#!/usr/bin/python -u
## The -u option above turns off block buffering of python output. This assures
## that each error message gets individually printed to the log file.
#
# Module: radmonAgent.py
#
# Description: This module acts as an agent between the radiation monitoring device
# and the Internet web server. The agent periodically sends an http request to the
# radiation monitoring device and processes the response from the device and performs
# a number of operations:
# - conversion of data items
# - update a round robin (rrdtool) database with the radiation data
# - periodically generate graphic charts for display in html documents
# - forward the radiation data to other services
# - write the processed weather data to a JSON file for use by html documents
#
# Copyright 2015 Jeff Owrey
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see http://www.gnu.org/license.
#
# Revision History
# * v20 released 15 Sep 2015 by J L Owrey
#
import urllib2
import time
import calendar
import subprocess
import sys
import os
import json
import multiprocessing
## Define constants
_TMP_DIRECTORY = "/tmp/radmon"
_RRD_FILE = "/home/pi/database/radmonData.rrd" # the file that stores the data
_OUTPUT_DATA_FILE = "/tmp/radmon/radmonData.js"
_WEB_DATA_UPDATE_INTERVAL = 1
_CHART_UPDATE_INTERVAL = 60
_DATABASE_UPDATE_INTERVAL = 30
_HTTP_REQUEST_TIMEOUT = 5 # number seconds to wait for a response to HTTP request
## Define run time options
deviceQueryInterval = 5.0 # period defines how often the RR database gets updated
deviceUrl = "http://{IP address}:{port}/jsdata" # radiation monitor network address
debugOption = False
### PRIVATE METHODS ###
def getTimeStamp():
"""
Sets the error message time stamp to the local system time.
Parameters: none
Returns string containing the time stamp.
"""
return time.strftime( "%Y/%m/%d %T", time.localtime() )
##end def
def sendOffLineStatusMsg():
"""Sets the status of the the upstream device to "offline" and sends
blank data to the downstream clients.
Parameters: none
Returns nothing.
"""
sTmp = "\"time\":\"\",\"CPS\":\"\",\"CPM\":\"\"," \
"\"uSvPerHr\":\"\",\"Mode\":\"\",\"status\":\"offline\""
lsTmp = sTmp.split(',')
writeJSONfile(lsTmp)
return
##end def
### PUBLIC METHODS ###
def getDataString(deviceUrl, HttpRequestTimeout):
"""Send http request to radiation monitoring device. The response
from the device contains the radiation data. The data is formatted
as an html document.
Parameters:
deviceUrl - url of radiation monitoring device
HttpRequesttimeout - how long to wait for device
to respond to http request
Returns a string containing the radiation data, or None if
not successful.
"""
content = ""
try:
conn = urllib2.urlopen(deviceUrl, timeout=HttpRequestTimeout)
except Exception, exError:
# If no response is received from the device, then assume that
# the device is down or unavailable over the network. In
# that case set the status of the device to offline.
print "%s: device offline: %s" % \
(getTimeStamp(), exError)
sendOffLineStatusMsg()
return None
else:
for line in conn:
content += line.strip()
if len(content) == 0:
print "%s: HTTP download failed: null content" % \
(getTimeStamp())
return None
del conn
if debugOption:
print "%s\n" % content # DEBUG
return content
##end def
def parseDataString(sData, lsData, dData):
"""Parse the radiation data JSON string from the radiation
monitoring device into its component parts.
Parameters:
sData - the string containing the data to be parsed
lsData - a list object to contain the parsed data items
dData - a dictionary object to contain the parsed data items
Returns true if successful, false otherwise.
"""
# Clear data array in preparation for loading reformatted data.
while len(lsData) > 0:
elmt = lsData.pop(0)
try:
dTmp = json.loads(sData[1:-1])
sTmp = dTmp['radmon'].encode('ascii', 'ignore')
lsTmp = sTmp.split(',')
lsData.extend(lsTmp)
except Exception, exError:
print "%s parse failed: %s" % (getTimeStamp(), exError)
return False
# Since the device responded, set the status to online.
lsData.insert(-2, "status=online")
# Load the parsed data into a dictionary for easy access.
for item in lsData:
if "=" in item:
dData[item.split('=')[0]] = item.split('=')[1]
if debugOption and 0:
print lsData
print dData
return True
##end def
def convertData(lsData, dData):
"""Convert individual radiation data items as necessary.
