ObSy

atomic ObjectSync across nodeJS processes

The idea behind ObSy is that there are many cases where one has different nodeJS processes that need to share 'memory'. ObSy greatly simplifies sharing a namespace/object between processes by turning the task into ONE LINE OF CODE.

how ObSy works

ObSy uses the observed library (the new/upcoming ECMA harmony Object.observe method) to handle changes to a local namespace. Those changes are then sent to a redis instance for persistence and, via publish/subscribe, to other processes that registered the same namespace. Changes are encoded, so that they are (pseudo-) atomic, meaning that changes to a deep property do not require syncing the complete object.

limitations

• Functions are not synced (no plan of supporting that any time soon).
• Special objects (using non-standard constructors like e.g. mongoDB ObjectID, ...) are not synced correctly. I am planning to include a 'plugin' system that will allow anybody to handle special object types.
• when using a direct set to the observed namespace will simply wipe the ObSy handler and thus break the sync.

requirements

ObSy needs nodeJS 0.11+ to work (harmony required to allow Object.observe) and a redis instance reachable from all processes that want to sync the object

planned features

• plugin system for object constructor helpers
• option to use passive publishing via redis' built-in Redis Keyspace Notifications

version

0.02 : ObSy is really young and innocent. it's hardly tested and not at all optimized. better test coverage is next on the ToDo list (see issues).

installing

npm install obsy

tests

make

example

var ObSy = require('obsy');
var someParentNamespace = {
	syncedObject: {}
};
var myObjectSync = new ObSy('theNameOfYourSyncGroup', someParentNamespace.syncedObject);

demo

assuming you have n installed AND screen / multiple terminals running AND a local redis instance :

$ cd demo
$ n use 0.11.12 --harmony node0.js
// switch to new terminal quickly !
$ n use 0.11.12 --harmony node1.js
// with debug active you will see both nodes syncing the demo namespace ... 
// kind of feels like magic to me ;)