Installing NodeJS on Centos 6.6.

Installing nodejs and npm on centos is very simple.

 [nodejs-admin@nodejs ~]$ sudo su
 [nodejs-admin@nodejs ~]# curl -sL https://rpm.nodesource.com/setup | bash -
 [nodejs-admin@nodejs ~]# yum install -y nodejs

Installing gcc-c++ and make.

 [nodejs-admin@nodejs ~]$ sudo yum install gcc-c++ make
 [sudo] password for nodejs-admin: 
 Loaded plugins: fastestmirror, refresh-packagekit, security
 Setting up Install Process
 Loading mirror speeds from cached hostfile
  * base: mirrors.123host.vn
  * epel: ftp.cuhk.edu.hk
  * extras: centos-hn.viettelidc.com.vn
  * updates: mirrors.vonline.vn
 Package 1:make-3.81-20.el6.x86_64 already installed and latest version
 Resolving Dependencies
 ...           

 Complete!

Later on we will need kafka-node lets install that as well.

 [nodejs-admin@nodejs ~]$ sudo npm install kafka-node
 [sudo] password for nodejs-admin: 

 > snappy@3.0.6 install /home/nodejs-admin/node_modules/kafka-node/node_modules/snappy
 > node-gyp rebuild

 gyp WARN EACCES user "root" does not have permission to access the dev dir "/root/.node-gyp/0.10.36"
 gyp WARN EACCES attempting to reinstall using temporary dev dir "/home/nodejs-admin/node_modules/kafka-node/node_modules/snappy/.node-gyp"
 make: Entering directory `/home/nodejs-admin/node_modules/kafka-node/node_modules/snappy/build'
   CXX(target) Release/obj.target/snappy/deps/snappy/snappy-1.1.2/snappy-sinksource.o
   CXX(target) Release/obj.target/snappy/deps/snappy/snappy-1.1.2/snappy-stubs-internal.o
   CXX(target) Release/obj.target/snappy/deps/snappy/snappy-1.1.2/snappy.o
   AR(target) Release/obj.target/deps/snappy/snappy.a
   COPY Release/snappy.a
   CXX(target) Release/obj.target/binding/src/binding.o
   SOLINK_MODULE(target) Release/obj.target/binding.node
   SOLINK_MODULE(target) Release/obj.target/binding.node: Finished
   COPY Release/binding.node
 make: Leaving directory `/home/nodejs-admin/node_modules/kafka-node/node_modules/snappy/build'
 kafka-node@0.2.18 node_modules/kafka-node
 ├── buffer-crc32@0.2.5
 ├── retry@0.6.1
 ├── node-uuid@1.4.1
 ├── async@0.7.0
 ├── lodash@2.2.1
 ├── debug@2.1.1 (ms@0.6.2)
 ├── binary@0.3.0 (buffers@0.1.1, chainsaw@0.1.0)
 ├── node-zookeeper-client@0.2.0 (async@0.2.10, underscore@1.4.4)
 ├── buffermaker@1.2.0 (long@1.1.2)
 └── snappy@3.0.6 (bindings@1.1.1, nan@1.5.3)
 [nodejs-admin@nodejs ~]$ ls

Lets do a test.

Create a script called example.js with below code.

 var http = require('http');
 http.createServer(function (req, res) {
   res.writeHead(200, {'Content-Type': 'text/plain'});
   res.end('Hello World\n');
 }).listen(1337, '127.0.0.1');
 console.log('Server running at http://127.0.0.1:1337/');

Lets start the server on a terminal.

 [nodejs-admin@nodejs nodejs]$ node example.js 
 Server running at http://127.0.0.1:1337/

Hit the URL from the browser and We can see Hello World.
So we are all set.

NodeJS is Ready.

Lets make some simple changes to exsisting script to handle JSON.

Here is a simple script to handle JSON data.

 //    Getting some 'http' power
 var http=require('http');

 //    Setting where we are expecting the request to arrive.
 //    http://localhost:8125/upload
 var request = {
                 hostname: 'localhost',
                 port: 8125,
                 path: '/upload',
                 method: 'GET'
             };

 //    Lets create a server to wait for request.
 http.createServer(function(request, response) 
 {
     //    Making sure we are waiting for a JSON.
     response.writeHeader(200, {"Content-Type": "application/json"});

     //    request.on waiting for data to arrive.
     request.on('data', function (chunk) 
     {
         //    CHUNK which we recive from the clients
         //    For out request we are assuming its going to be a JSON data.
         //    We print it here on the console. 
         console.log(chunk.toString('utf8'))
     });
     //end of request
     response.end();
 //    Listen on port 8125
 }).listen(8125);

Lets fire up the script.

 [nodejs-admin@nodejs nodejs]$ node node_recv_json.js 

On a new terminal send some request to our script. Our script is listening on 8125 port.

 [nodejs-admin@nodejs nodejs]$ curl -H "Content-Type: application/json" -d '{"username":"xyz","password":"xyz"}' http://localhost:8125/upload

You will see the message received on the script terminal.

 [nodejs-admin@nodejs nodejs]$ node node_recv_json.js 
 {"username":"xyz","password":"xyz"}

Now we are all set to do some RND.

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