Parameters:
lsData - a list object containing the radiation data
dData - a dictionary object containing the radiation data
Returns true if successful, false otherwise.
"""
result = True
try:
# Convert UTC from radiation monitoring device to local time.
ts_utc = time.strptime(dData['UTC'], "%H:%M:%S %m/%d/%Y")
local_sec = calendar.timegm(ts_utc)
dData['UTC'] = local_sec
except:
print "%s invalid time: %s" % (getTimeStamp(), utc)
result = False
# Clear data array in preparation for loading reformatted data.
while len(lsData) > 0:
elmt = lsData.pop(0)
lsData.append("\"UTC\":\"%s\"" % dData['UTC'])
lsData.append("\"CPS\":\"%s\"" % dData['CPS'])
lsData.append("\"CPM\":\"%s\"" % dData['CPM'])
lsData.append("\"uSvPerHr\":\"%s\"" % dData['uSv/hr'])
lsData.append("\"Mode\":\"%s\"" % dData['Mode'].lower())
lsData.append("\"status\":\"%s\"" % dData['status'])
return result
##end def
def writeJSONfile(lsData):
"""Convert individual weather string data items as necessary.
Parameters:
lsData - a list object containing the data to be written
to the JSON file
Returns true if successful, false otherwise.
"""
# Convert the list object to a string.
sTmp = ','.join(lsData)
# Apply JSON formatting to the string and write it to a
# file for use by html documents.
strJSON = "[{%s}]\n" % (sTmp)
try:
fc = open(_OUTPUT_DATA_FILE, "w")
fc.write(strJSON)
fc.close()
except Exception, exError:
print "%s: write to JSON file failed: %s" % \
(getTimeStamp(), exError)
return False
return True
## end def
def updateDatabase(dData):
"""
Updates the rrdtool database by executing an rrdtool system command.
Formats the command using the data extracted from the radiation
monitor response.
Parameters: dData - dictionary object containing data items to be
written to the rr database file
Returns true if successful, false otherwise.
"""
# The RR database stores whole units, so convert uSv to Sv.
Svvalue = float(dData['uSv/hr']) * 1.0E-06 # convert micro-Sieverts to Sieverts
# Create the rrdtool update command.
strCmd = "rrdtool update %s %s:%s:%s" % \
(_RRD_FILE, dData['UTC'], dData['CPM'], Svvalue)
if debugOption:
print "%s\n" % strCmd # DEBUG
# Run the command as a subprocess.
try:
subprocess.check_output(strCmd, shell=True, \
stderr=subprocess.STDOUT)
except subprocess.CalledProcessError, exError:
print "%s: rrdtool update failed: %s" % \
(getTimeStamp(), exError.output)
return False
return True
##end def
def createGraph(fileName, dataItem, gTitle, gStart):
"""Uses rrdtool to create a graph of specified weather data item.
Parameters:
fileName - name of graph image file
dataItem - data item to be graphed
gTitle - a title for the graph
gStart - beginning time of the data to be graphed
Returns true if successful, false otherwise.
"""
gPath = _TMP_DIRECTORY + '/' + fileName + ".png"
# Create the rrdtool graph command.
strFmt = ("rrdtool graph %s -a PNG -s %s -w 600 -h 150 "
## "-l 50 -u 110 -r "
"-v %s -t %s "
"DEF:%s=%s:%s:AVERAGE "
"LINE2:%s\#0400ff:")
strCmd = strFmt % (gPath, gStart, dataItem, gTitle, dataItem, \
_RRD_FILE, dataItem, dataItem)
if debugOption:
print "%s\n" % strCmd # DEBUG
# Run the command as a subprocess.
try:
result = subprocess.check_output(strCmd, stderr=subprocess.STDOUT, \
shell=True)
except subprocess.CalledProcessError, exError:
print "rdtool graph failed: %s" % (exError.output)
return False
if debugOption:
print "rrdtool graph: %s" % result
return True
##end def
def getCLarguments():
"""Get command line arguments. There are three possible arguments
-d turns on debug mode
-t sets the radiation device query interval
-u sets the url of the radiation monitoring device
Returns nothing.
