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Reggie

Reggie is Sun's sample implementation of the core service in Jini, the service registrar. We can be short about it, because its behavior is fully described by the interface definitions in the Jini standard: it registers services, removes registrations when leases expire, and performs the multicast protocols so that it can be found.

Like the RMID, Reggie uses a log file (in the sense of a transaction log) that keeps the state between invocations. If you start Reggie as an activatable service (the default and documented way), you don't need to restart Reggie anymore unless you remove either one of the RMID or Reggie log directories.

Mahalo

The transaction manager that Sun implemented is called Mahalo. It implements the Jini TransactionManager interface but not the NestableTransactionManager interface because it doesn't support nested transactions. It reuses the code in Reggie to write transaction states to disk, so that transactions survive crashes and subsequent restarts.

There is no hard evidence that Mahalo is a high-performance transaction manager, and the Jini team certainly didn't make performance their primary aim. However, there is anecdotical evidence that Mahalo holds up well in transaction processing intensive environments, and as it seems a very stable product there's nothing against starting projects with the relatively light-weight Jini transaction specification.

Mahalo is an activatable service, so as long as you keep its log directory and RMID's log directory in tact, you don't need to restart it.

Outrigger

Outrigger implements the JavaSpaces specification. There are two ways to start it: either as a "transient" space or as a "persistent" space. Persistent spaces are useful for mini-databases, but updating the storage slows it down and as they run as activativatable services, they're a bit harder to start. Transient spaces are useful if the results of a crash aren't devastating (the contents of the spaces can be restored some other way) and performance is a prime concern.


 
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