Augmented Reality, Windows 8, and Cloud Computing – Part 3: Cloud Back-End

Title	Description	Link
Augmented Reality applications need a Web Service Back-End. Here is a 90-Day No obligation, totally free offer to use Windows Azure as your web service for Windows 8 Clients.	You get: Compute / 750 small compute hours per month, Web sites / 10 web sites, Mobile services / 10 mobile services, Relational database / 1 SQL database, SQL reporting / 100 hours per month, Storage / 35GB with 50,000,000 storage transactions, Bandwidth / unlimited inbound & 25GB outbound, CDN / 20GB outbound with 500,000 transactions, Cache / 128MB, Service bus / 1,500 relay hours and 500,000 messages	http://www.microsoft.com/click/services /Redirect2.ashx?CR_CC=200114759
Step 0: What we will build. Augmented Reality, Windows 8, and Cloud Computing–How to implement with real code	High level introduction to our finished application.	http://blogs.msdn.com/b/brunoterkaly/archive/2012 /11/05/step-0-what-we-will-build- augmented-reality-windows-8-and-cloud-computing-how-to-implement-with-real-code.aspx#
Step 1–Augmented Reality, Windows 8, and Cloud Computing–How to implement with real code	Introduction. What is Augmented Reality	http://blogs.msdn.com/b/brunoterkaly/archive/2012/10/29/ step-1-augmented-reality-windows-8-and-cloud-computing- how-to-implement-with-real-code.aspx#
Step 2–Augmented Reality, Windows 8, and Cloud Computing–How to implement with real code	Building the first part of our Azure back-end.	http://blogs.msdn.com/b/brunoterkaly/archive/2012/10/30/ step-2-augmented-reality-windows-8-and- cloud-computing-how-to-implement-with-real-code.aspx#
Step 3–Augmented Reality, Windows 8, and Cloud Computing–How to implement with real code (Implementing the Cloud Back-End)	This post provides all source code and explanation for the Azure back-end. This is the back-end for the augmented reality Windows 8 Client.	http://blogs.msdn.com/b/brunoterkaly/archive/2012/11/05 /step-3-augmented-reality-windows-8-and-cloud-computing-how- to-implement-with-real-code-implementing-the-cloud-back-end.aspx#
Step 4–Augmented Reality, Windows 8, and Cloud Computing–How to implement with real code ...	This post provides all source code and explanation for the Windows 8 Client (Augmented Reality Demo). The augmented reality Windows 8 Client calls into the Azure back-end described in step 3 above.	http://blogs.msdn.com/b/brunoterkaly/archive/2012/11/06/ step-4-augmented-reality-windows-8-and-cloud-computing-how-to-implement-with-real-code-implementing-the- windows-8-client.aspx#
Source Code - Web Service Back End	This is the Windows Azure Project that Windows 8 Clients call into	http://sdrv.ms/Qoqb1J
Source Code - Windows 8 Client	This is the Augmented Reality Windows 8 Client	http://sdrv.ms/T38uBC

1. I have completed the code. Now it is time to blog about it.
2. Notice that it has augmented reality data overload on top of a live photo
3. It also has a satellite image
4. You can use the GPS simulator to change locations
   • My system doesn't have a GPS device and yours probably does not either
5. The information displayed is a mash-up of the Google Maps and information from the National Oceanic and Atmospheric Administration
6. I will provide all source code.

1. A little better resolution to see what is happening.

1. It is hosted in a Microsoft Data Center
2. The image above is running locally (in an emulator)
3. This running application can be scaled to meet any demand by Windows 8 clients
4. The style of Azure application is (MVC Web API), described in future posts

1. We will build a Windows 8 Client in a future post
   • That is where the augmented reality is actually taking place
2. Our front end web services tier supports our Windows 8 Client
   • We will deploy this tier to a Microsoft Data Center
3. The Application Services Tier will be Google Maps and the National Oceanic Atmospheric Agency (NOAA)
   • This could just as easily be Bing Maps
   • In fact, there are many, many options here http://www.programmableweb.com/
4. This could be architected for even greater scale.
   • You could leverage message queues and background processes (worker roles)
5. It does currently leverage threading for parallel look ups of data mash-ups
   • This means I call Google Maps and NOAA at the same time using .NET Tasks
6. The next step is to finish building the cloud server.
7. From there I will show the code behind the Windows 8 client

1. In Step 2 you could see how to create:
   • A Windows Azure Cloud Project with:

  1 MVC 4 Web Role

  Web Role Type = ASP.NET Web API

1. It is a Windows Azure Cloud app
2. It was previously blogged about here
   • Step 2 - Augmented Reality, Windows 8, and Cloud Computing - How to implement with real code
   • http://blogs.msdn.com/b/brunoterkaly/archive/2012/10/30/step-2-augmented-reality-windows-8-and-cloud-computing-how-to-implement-with-real-code.aspx
3. But we need to add more to this project.

1. You can see one solution with two projects:
   • Project 1: Location_WebRole
     • This is where we do all the work, adding code
   • Project 2: LocationWebService
     • This is the configuration project that allows us to scale our application once we deploy it to the cloud.

