Re: [xmlvm-users] Supporting native methods + Apache Harmony Java Runtime implementation

[Arno P. <ar...@pu...>]

certainly an interesting idea. I would caution against cross-compiling 
everything from Harmony. I haven't looked at their implementation but I 
would suspect that classes like String, ArrayList, HashMap are 
completely written in Java. Cross-compiling these would result in a 
severe performance penalty, that is why we currently map them (via 
categories) to their Objective-C counterparts (NSString, NSArray, 
NSDictionary). But I'm sure there are many other cases where 
cross-compiling Harmony would make a lot of sense.

Lets begin by discussing a JNI-like interface for Objective-C. That is 
something we need anyways at some point. Once we have that, we can 
discuss which parts of Harmony we cross-compile.

Anyone want to chip in with ideas regarding JNI for XMLVM?

Arno


Gergely Kis wrote:
> Hi,
> 
> We are porting a fairly complex J2ME / Android application to IPhone 
> using XMLVM, and I had an idea to speed up the process. Instead of 
> implementing every necessary class from the Java Runtime by hand, I 
> pulled in the Apache Harmony runtime implementation from the Android 
> platform and got to the point where it compiles to Java Bytecode. Now 
> XMLVM happily produces cross-compiled Objective C code from it, but of 
> course there are a number of native methods that need to be implemented. 
> XMLVM treats native methods simply as abstract methods.
> 
> The idea is to change the XSL, so it generates a dummy body for the 
> native methods, probably throwing an UnsupportedOperationException() or 
> something similar.
> Then for those classes that are actually used by us, we can go ahead and 
> implement the native methods using the nice "Categories" feature of 
> Objective-C, without the need to touch the generated source code.
> 
> Of course, we plan to use the hand optimized versions of those classes 
> that are available. For low-level classes, like threads, we plan to 
> implement the Thread class directly using NSThread. But there are many 
> classes, that are seldom used (exceptions) or are only interfaces, or 
> simply they are not yet available in a hand optimized version. In these 
> cases we are able to fall back to the cross-compiled version.
> 
> What do you think?
> 
> Would you be interested in this solution?
> 
> Best Regards,
> Gergely
> 
> -- 
> Kis Gergely
> MattaKis Consulting
> Email: ger...@ma... <mailto:ger...@ma...>
> Web: http://www.mattakis.com
> Phone: +36 70 408 1723
> 
> 
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