.0
set status "Waiting for connection ..."
SetupWindow
ConnectHost [lindex $argv 0]