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Explore IBM Java 7

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34 pointsjavinpaul9 comments

My impression is that aside from platform support, the major difference between the Oracle and IBM JVMs is their garbage collector. Is there someplace that has a definitive comparison (as opposed to just a rough description of each one's techniques)?

IBM also has a realtime jvm, metronome (aka "websphere realtime"): http://www.youtube.com/watch?v=jid4WaILPBk

I'm not familiar with this. Did IBM fork Java when Oracle bought Sun? If so why isn't Oracle going after IBM for "losing them billions of dollars", like when they went after Google?

"Did IBM fork Java when Oracle bought Sun? If so why isn't Oracle going after IBM"

IBM has had their own JDK implementation for more than 15 years. April 6th 1997 is about as close a date as I can find: http://www.os2ezine.com/v2n7/javarev.htm (that's version 1.0.2, so it's probably even earlier).

IBM have a license and produced a fully compatible implementation. Before Oracle bought BEA (who bought JRockit) there was also another independent commercial JDK implementation in addition to the IBM and Sun/Oracle ones.

IBM licensed it so they could optimize Java for Z, i-Series (aka AS/400), p-Series (AIX) and WebSphere. A decade ago, it performed much better than Sun Java in many respects.

There used to be licensing restrictions as well -- I think on x86 it was theoretically only free to run on IBM hardware or with other IBM software (ie. WebSphere, DB2, Tivoli, etc).

If so why isn't Oracle going after IBM for "losing them billions of dollars", like when they went after Google?

It's my understanding that Sun had a number of patents specifically for using Java on mobile devices that don't apply to non-mobile devices.

I think IBM has licensed Java for years and built their version in compliance with that license.

No, the IBM JVM has been around for ages.

HP also has their own implementation I believe

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