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server.js
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server.js
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// NightScout server file
// NightScout 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.
// NightScout 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 NightScout.
// If not, see <http://www.gnu.org/licenses/>.
// Description: Basic web server to display data from Dexcom G4. Requires a database that contains
// the Dexcom SGV data.
////////////////////////////////////////////////////////////////////////////////////////////////////
// local variables
////////////////////////////////////////////////////////////////////////////////////////////////////
var patientData = [];
var now = new Date().getTime();
var fs = require('fs');
var mongoClient = require('mongodb').MongoClient;
var pebble = require('./lib/pebble');
var cgmData = [];
////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
// setup http server
////////////////////////////////////////////////////////////////////////////////////////////////////
var PORT = process.env.PORT || 1337;
var server = require('http').createServer(function serverCreator(request, response) {
var nodeStatic = require('node-static');
var staticServer = new nodeStatic.Server(".");
var sys = require("sys");
// Grab the URL requested by the client and parse any query options
var url = require('url').parse(request.url, true);
if (url.path.indexOf('/pebble') === 0) {
request.with_collection = with_collection;
pebble.pebble(request, response);
return;
}
// Serve file using node-static
staticServer.serve(request, response, function clientHandler(err) {
if (err) {
// Log the error
sys.error("Error serving " + request.url + " - " + err.message);
// Respond to the client
response.writeHead(err.status, err.headers);
response.end('Error 404 - file not found');
}
});
}).listen(PORT);
////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
// setup socket io for data and message transmission
////////////////////////////////////////////////////////////////////////////////////////////////////
var io = require('socket.io').listen(server);
// reduce logging
io.set('log level', 0);
//Windows Azure Web Sites does not currently support WebSockets, so use long-polling
io.configure(function () {
io.set('transports', ['xhr-polling']);
});
var watchers = 0;
io.sockets.on('connection', function (socket) {
io.sockets.emit("now", now);
io.sockets.emit("sgv", patientData);
io.sockets.emit("clients", ++watchers);
socket.on('ack', function(alarmType, _silenceTime) {
alarms[alarmType].lastAckTime = new Date().getTime();
alarms[alarmType].silenceTime = _silenceTime ? _silenceTime : FORTY_MINUTES;
io.sockets.emit("clear_alarm", true);
console.log("alarm cleared");
});
socket.on('disconnect', function () {
io.sockets.emit("clients", --watchers);
});
});
////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
// data handling functions
////////////////////////////////////////////////////////////////////////////////////////////////////
var TZ_OFFSET_PATIENT = 8;
var TZ_OFFSET_SERVER = new Date().getTimezoneOffset() / 60;
var ONE_HOUR = 3600000;
var ONE_MINUTE = 60000;
var FIVE_MINUTES = 300000;
var FORTY_MINUTES = 2400000;
var TWO_DAYS = 172800000;
var DB = require('./database_configuration.json');
DB.url = DB.url || process.env.CUSTOMCONNSTR_mongo;
DB.collection = DB.collection || process.env.CUSTOMCONNSTR_mongo_collection;
var DB_URL = DB.url;
var DB_COLLECTION = DB.collection;
var Alarm = function(_typeName, _threshold) {
this.typeName = _typeName;
this.silenceTime = FORTY_MINUTES;
this.lastAckTime = 0;
this.threshold = _threshold;
};
// list of alarms with their thresholds
var alarms = {
"alarm" : new Alarm("Regular", 0.05),
"urgent_alarm": new Alarm("Urgent", 0.10)
};
function with_collection (fn) {
mongoClient.connect(DB_URL, function (err, db) {
if (err) throw err;
var collection = db.collection(DB_COLLECTION);
fn(err, collection);
});
}
function update() {
now = Date.now();
cgmData = [];
var earliest_data = now - TWO_DAYS;
mongoClient.connect(DB_URL, function (err, db) {
if (err) throw err;
var collection = db.collection(DB_COLLECTION);
collection.find({"date": {"$gte": earliest_data}}).toArray(function(err, results) {
results.forEach(function(element, index, array) {
if (element) {
var obj = {};
obj.y = element.sgv;
obj.x = element.date;
obj.d = element.dateString;
cgmData.push(obj);
}
});
db.close();
});
});
// wait for database read to complete, 5 secs has proven to be more than enough
setTimeout(loadData, 5000);
return update;
}
function emitAlarm(alarmType) {
var alarm = alarms[alarmType];
if (now > alarm.lastAckTime + alarm.silenceTime) {
io.sockets.emit(alarmType);
} else {
console.log(alarm.typeName + " alarm is silenced for " + Math.floor((alarm.silenceTime - (now - alarm.lastAckTime)) / 60000) + " minutes more");
}
}
function loadData() {
var treatment = [];
var mbg = [];
var actual = [];
if (cgmData) {
actual = cgmData.slice();
actual.sort(function(a, b) {
return a.x - b.x;
});
// sgv less than or equal to 10 means error code
// or warm up period code, so ignore
actual = actual.filter(function (a) {
return a.y > 10;
})
}
var actualLength = actual.length - 1;
if (actualLength > 1) {
// predict using AR model
var predicted = [];
var lastValidReadingTime = actual[actualLength].x;
var elapsedMins = (actual[actualLength].x - actual[actualLength - 1].x) / ONE_MINUTE;
var BG_REF = 140;
var BG_MIN = 36;
var BG_MAX = 400;
var y = Math.log(actual[actualLength].y / BG_REF);
if (elapsedMins < 5.1) {
y = [Math.log(actual[actualLength - 1].y / BG_REF), y];
} else {
y = [y, y];
}
var n = Math.ceil(12 * (1 / 2 + (now - lastValidReadingTime) / ONE_HOUR));
var AR = [-0.723, 1.716];
var dt = actual[actualLength].x;
for (i = 0; i <= n; i++) {
y = [y[1], AR[0] * y[0] + AR[1] * y[1]];
dt = dt + FIVE_MINUTES;
predicted[i] = {
x: dt,
y: Math.max(BG_MIN, Math.min(BG_MAX, Math.round(BG_REF * Math.exp(y[1]))))
};
}
//TODO: need to consider when data being sent has less than the 2 day minimum
// consolidate and send the data to the client
patientData = [actual, predicted, mbg, treatment];
io.sockets.emit("now", now);
io.sockets.emit("sgv", patientData);
// compute current loss
var avgLoss = 0;
for (var i = 0; i <= 6; i++) {
avgLoss += 1 / 6 * Math.pow(log10(predicted[i].y / 120), 2);
}
if (avgLoss > alarms['urgent_alarm'].threshold) {
emitAlarm('urgent_alarm');
} else if (avgLoss > alarms['alarm'].threshold) {
emitAlarm('alarm');
}
}
}
// get data from database and setup to update every minute
function kickstart ( ) {
update( );
return update;
}
setInterval(kickstart(), ONE_MINUTE);
////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
// helper functions
////////////////////////////////////////////////////////////////////////////////////////////////////
function log10(val) { return Math.log(val) / Math.LN10; }
////////////////////////////////////////////////////////////////////////////////////////////////////