gistfile1.js

// ====================================
// Example: Nesting callbacks to produce serial requests

server.on('request', function(req, res) {
  //get session information from memcached
  memcached.getSession(req, function(session) {
    //get information from db
    db.get(session.user, function(userData) {
      //some other web service call
      ws.get(req, function(wsData) {
        //render page
        page = pageRender(req, session, userData, wsData);
        //output the response
        res.write(page);
      });
    });
  });
});    
    
// ====================================
// Example: Encapsulating within a callback

server.on('request', function(req, res) {

  var render = function(wsData) {
    page = pageRender(req, session, userData, wsData);
  };

  var getWsInfo = function(userData) {
    ws.get(req, render);
  };

  var getDbInfo = function(session) {
    db.get(session.user, getWsInfo);
  };

  var getMemCached = function(req, res) {
    memcached.getSession(req, getDbInfo);
  };

}