Friday, July 25, 2014

The Hunt for the Chocolate Thief (Part 2) - Putting IBM Bluemix, Cloudant, and a Raspberry Pi to good use

I am still on the hunt for the mean chocolate thief, kind of. In the first part I covered the side of the Raspberry Pi and uploading data to Cloudant. I showed how to set up an infrared motion sensor and a webcam with the RPi, capture a snapshot and secure the image and related metadata in a Cloudant database on the IBM Bluemix Platform-as-a-service (PaaS) offering. In this part I am going to create a small reporting website with Python, hosted as a IBM Bluemix service.

Similar to an earlier weather project, I use Python as scripting language. On Bluemix, which is based on Cloud Foundry, this means to "bring your own buildpack". I already described the necessary steps which is to tell Bluemix how to create the runtime environment and install the needed Python libraries. So how do I access the incident data, i.e., the webcam snapshots taken by the Raspberry Pi when someone is in front of the infrared motion sensor? Let's take a look at the script:

 import os  
 from flask import Flask,redirect  
 import urllib  
 import datetime  
 import json  
 import couchdb  
 app = Flask(__name__)  
 # couchDB/Cloudant-related global variables  
 #get service information if on Bluemix  
 if 'VCAP_SERVICES' in os.environ:  
   couchInfo = json.loads(os.environ['VCAP_SERVICES'])['cloudantNoSQLDB'][0]  
   couchServer = couchInfo["credentials"]["url"]  
   couch = couchdb.Server(couchServer)  
 #we are local  
   with open("cloudant.json") as confFile:  
    couchServer = couchInfo["credentials"]["url"]  
    couch = couchdb.Server(couchServer)  
 # access the database which was created separately  
 db = couch['officecam']  
 def index():  
   # build up result page  
   page +='<h1>Security Incidents</h1>'  
   # Gather information from database about which city was requested how many times  
   page += '<h3>Requests so far</h3>'  
   # We use an already created view  
   for row in db.view('incidents/incidents'):  
     page += 'Time: <a href="/incident/'+str(row.key["id"])+'">'+str(row.key["ts"])+'</a><br/>'  
   # finish the page structure and return it  
   return page  
 def incident(id):  
   # build up result page  
   page='<title>Incident Detail</title>'  
   page +='<h1>Security Incident Details</h1>'  
   # Gather information from database about the incident  
   page += '<br/>Incident at date/time:'+str(doc["timestamp"])  
   page += '<br/>reported by "'+doc["creater"]+'" at location "'+doc["location"]+'"'  
   page += '<br/>Photo taken:<br/><img src="/image/'+id+'" />'  
   # finish the page structure and return it  
   return page  
 def image(id):  
   #redirecting the request to Cloudant for now, but should be hidden in the future  
   return redirect(couchServer+'/officecam/'+id+'/cam.jpg')    
 port = os.getenv('VCAP_APP_PORT', '5000')  
 if __name__ == "__main__":'', port=int(port))  

Overview of Security Incidents
The setup phase includes reading in access data for the Cloudant database server. Either that information is taken from a Bluemix environment variable or provided in a file "cloudant.json" (similar to what I did on the RPi). The main part of the script defines three routes, i.e., how to react to certain URL requests. The index page (index()) returns an overview of all recorded incidents, an incident detail page (incident(id)) fetches the data for a single event and embeds the stored webcam image into the generated page, and the last route (image(id)) redirects the request to Cloudant.

 Looking at how the index page is generated, you will notice that a predefined Cloudant view (secondary index) named "incidents/incidents" is evaluated. It is a simple reduce function that sorts based on the timestamp and document ID and returns just that composite key.

Incident Detail: Hadoop involved?
function(doc) {
    if (doc.type == "oc")
       emit({"ts" : doc.timestamp, "id" : doc._id}, 1);

Then I access the timestamp information and generate the list as shown in the screenshot above.

The incident detail page has the document ID as parameter. This makes it simple to retrieve the entire document and print the details. The webcam image is embedded. So who got my chocolate? Take a look. It looks like someone who got a free copy of "Hadoop for Dummies" at the IDUG North America conference.

Maybe another incident will shed light into this mystery. Hmm, looks like someone associated to the "Freundeskreis zur Förderung des Zeppelin Museums e.V." in Friedrichshafen. I showed the pictures to my wife and she was pretty sure who took some chocolate. I should pay more attention when grabbing another piece of my chocolate and should more closely watch how much I am eating/enjoying.
Zeppelin Brief seen at robbery

Have a nice weekend (and remember to sign up for a free Bluemix account)!