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Java applications on embedded Linux

 
Tom Stevns
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Hi Eric Giguere!
I am special interested in Java applications on embedded Linux, so please give me some hints to this topic.
Besides that:
What kind of professional platforms use this ?
Does it discuss why Java 2 Micro Edition (J2ME) it's needed ?
Is there some VisualBasic alternative ?
What about configurations and profiles that make up J2ME ?
How to use J2ME implementations and which industrial areas has already J2ME for some time ?
Waba what is that?

thanx in advance
Tom Stevns Nielsen, SCJ2P
 
Valentin Crettaz
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I am special interested in Java applications on embedded Linux, so please give me some hints to this topic.
Do you mean something like running Java applications on an iPaq running a "lightweight" version of Linux like Familiar or Intimate?
If this is the case, just know that Blackdown has released a JRE port (1.3.1) for StrongARM processor and that applications developed using J2SDK 1.3.1 run on iPaqs without any problem (from my experience). The advantage is that you get a complete J2SE support (Swing, Networking, sql, ...).
 
Shuai Liu
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Hi Valentin,
That's a great news! Does this virtual machine require certain model of iPaq(3765 or higher, for example)?
Also, do you know any java virtual machine for Windows CE that support full version of J2SE?
The only JVM for CE I know is EVM from Jeode. It supports only JDK1.1.8.
Thanks a lot.
 
Valentin Crettaz
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No, the only requirement is a JRE distribution for StrongARM processor like the one provided by Blackdown. So any iPaq does it as far as I know. I haven't tried other StrongARM devices, though.
I'm sorry, I don't know about a JVM for WinCE (and I don't wanna )
 
Shuai Liu
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Thank you!
I just browser throught some other forums and ppl there complain that that blackdown JRE is too slow? Do you feel the same way?
Do you mind telling me what kind of java application you have run on ipaq using that JRE?
Thanks a lot!
 
Valentin Crettaz
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Our application is a distributed group communication application using encryption. At the beginning, we saw some performance penalties. I did some profiling and discovered that the crypto stuff were hungry (no kidding... but only crypto, Swing and the rest were fine). I then developed a native implementation of the crypto part and everything was fine again... The application runs fine... About 20000 lines of code and it comes up in like 4 seconds... Nothing to complain about...
 
Shuai Liu
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Great! I think that's enough for my application which is going to be much smaller. Also, what about the earlier version of this JRE? I noticed this one is still a release candidate. Maybe that's one of reasons why it is "not fast" ?
Do you have experience in JXTA? Can we install that on embedded Linux such as familiar?
What about JINI?
Thanks for your time.
 
Tom Stevns
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Hi Valentin !
Thanx for the info about the strongArmProcessor.
unfortunately you are and vice versa when
I write this mail.
regards Tom Stevns Nielsen
Systems Architect
TietoEnator Consulting - Denmark
 
Tom Stevns
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Hi Valentin !
What kind of java-crypto did you use ?
 
Valentin Crettaz
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Tom,
why would I be embarassed? (according to the smiley you used...) Or do you mean asleep?
We used Cryptix which works very fine. We are using very large numbers and the only problem we have is that Sun's java.math.BigInteger implementation is 100% Java and too slow (on the iPaq), so I had to implement a native version of java.math.BigInteger in order to speed things up.
 
Tom Stevns
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Hi Valentin !
I ment asleep taking GMT +1 hour
in consideration.
 
Tom Stevns
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Hi !
Has anyone used bluetooth ?
 
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