1. We are going to do 3 things here:
   • Modify Existing Files
   • Add a folder to hold our code
   • Add new classes
2. Modify Files
   • ValuesController.cs
3. Add Folder
   • HelperObjects
4. Add classes (HelperObjects)
   • CityFromGps.cs
   • DataExtractor.cs
   • LocationInfo.cs

1. This is the entry point for clients making http calls
2. We only need one method in there.
   • The Get() method responds to Windows 8 client requests

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using Location_WebRole.HelperObjects;

namespace Location_WebRole.Controllers
{
    public class ValuesController : ApiController
    {
        // location contains lat/long, "37.788345,-122.404679", for example
        public LocationInfo Get(string location)
        {
            string[] columns = location.Split(',');
            CityFromGps city = new CityFromGps();
            return city.ReverseGeoLoc(columns[1], columns[0]);
        }
 
    }
}

1. This class does most of the hard work.
2. It uses concurrent programming techniques to conduct data mash-ups.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Formatting;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using Location_WebRole.HelperObjects;

namespace Location_WebRole.Controllers
{
    // My custom string manipulator. Nows how to parse all the XML structures
    public class CityFromGps
    {

        // Method that does all the lookups based on longitude and latitude.
        public LocationInfo ReverseGeoLoc(string longitude, string latitude)
        {
            // Return data is LocationInfo
            LocationInfo loc_info = new LocationInfo();
            DataExtractor de = new DataExtractor(); // a helper class to make this threading code readable
            loc_info.longitude = longitude;
            loc_info.latitude = latitude;

            try
            {
                //
                // Get Data
                //

                XmlDocument[] xmldocs = new XmlDocument[3] { new XmlDocument(), new XmlDocument(), new XmlDocument() };

                Task<string>[] tasks = new Task<string>[3]
                {
                    Task<string>.Factory.StartNew(() =>
                        {
                            xmldocs[0].Load("http://maps.googleapis.com/maps/api/elevation/xml?locations=" + latitude + "," + longitude + "&sensor=false");
                            XmlNodeList weatherList = xmldocs[0].SelectNodes("//ElevationResponse/result");
                            loc_info.elevation = (Convert.ToDouble(weatherList[0]["elevation"].InnerText) * 3.2808399).ToString();
                            return "";
                        }),
                    Task<string>.Factory.StartNew(() =>
                        {
                            // Get Transit and Neighborhood Info
                            xmldocs[1].Load(string.Format("http://maps.googleapis.com/maps/api/geocode/xml?latlng={0},{1}&sensor=false", latitude, longitude));
                            loc_info.bus_and_neighborhood = de.GetTransitAndNeighborhood(xmldocs[1]);
                            return "";
                        }),
                    Task<string>.Factory.StartNew(() =>
                        {
                            // Get Weather Info
                            xmldocs[2].Load(string.Format("http://graphical.weather.gov/xml/sample_products/browser_interface/ndfdXMLclient.php?lat={0}&lon={1}&product=time-series&maxt=maxt&mint=mint", latitude, longitude));
                            loc_info.max_temp = de.GetMaxTemp(xmldocs[2]);
                            loc_info.min_temp = de.GetMinTemp(xmldocs[2]);
                            return "";
                        })
                };
                //Block until all tasks complete. This is much faster.
                Task.WaitAll(tasks);
                return loc_info;
            }
            catch (Exception ex)
            {
                loc_info.error = "(Location lookup failed: ) " + ex.Message;
                return loc_info;
            }

        }

    }

}

1. DataExtractor.cs abstracts the complexity of parsing XML and getting the answers we need
   • Such as max temp, min temp, elevation, etc
2. LocationInfo.cs represents the data going back to the Windows 8 client
   • It is in JSON format.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Xml;

namespace Location_WebRole.Controllers
{
    public class DataExtractor
    {
        public string GetTransitAndNeighborhood(XmlDocument doc)
        {

            string result = "";
            bool foundneighborhood = false;
            bool foundbus = false;
            XmlNodeList xnList = doc.SelectNodes("//GeocodeResponse/result/address_component");
            foreach (XmlNode xn in xnList)
            {
                try
                {
                    switch (xn["type"].InnerText)
                    {
                        //Add whatever you are looking for below
                        case "bus_station":
                            {
                                if (foundbus)
                                    break;
                                if (result != "")
                                    result += ", ";
                                result += "Bus: " + xn["long_name"].InnerText;
                                foundbus = true;
                                break;
                            }

                        case "neighborhood":
                            {
                                if (foundneighborhood)
                                    break;
                                if (result != "")
                                    result += ", ";
                                result += "Neighborhood: " + xn["long_name"].InnerText + " (" + xn["short_name"].InnerText + ")";
                                foundneighborhood = true;
                                break;
                            }

                        default:
                            break;
                    }
                }

                catch (Exception e)
                {
                }
            }

            return result;
        }

        internal string GetMaxTemp(XmlDocument doc)
        {
            XmlNodeList xnList = doc.SelectNodes("//dwml/data/parameters/temperature");
            return xnList[0]["value"].InnerText;  // offset 0 is max temps
        }
        internal string GetMinTemp(XmlDocument doc)
        {
            XmlNodeList xnList = doc.SelectNodes("//dwml/data/parameters/temperature");
            return xnList[1]["value"].InnerText;  // offset 1 is min temps
        }
    }

}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Formatting;
using System.Web;

namespace Location_WebRole.HelperObjects
{
    public class LocationInfo
    {
        // Data we will lookup
        public string latitude { get; set; }
        public string longitude { get; set; }
        public string elevation { get; set; }
        public string bus_and_neighborhood { get; set; }
        public string max_temp { get; set; }
        public string min_temp { get; set; }
        public string error { get; set; }
    }
}