The other is for a personal project, just a small game for some friends, that makes heavy use of an object tree for managing the game world. I’ve found that initial world loads from a database on system startup is tricky, because of the recursive nature of the hierarchical structure. I had seen the original MagLev demo and realized that it could provide a reasonable mechanism for reading and writing large object graphs like the one in my game from a persistent store on disk, clustered using Terracotta.

I see two main obstacles so far, but this is only speculation because I haven’t managed to get JRuby to work with Terracotta for anything other than POJOs and Java Strings (instantiated inside the JRuby Runtime).

First, JRuby objects should be persisted into Terracotta automatically while configuring Terracotta to ignore any references to the JRuby Runtime instance itself, or its class loader.

Second, “transactions” would have to be managed automatically for specific object operations or entire instances of classes. This could be configured either by possibly annotations or maybe a DSL. Or some convention could be arranged. Such transactions would require that a write operations requiring immediate consistency be completed for every Terracotta instance in the cluster, or at least for a “master” node where an application could go to get guaranteed consistent data. Unfortunately, that node’s SLA would be limited. Other nodes could be written to ASAP for eventual consistency in the system.

Certainly there are tons of issues that would need to be addressed for any system resembling a highly available and scalable application. But these things would be a start, and would allow two things: The use of a highly scalable platform for ruby web-application programming, and also the reduction of a traditional relational database model, which doesn’t lend itself to massively interconnected hierarchical trees of objects with highly variable typing.

Well, I didn’t think I’d wind up writing this much stuff in this comment. Thanks again for the work that you’ve been doing. It’s been inspiring and interesting. I hope it can soon be used for something very special.

Thanks for your comments! Unfortunately I haven’t had any time yet to play with this JRuby/Terracotta integration. Then, answering your questions, there isn’t a new version.

Regarding the TIM, I haven’t heard anything from the Terracotta guys. Probably there isn’t one yet.

I’m curious about what you are going to do with this stuff. Can you tell something about it?

I’m interested in using it with the latest version of JRuby (1.5.3), and I have two questions:

Is there a version available (or method for achieving the same) that does not require a patch to the JRuby source (since it is often changing)? That is, is there a way to simply programmatically specify particular ruby classes or – even better – individual ruby variables in the JVM for sharing across JVMs?

Is there a TIM yet?

Thanks in advance for your time, and well done with this project!

1) Unfortunately not in the next (1.1.5). There are things that must be tuned yet. I’ve already discussed a bit with Charles Nutter. The main points are: a) global object identity, b) shared metaclasses. But it is already usable.

2) Not yet. That is my next step; or perhaps I will open the source in github first.