"""
global debugOption, deviceQueryInterval, deviceURL
index = 1
while index < len(sys.argv):
if sys.argv[index] == '-d':
debugOption = True
elif sys.argv[index] == '-t':
try:
deviceQueryInterval = abs(int(sys.argv[index + 1]))
except:
print "invalid polling period"
exit(-1)
index += 1
elif sys.argv[index] == '-u':
deviceURL = sys.argv[index + 1]
index += 1
else:
cmd_name = sys.argv[0].split('/')
print "Usage: %s {-v} {-d}" % cmd_name[-1]
exit(-1)
index += 1
##end def
def generateGraphs():
"""Generate graphs for display in html documents.
Parameters: none
Returns nothing.
"""
createGraph('radGraph1', 'CPM', "'CPM - Last 24 Hours'", 'end-1day')
createGraph('radGraph2', 'SvperHr', "'Sv/Hr - Last 24 Hours'", 'end-1day')
createGraph('radGraph3', 'CPM', "'CPM - Last 4 Weeks'", 'end-4weeks')
createGraph('radGraph4', 'SvperHr', "'Sv/Hr - Last 4 Weeks'", 'end-4weeks')
createGraph('radGraph5', 'CPM', "'CPM - Past Year'", 'end-12months')
createGraph('radGraph6', 'SvperHr', "'Sv/Hr - Past Year'", 'end-12months')
##end def
def main():
"""Handles timing of events and acts as executive routine managing all other
functions.
Parameters: none
Returns nothing.
"""
lastChartUpdateTime = - 1 # last time charts generated
lastDatabaseUpdateTime = -1 # last time the rrdtool database updated
lastWebDataUpdateTime = -1 # last time output JSON file updated
lastDeviceQueryTime = -1 # last time radiation device queried for data
dData = {} # dictionary object for temporary data storage
lsData = [] # list object for temporary data storage
## Get command line arguments.
getCLarguments()
## Create www data folder if it does not already exist.
if not os.path.isdir(_TMP_DIRECTORY):
os.makedirs(_TMP_DIRECTORY)
## Exit with error if cannot find the rrdtool database file.
if not os.path.exists(_RRD_FILE):
print "cannot find rrdtool database file: terminating"
exit(1)
## main loop
while True:
currentTime = time.time()
# At the radiation device query interval request and process
# the data from the device.
if currentTime - lastDeviceQueryTime > deviceQueryInterval:
lastDeviceQueryTime = currentTime
result = True
# Get the data string from the device.
sData = getDataString(deviceUrl, _HTTP_REQUEST_TIMEOUT)
if sData == None:
result = False
# If successful parse the data.
if result:
result = parseDataString(sData, lsData, dData)
# If parsing successful, convert the data.
if result:
result = convertData(lsData, dData)
# At the web update interval, update the JSON file used to pass
# radiation data to html documents.
if currentTime - lastWebDataUpdateTime > _WEB_DATA_UPDATE_INTERVAL:
lastWebDataUpdateTime = currentTime
if result:
lsData[0] = "\"time\":\"%s\"" % getTimeStamp()
writeJSONfile(lsData)
# At the rrdtool database update interval, update the database.
if currentTime - lastDatabaseUpdateTime > _DATABASE_UPDATE_INTERVAL:
if result:
lastDatabaseUpdateTime = currentTime
## Update the round robin database with the parsed data.
result = updateDatabase(dData)
# At the chart generation interval, generate charts.
if currentTime - lastChartUpdateTime > _CHART_UPDATE_INTERVAL:
lastChartUpdateTime = currentTime
p = multiprocessing.Process(target=generateGraphs, args=())
p.start()
# Relinquish processing back to the operating system until
# the next update interval.
elapsedTime = time.time() - currentTime
if debugOption:
print "processing time: %s\n" % elapsedTime
remainingTime = _WEB_DATA_UPDATE_INTERVAL - elapsedTime
if remainingTime > 0:
time.sleep(remainingTime)
## end while
## end def
if __name__ == '__main__':
main()