app.listen(3000)与app是不一样的

前者是server代码如下

Server {
  domain: null,
  _events:
   { request:
      { [Function]
        domain: undefined,
        _events: [Object],
        _maxListeners: undefined,
        setMaxListeners: [Function: setMaxListeners],
        getMaxListeners: [Function: getMaxListeners],
        emit: [Function: emit],
        addListener: [Function: addListener],
        on: [Function: addListener],
        once: [Function: once],
        removeListener: [Function: removeListener],
        removeAllListeners: [Function: removeAllListeners],
        listeners: [Function: listeners],
        listenerCount: [Function: listenerCount],
        init: [Function: init],
        defaultConfiguration: [Function: defaultConfiguration],
        lazyrouter: [Function: lazyrouter],
        handle: [Function: handle],
        use: [Function: use],
        route: [Function: route],
        engine: [Function: engine],
        param: [Function: param],
        set: [Function: set],
        path: [Function: path],
        enabled: [Function: enabled],
        disabled: [Function: disabled],
        enable: [Function: enable],
        disable: [Function: disable],
        checkout: [Function],
        connect: [Function],
        copy: [Function],
        delete: [Function],
        get: [Function],
        head: [Function],
        lock: [Function],
        'm-search': [Function],
        merge: [Function],
        mkactivity: [Function],
        mkcalendar: [Function],
        mkcol: [Function],
        move: [Function],
        notify: [Function],
        options: [Function],
        patch: [Function],
        post: [Function],
        propfind: [Function],
        proppatch: [Function],
        purge: [Function],
        put: [Function],
        report: [Function],
        search: [Function],
        subscribe: [Function],
        trace: [Function],
        unlock: [Function],
        unsubscribe: [Function],
        all: [Function: all],
        del: [Function],
        render: [Function: render],
        listen: [Function: listen],
        request: [Object],
        response: [Object],
        cache: {},
        engines: {},
        settings: [Object],
        _eventsCount: 1,
        locals: [Object],
        mountpath: '/',
        _router: [Object] },
     connection: [Function: connectionListener],
     clientError: [Function] },
  _eventsCount: 3,
  _maxListeners: undefined,
  _connections: 0,
  _handle:
   TCP {
     _externalStream: {},
     fd: 11,
     reading: false,
     owner: [Circular],
     onread: null,
     onconnection: [Function: onconnection],
     writeQueueSize: 0 },
  _usingSlaves: false,
  _slaves: [],
  _unref: false,
  allowHalfOpen: true,
  pauseOnConnect: false,
  httpAllowHalfOpen: false,
  timeout: 120000,
  _pendingResponseData: 0,
  _connectionKey: '6::::3000' }

后者还没有实例化算是一个类：代码如下：

{ [Function]
  domain: undefined,
  _events: { mount: [Function: onmount] },
  _maxListeners: undefined,
  setMaxListeners: [Function: setMaxListeners],
  getMaxListeners: [Function: getMaxListeners],
  emit: [Function: emit],
  addListener: [Function: addListener],
  on: [Function: addListener],
  once: [Function: once],
  removeListener: [Function: removeListener],
  removeAllListeners: [Function: removeAllListeners],
  listeners: [Function: listeners],
  listenerCount: [Function: listenerCount],
  init: [Function: init],
  defaultConfiguration: [Function: defaultConfiguration],
  lazyrouter: [Function: lazyrouter],
  handle: [Function: handle],
  use: [Function: use],
  route: [Function: route],
  engine: [Function: engine],
  param: [Function: param],
  set: [Function: set],
  path: [Function: path],
  enabled: [Function: enabled],
  disabled: [Function: disabled],
  enable: [Function: enable],
  disable: [Function: disable],
  checkout: [Function],
  connect: [Function],
  copy: [Function],
  delete: [Function],
  get: [Function],
  head: [Function],
  lock: [Function],
  'm-search': [Function],
  merge: [Function],
  mkactivity: [Function],
  mkcalendar: [Function],
  mkcol: [Function],
  move: [Function],
  notify: [Function],
  options: [Function],
  patch: [Function],
  post: [Function],
  propfind: [Function],
  proppatch: [Function],
  purge: [Function],
  put: [Function],
  report: [Function],
  search: [Function],
  subscribe: [Function],
  trace: [Function],
  unlock: [Function],
  unsubscribe: [Function],
  all: [Function: all],
  del: [Function],
  render: [Function: render],
  listen: [Function: listen],
  request: IncomingMessage { app: [Circular] },
  response: ServerResponse { app: [Circular] },
  cache: {},
  engines: {},
  settings:
   { 'x-powered-by': true,
     etag: 'weak',
     'etag fn': [Function: wetag],
     env: 'development',
     'query parser': 'extended',
     'query parser fn': [Function: parseExtendedQueryString],
     'subdomain offset': 2,
     'trust proxy': false,
     'trust proxy fn': [Function: trustNone],
     view: [Function: View],
     views: '/Users/Amanda/Downloads/aa/blog/views',
     'jsonp callback name': 'callback' },
  _eventsCount: 1,
  locals:
   { settings:
      { 'x-powered-by': true,
        etag: 'weak',
        'etag fn': [Function: wetag],
        env: 'development',
        'query parser': 'extended',
        'query parser fn': [Function: parseExtendedQueryString],
        'subdomain offset': 2,
        'trust proxy': false,
        'trust proxy fn': [Function: trustNone],
        view: [Function: View],
        views: '/Users/Amanda/Downloads/aa/blog/views',
        'jsonp callback name': 'callback' } },
  mountpath: '/',
  _router:
   { [Function: router]
     params: {},
     _params: [],
     caseSensitive: false,
     mergeParams: undefined,
     strict: false,
     stack: [ [Object], [Object], [Object] ] } }

另外app.createServer()此方法已经被废除；属于旧代码；websocket要监听服务器，监听实例化得app，即第一种server；