Wednesday, June 06, 2007

All the Web is a Stage

Google Gears' WorkerPool - Message Passing, Shared Nothing Concurrency

By now, you‘ve probably already seen Google Gears, Google's solution for dragging AJAX applications offline. The one thing that jumped out at me was their WorkerPool component. This is a very nice solution for concurrency in Javascript.
In short: if you have any long running task, you can create a WorkerPool which is basically group of Javascript processes Note: they're not threads! The workers in a WorkerPool share nothing with each other, which makes them like OS processes or Erlang's lightweight processes (actually, they're more like the latter, as they're likely to run in the same address space).

And now guess, how these workers, these processes, communicate? Yep: messages, formatted as strings. Important to remember: if you format objects with as JSON strings, you can even send objects and structures along. The handler that receives messages also gets the ID of the sender, so if the sender implements a handler too, it‘s possible to return results asynchronously.

If you‘re reminded of Erlang or the old Actor concept you‘re right. I wonder what the Google Apps will do with this new concurrency approach (well, new for Javascript… yes I‘m ignoring Javascript Rhino).

I still hope that AJAX will die a quick death, like Java Applets, just for being so damn ugly and horrible to implement. But… things like this tell me that this will probably not happen. Good ideas like Google Gears will help paint over the ugly details of a solution, and it‘s all hip now, so it's easy to ignore many of the problems.


The same idea is also being implemented in Scala with their Actors.
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