Executive Summary

The Environment

It is highly recommended that you use your red account for this project rather than your own computer. Since we will be using CLI (the command-line interface) for this project, it is very easy to work remotely by ssh'ing to your account. To that end, use your favorite non-GUI editor (such as nano, vim, or emacs) to edit your source files. Once you are fully comfortable with creating Node.js services, you can download the needed packages to your own machine and deploy on your AWS EC2 instance.

To create a Node.js project named projC, issue this command:

  nodeGo projC

  node index.js

Since index.js is intended to instantiate a service, the above command will block until you press ^C. Any logging on standard output (done in JavaScript via the console.log function) will appear under the above command along with any exceptions thrown.

The Services

1. GeoNode: This service is the Node counterpart of the Java GeoWeb service of Project-B and the Stateful service of Project-A. It receives two URL-encoded parameters lat and lon containing the GPS coordinates of a place on Earth. If this is the first time this client has made such a request then the return would be the text/plain payload "RECEIVED". If not, then the return would be the text/plain payload "The distance from (lat1,lon1) to (lat2,lon2) is XXX", where XXX is the geodesic distance between the previous place (sent in the last request) and the current one (sent in this request). This can continue (to a 3rd, 4th, ... places) as long as the requests are made within the same session. All computations must be made by delegating to the TCP Geo service of Project-A; i.e. this Node service does not do any math.
2. Catalog: This service receives one URL parameter id containing an integer and returns the id and name of the row corresponding to that id in the Category table of the Models_R_US.db database (which resides in ~/4413/pkg/sqlite). The return should be mimed as "application/json" in the response's content type. If the id parameter is missing then the return should be an array of json objects for all rows in the table. Here is an example of the response when the request parameter id is 2:

       [{"id":2,"name":"Classic Cars"}]

3. Trip: This service receives two URL parameters from and to containing the start and end addresses of a trip. It returns the optimal distance (in km) and time (in minutes) between them given the current traffic conditions. To get this information, connect to your GCP (Google Cloud Platform) account at https://maps.googleapis.com/maps/api/distancematrix/json and pass the following parameters: origins containing the from address, destinations containing the to address, key containing your API key, and departure_time=now to factor in the current traffic conditions.

Service Implementation

• Develop all 3 services in one project, but each in its own middleware (i.e. app.use) function . The route (URL mapping) should be the same as the service name.
• Use the following fragment as a template for your index.js:

    const port = 8000;
    const home = '/cs/home/...';
    const DB_PATH = home + '/4413/pkg/sqlite/Models_R_US.db';
  
    const net = require('net');
    const https = require('https');
    const express = require('express');
    const session = require('express-session');
  
    var app = express();
    var sqlite3 = require('sqlite3').verbose();
    var db = new sqlite3.Database(DB_PATH);
    app.enable('trust proxy');
  
    // Testing middleware for url mapping route:  http://host:port/Test?x=123
    app.use('/Test', function(req, res)
    {
       res.writeHead(200, { 'Content-Type': 'text/html'});
       res.write("Hello ... this is EECS4413/Fall19 Tester! ");
       res.end("You sent me: " + req.query.x);
    });
  
  /*
    app.use(session(
    {
      secret: "mine",
      proxy: true,
      resave: true,
      saveUninitialized: true
    }));
  
    app.use('/GeoNode', function(req, res)
    {
        ...
    });  
  
    app.use('/Catalog', function(req, res)
    {
        ...
    });
  
    app.use('/Trip', function(req, res)
    {
        ...
    });
  */
      
    // --------------------------------------SERVER
    var server = app.listen(port, function()
    {
      var host = server.address().address;
      var port = server.address().port;
      console.log('Listening at http://%s:%d', host, port);
    });

Testing & Deployment

Persist Your Work