log4p

Today the DWR project has released version 2.0 milestone 1. The releasenotes claim the most import new feature is ‘reverse ajax’:

The biggest new feature is what we call Reverse Ajax. DWR 1.x allowed you to asynchronously call Java code from Javascript. DWR 2.0 builds on this to allow you to asynchronously call Javascript code from Java. Reverse Ajax makes writing interactive applications much easier. It can use polling or Comet (long-lived HTTP) queries.

In the past I used pushlet alike technology to get this to work, which basically keeps the response stream open to write javascript calls to the running javascript engine. Having used this technology for a couple of years to send events to connected clients I can only conclude: it doesn’t scale well / at all. Flipping through the ‘comet’ page doesn’t really convince me they solved to problem. Great they also offer polling support, which is much easier in the sense of scalability.

Some other new features include:

• support for generics (no more signatures!!)
• support for metadata in the call (will be stored in request attributes)

Looks promising, a bit of a dissapointment is:

So please do not use DWR 2.0 in a production system until we’ve had more testing and inspections.

In the paragraph on Security and Stability… I’ll try to wait until it is safe spending time!