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From Dmitry Serebrennikov <dmitr...@earthlink.net>
Subject Re: Backward compatibility
Date Wed, 11 May 2005 23:27:52 GMT
I thinking you worry too much :) Maybe Sun is just making it all too 
complicated ;)

If nothing else, perhaps with some competition Sun will finally start 
fixing all those bugs in the bugparade that have been there for years 
and years (like flaky filesystem operations, weird out of memory errors, 
and the like). Just take a look how Microsoft has gotten off their ass 
once Linux has really became popular. VM can't be that much more 
complicated than an operating system, can it?


Gerry Steele wrote:

>I'm a big fan of the Apache foundation but this is one product I'm not too 
>sure is such a good idea as of yet for reasons several:
>>>Deprecated or non deprecated, we want Harmony to pass the TCK, so
>>>>whatever the TCK wants us to do, we'll do it.
>I hope you understand what sticking to the TCK entails. When it comes to 
>implementing GUI stuff for instance, your platform will have to fully copy 
>the official JVM's Swing/AWT widgets and all other details in order for the 
>automation and robot driven tests to pass. The JCK testbase for tiger is 
>immense. To get it setup and run is a skill on its own. To get it to pass 
>all tests takes a serious am mount of tweaking and a noteable knowledge of 
>the javatest harness. It will require implementations on things as extensive 
>as CORBA and RMI. We would need passive agents, tname servers etc.
>Also, when running the TCK bear in mind that you'll have to run the harness 
>with the Sun VM.
>I'm not sure about the particular extent of the testsuite provided with the 
>TCK you guys are talking about (if there is interest can find out more), but 
>the JCK, which is basically a TCK for the entire J2SE jre and jdk will be 
>going on impossible to pass for an alternative implmentation as everything 
>is written with the Sun JDK/JRE in mind and test cases are adapted in ways 
>that will create an infinite unpredictable series of problems when trying to 
>adapt your code.
>Another reason is that I'm not quite sure I see the point. It will take 4-5 
>years or more to even come close to a product like tiger. Sun are already 
>working heavily on mustang and dolphin (to a lesser degree on the latter). 
>As well as this, sun research have many projects looking at the future of 
>the Java VM such as the Barcelona project which will drastically change the 
>implementation of the JVM. For instance to make it more network orientated 
>or to improve resource sharing.
>The latter things (which are yet to see real sun implementation) might be 
>something you guys might then want to take advantage of in order to leverage 
>a selling point of Harmony. Without something like that it's just another 
>attempt at a VM that will be playing catch-up forever.
>Also, don't forget about quality. Sun put a serious amount of money and 
>manpower into ensuring the quality and compatibility of the JVM. A lot of 
>corporations depend on this. They have a regular update release cycle. For 
>instance we are currently working on 1.3.1_16, 1.4.2_09, 5.0_04 & 5.0_05.
>In a project of this size some of the the test suites take several days to 
>run. Some take many many hours of man power. For excessive thoroughness 
>there also manual JCK and regression test suites. Which, trust me, will not 
>be performed by someone who isn't being paid for it. Things like this don't 
>fit well with the community model. 
>Another worry I have is that the effort here might be better redirect to 
>some other project. We already have Java. Even if harmony does make it to a 
>useable release people will still prefer to use the Sun VM. It will be the 
>platform people build on and it will be the one they trust.
>I'll be very interested in how this turns out. 
>1) speed
>>2) portability (java is claimed to run 'everywhere', but in fact, it
>>runs only on a few operating systems, even fewer for 1.5)
>>3) configurability (I might want to tune it differently and, for
>>example, choose different thread/GC models)
>>4) implementation stategy (in macosx, multiple JVMs share 80% of their
>>memory, and some of Swing is native, therefore feels like the rest of
>>the OS and it's hardware accelerated)
>>5) internal modularity (we want diversity of implementation to drive
>>innovation in the VM space, both in and out companies and universities)
>>And, last but not least, if Sun or other vendors that already have JVM
>>want to stop paying for all that development on their and want to start
>>sharing the development costs with the java ecosystem in general and
>>with a clear warranty that we will not try to pollute the stream we all
>>drink from, therefore want to contribute some of their code to Harmony,
>>we will welcome them with open arms.

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