process big files in node js, read xml files

node_big_xml_files.js

/**
* full article at 
* http://theraaz.com/javascript/how-to-process-big-files-in-node-js
*/

var bigFileUrl = "http://www.site-containing-big-data/api";
request.get(bigFileUrl)
  .on('error', function(errReq) {
      console.log('error while reading from big site : ', errReq);
      // do something here if you want to throw an exception or something else
  }).on('end', function(){
      /*
      * once all the data received and saved successfully in bigfile.xml 
      * request will fire this event.
      */
      console.log('got from big site, now processing');
      
      // now read that file with xml-stream
      
      var XmlStream = require('xml-stream') ;
      var stream=fs.createReadStream('bigfile.xml');
      xml = new XmlStream(stream);
      // item is the node that contains data. check sample xml below
      xml.on('endElement: item', function(item) {
          // it will read all the objects one at a time and here you can process that object,
          // if a lot of processing required, you can call xml.pause() and xml.resume() method available in xml-stream package
      });
      xml.on('end', function(){
          // when processing finished for all objects/items in that file
          });
      });
  })
  .pipe(fs.createWriteStream('bigfile.xml'));
  // this pipe method will stream data to bigfile.xml 
  
  
  /**
   * <items>
   *    <item>
   *      <name>alex</name>
   *      <age>23</age>
   *    </item>
   *    <item>
   *      <name>john</name>
   *      <age>17</age>
   *    </item>
   *    <item>
   *      <name>smona</name>
   *      <age>12</age>
   *    </item>
   *    <item>
   *      <name>smith</name>
   *      <age>34</age>
   *    </item>
   * </items>
   * /