[vwnc] [ANN] JavaConnect 2.0-beta available

Hi,

A new version of JavaConnect (2.0 beta) is available for download and  
use. All information on how to obtain and use JavaConnect is available  
on http://www.info.ucl.ac.be/~jbrichau/javaconnect.html (it is version  
1.114 in the store, or any later version marked 'development').

JavaConnect is a Smalltalk library that allows to seamlessly interact  
with Java objects from Smalltalk. The current implementation is  
available for Visualworks and a version for Squeak/Pharo is being  
prepared. Using JavaConnect, a Smalltalk application can access any  
Java object and send messages to it, just as if it were a Smalltalk  
object. Similarly, any Smalltalk object can be passed as an argument  
to a Java method. The first version of JavaConnect was developed end  
of 2006, early 2007, using the same basic mechanisms of the Visual  
Smalltalk JavaInSt and Dolphin JNIPort works. JavaConnect can be used  
to work with any Java library and it has been specifically used to lay  
a connection between Smalltalk-based code reasoning tools and a  
running Eclipse Java environment (http://www.info.ucl.ac.be/~jbrichau/penumbra.html 
).

Following a couple of years of slow incremental improvements, we have  
recently improved JavaConnect to version 2.0, featuring various  
novelties and upgrades.

Here are the highlights:
- JavaConnect 2 supports running the JVM in a separate OS thread,  
especially allowing Mac OS X users to use the Java AWT/Swing from  
JavaConnect. This particularity of Java for Mac OS X platforms  
requires specific treatment of the Java<->Smalltalk connection for  
each Smalltalk process through the Visualworks DLLCC threaded  
communication. JavaConnect transparantly manages this interaction.  
Unfortunately, such threaded communication is very slow, so you might  
want to use non-threaded communication if you do not need the Java GUI.

- We packaged a Java decompiler in JavaConnect which is used to  
decompile Java source code and show it when browsing the loaded Java  
classes from the refactoring browser.

- A more experimental feature allows to translate Java methods to  
equivalent Smalltalk methods, whenever possible. When Java methods  
merely invoke methods on the incoming arguments and when you pass  
Smalltalk objects to these methods, you can overcome a lot of the  
communication overhead by translating the Java method to a Smalltalk  
method, hence keeping the entire execution in Smalltalk. This feature  
already works for many methods but will gradually become more complete  
as we go on. Our goal here is to be able to 'shift' an entire object  
tree (such as a Java parsetree) to Smalltalk and disconnect from the  
JVM for subsequent reasoning over the parsetree. This is of course  
inspired by our principal use of JavaConnect (i.e. connecting to the  
Eclipse environment).

- Any Smalltalk object can be passed as an argument to a Java method.  
This means callbacks from Java into Smalltalk do not require any  
specific provisions from the Java side (except one limitation in the  
current version -- see later). Following the Smalltalk spirit, all  
will go well as long as the Smalltalk object understands the messages  
that Java sends to it. At this time, the limitation is that the  
argument type of the method (to which the Smalltalk object is passed)  
must be of an interface type since the mechanism relies on dynamic  
Java proxy generation. This limitation will soon be removed though as  
we work around this limitation of dynamic Java proxies.

Furthermore:
- Java packages are entirely mapped onto the Smalltalk namespaces,  
allowing to reference Java classes just like you reference Smalltalk  
classes.

- Java namespaces, classes and code can be browsed from within the  
refactoring browser.

- Smalltalk methods and variables can be added to the Java classes  
such that those methods and variables are visible and useable by the  
Smalltalk code. Using the integration in the refactoring browser, you  
can also publish these to a store (without the Java methods, obviously).

- A framework for selecting specific classloaders for specific classes  
can be used. This is, for example, necessary to be able to run Eclipse  
in JavaConnect and use its loaded classes in the Smalltalk environment.

- JavaConnect was implemented as a specialization of the Smalltalk  
MOP. This was an exercise to see how easy it would be to make Java  
classes appear like Smalltalk classes through subclassing the Class  
and MetaClass hierarchy. This has been useful for demonstrating the  
dynamic and reflective possibilities of a language like Smalltalk in  
the context of a course on reflection.

JavaConnect runs on Mac OS X, Linux and Windows.

Have fun using it and do not hesitate to contact me for any bugs or  
problems. This is a beta version, so there must be some ;-)

----------------------------
Johan Brichau
[hidden email]




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Johan Brichau schrieb:

> JavaConnect runs on Mac OS X, Linux and Windows.
>
> Have fun using it and do not hesitate to contact me for any bugs or  
> problems. This is a beta version, so there must be some ;-)

Hello,

where do JavaConnect and JNIPort differ?

As far as I can tell, both are using the javavm as dll hence JNI.


Cheers,

Claus
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On 25 Aug 2009, at 21:26, Claus Kick wrote:

Sure, the underlying technique is the same but there are still many  
differences.
I tried to summarize the important differences on the JavaConnect  
website:

http://www.info.ucl.ac.be/~jbrichau/javaconnect.html

best regards,

----------------------------
Johan Brichau
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