Accessing Cassandra through NodeJS

Below are the steps to enable web access of Cassandra DB
--------------------------------------------------------

1. install Cassandra DB from apache cassandra
2. install nodejs
3. install the required modules
   a) http       - npm install http
   b) cassandra  - npm install cassandra-driver
   c) express    - npm install express
   d) body-parser - npm install bodyParser
4. create a nodejs file

   E.g. myserver.js

5. now add following lines

   a) first need to list the required modules

      var express = require('express');
      var bodyParser = require('body-parser');
      var cassandra = require('cassandra-driver');

      Note: Put actual path of the driver if not in current directory. E.g
            'D:\\Node-modules\\express').  \\ is required

   b) declare a cassandra client and connect to cluster

      var client = new cassandra.client({contactPoints:['127.0.0.1']});
      client.connect(function(err, result) {     //connect to node
         console.log('Connected');
      });

      Note-1: 127.0.0.1 can also be replaced by the actual IP address of the
              cassandra node - could be the seed node
      Note-2: the keyspace to be connected to can also be specified
              E.g. '127.0.0.1',keyspace: 'demo'

   c) Declare the variables

      var app = express();
      app.use(bodyParser.json());
      app.set('json spaces', 2);

   d) get the information

      - node information

        app.get('/metadata', function(req, res) {
            client.execute('use demo;', function(err, result) {
              if (!err) {
                   //do nothing
               }
            })
            res.send(client.hosts.slice(0).map(function (node) {
              return { address : node.address, rack : node.rack, datacenter : node.datacenter, keyspace:              
                             client.keyspace }
            }));
        });

     - list of keyspaces

       app.get('/keyspaces', function(req, res) {
           client.execute('select keyspace_name from system_schema.keyspaces;', function(err, result) {
              if(!err) {
                  res.json(result);
              }
           })
       });

     - list of tables in keyspaces

       app.get('/keyspaces/tables', function(req, res) {
           client.execute('select keyspace_name, table_name from system_schema.tables;', function(err, result) {
              if(!err) {
                  res.json(result);
              }
           })
       });

     e) start the server

        var server = app.listen(3000, function(req, response) {
            console.log("Hello World!");
        });  

        Note: the port number could be any number. 3000 is shown as example

6. run the js file - node myserver.js

7. Connect to the server - http://<ip-ofnode-where-js-running>:3000

   a) to get metadata          - http://<ip>:3000/metadata
   b) to get list of keyspaces - http://<ip>:3000/keyspaces
   c) to get list of tables    - http://<ip>:3000/keyspaces/tables
 

8. more APIs can be added as needed.