JavaSpaces Still Alive
I've long watched the JavaSpaces and Jini community because it is such a great technology, but sadly from a work experience standpoint, I haven't had a chance to really get my hands dirty. That's still the case, but I have new hope. JPower has released a free (as in beer) JavaSpace JMX component. It runs in any JMX container. It offers hot deployable JavaSpaces, backed by persistent storage via JDBC, and optional security via SSL. Coming in the next release is a Jini services container.
This is a really great (and subversive) idea. I wish I'd thought of it. I'm noticing a lot of work down below the level of J2EE. In some sense, it seems that J2EE has been developed backwards. Servlets came along first which is at the presentation layer, later EJB's came along for business logic. Next came CMP Entity Beans warts and all. Now JDO seems to be taking over the mindshare for persistence. However, the lower layers of infrastructure came later, or at least showed up with very little visibility. JNDI is an important layer that showed up with EJBs. Later came JMX, and then app server vendors worked furiously to build the foundations of their products on JMX. That's where the real low level foundation exists today. Aspect Oriented techniques (or Interceptor oriented if you prefer) are being using to more modularly implement much of these underpinnings.I also hear that Jini is even being used in some places for clustering of the app servers.
The subversive part (and I use that in the fondest sense) is now using JMX to get JavaSpaces and Jini in the picture as peers of the JMX managed web and EJB containers. JPower is the first I've heard of this, but I'll bet it won't take long for other vendors to do the same. Later on Sun might even catch up and make them part of the J2EE spec.
I'm excited that this might be the first step taking JavaSpaces and Jini to the mainstream. Go JPower!