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Sessions

mde edited this page · 14 revisions

Session data-stores

Geddy has sessions built in, and offers a number of different ways to persist session-data:

  • Memory (the default): useful mostly for development. Session-data is saved at the worker-process level, so in-memory sessions cannot be used with a Geddy app and multiple worker-processes. Also, all sessions disappear when the app is restarted.

  • Cookie: Session-data is passed back and forth in (encrypted) cookies in the request/response. Sessions will persist when the app restarts, but the amount of data you can save in a session is much more limited.

  • Memcache: Requires a Memcache server or cluster. Uses Arnout Kazemier's 'memcached' module.

  • Redis: Requires a Redis server or cluster. Uses Matt Ranney's 'redis' module.

You will probably want to develop with in-memory sessions, and use cookie, Memcache, or Redis sessions for production (depending on how much data you want to save in the session).

Using sessions

The session-object is available on the Geddy controller-instance, and has a get and set method. Here's an example of an incrementing counter saved in the session:

var Main = function () {
  this.index = function (req, resp, params) {
    var counter = this.session.get('counter');
    if (!counter) {
      counter = 0;
    }
    counter++;
    this.session.set('counter', counter);
    geddy.log.debug(counter);
    this.respond(counter, {
      format: 'txt'
    });
  };
};

exports.Main = Main;

Session-data is saved into the data-store at the end of the request/response cycle, before the response is completed. Any I/O required (depending on the specific data-store) is performed asynchronously.

Session configuration

Each type of data-store will have its own specific config-properties, but there are a few that are common to all types:

  • 'store': The type of data-store (e.g., 'memcache', 'cookie'). Default is 'memory'.
  • 'key': The name used for the session-identifier cookie. Default is 'sid'.
  • 'expiry': How long a session will last (in seconds) if it goes unrefreshed. Default is two weeks.

Other properties are data-store specific.

Sample configurations

Memcache

// 'servers' is your array of Memcache servers.
, sessions: {
    store: 'memcache'
  , servers: ['127.0.0.1:11211']
  , key: 'sid'
  , expiry: 14 * 24 * 60 * 60

Redis

// 'server' is your Redis server.                                                     
, sessions: {                                                                         
    store: 'redis'                                                                    
  , server: {                                                                         
        host : "127.0.0.1"                                                            
      , port : 6379                                                                   
      , opts : {}                                                                     
      , auth : "megasecret" // [optional] password                                    
      , ns  : "sess:" // redis key prefix                                             
  }                                                                                   
  , key: 'sid'                                                                        
  , expiry: 14 * 24 * 60 * 60  
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