Oracle's top brass might have committed to merging its Java technology with that of Sun Microsystems but the specifics are still being worked out.

The plan on how to merge Oracle's JRockit Java Virtual Machine (JVM) and Sun's HotSpot JVM is "still evolving", Oracle principal engineer Mark Reinhold has said.

Leads from two JVM's engineering teams are "spending lots of quality time together" Reinhold told an Oracle Technology Network webcast audience, but he admitted "it's not an easy problem taking the best of each [JVM] and figuring out the long-term convergence."

Reinhold, formerly of Sun, speculated that integration of the two to produce a single JVM probably wouldn't happen soon but might finally take place in the next year-and-a-half to two years.

The goal to integrate of JRockit and HotSpot was announced by Oracle as part of its strategy day in January, where managers laid our the plan for Sun's middleware and operating systems in the wake of Oracle's successful closure of its $5.6bn acquisition of Sun.

Oracle did not provide a timeframe for the JVMs' merger.

By planning to merge the two, Oracle's management has set engineers from Oracle and the former Sun the Darwinian task of picking the best features and dumping the rest.

What's unclear is whether that means keeping most of one application server and building in the best from the loser or building a new application server that combines both.

Reinhold noted Oracle is renowned for being willing to set aside its own technologies should it come across something better. It kept the former BEA's JRockit at the expense of its own Java application server, after all. "It's pretty clear, Oracle both engineering-wise and management-wise is committed to figuring out what the best is," he said.

Speaking personally, Reinhold said one option might be for a merged VM with the JRockit garbage collector and surfacabilty along with the HotSpot runtime compiler. Reinhold reckoned JRockit has enviable mission control - management - systems, while there was room for improvement on the server compiler, which HotSpot could provide.

You can see the full webcast here.