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Can a native image generated by GraalVM replace IKVM generated DLLs?

I have some Java-app and a customer with some UWP-app implemented in C#, distributed through the Windows Store etc., who wants to use some pieces of my app. Those pieces are pretty OS-independent, only parsing of some special binary file formats, applying some business logic configured using YAML files and stuff. No network, GUI, only some accesses to files etc.
We currently use IKVM to make the code of interest available to C# but ran into different problems already. Some were supporting .NET Core, some had to do with the native toolchain in Release etc. While right now things seem to work after applying some workarounds, I'm looking for alternatives to IKVM already a bit.
The only thing I currently use of IKVM is simply creating a DLL of my code using ikvmc, which can then be referenced in the UWP-project. The compiler is summarized like the following:
The ikvmc tool converts Java bytecode to .NET dll's and exe's.
That's where the support to create native Windows images of GraalVM came into my mind. Others seem to already build native binaries for Windows and according to the docs, GraalVM is able to create shared libs using "--shared". From my understanding, IKVM implements a JVM in .NET and maps things as needed and possible. That sounds pretty much like what "Substrate VM" does in case of a native image, doesn't it?
This executable includes the application, the libraries, the JDK and
does not run on the Java VM, but includes necessary components like
memory management and thread scheduling from a different virtual
machine, called “Substrate VM”. Substrate VM is the name for the
runtime components (like the deoptimizer, garbage collector, thread
scheduling etc.).
https://www.graalvm.org/docs/reference-manual/native-image/
So, is there any chance that a native image in form of a DLL can replace the DLL created by ikvmc currently? Did anyone try that already and has any experiences? Did anyone try already to create a native DLL and consume that in some other native Windows app? From my understanding UWP "only" applies additional restrictions which one might be able to work around again. Or is this approach totally impossible for some reasons?
Thanks all for your input!

I'm not very familiar with the IKVM project, so this answer is mostly about the generic question:
Can you create a native DLL/shared library and consume that in some other native Windows app?
It should be possible. You can compile Java code into a shared library. The entry points are marked with the #CEntrypoint annotation.
You can then use the generated shared library and the header files to consume your library from a native application.
This way for example GraalVM distributions use the GraalVM JIT compiler by default:
The GraalVM JIT is written in Java
Compiled as a shared library with the native-image
Used in Hotspot.
Here's a page describing how to consume those from Java through the JNI: https://www.graalvm.org/reference-manual/native-image/ImplementingNativeMethodsInJavaWithSVM/
which could be very similar to how would you use a shared library from a C# application.

GraalVM native images are not very flexible, unlike IKVM.NET images. Unless you like writing wrappers and playing with P/Invoke, you should stick to IKVM.NET.
NOTE: I am behind an IKVM.NET fork

What is the easiest way to call Objective-C code from Java?

I need to access a list of Wifi devices on Mac OSX from Java code and after researching it, I've found that I need to resort to "native" code - namely the CoreWLAN framework and the CWInterface.h class (https://developer.apple.com/library/mac/#documentation/CoreWLAN/Reference/CWInterface_reference/translated_content/CWInterface.html)
I initially thought I would be able to call this code using JNA but realized that I needed something since CoreWLAN is Objective-C (not C/C++).
I've tried this Objective-C Java bridge (https://github.com/shannah/Java-Objective-C-Bridge) but I can't work out how to make it find the CoreWLAN framework.
So I've also tried using JNAerator (https://code.google.com/p/jnaerator/wiki/ObjectiveC) so I can I use BridJ (https://code.google.com/p/bridj/), but I can't make it generate the right Java code.
Just using this style java -Xmx1000m -jar jnaerator.jar -framework CoreWLAN -jar CoreWlan.jar runs quickly but results in a jar that only contains mappings for CoreWlan.h
If I run jnaerator against CWInterface.h then jnaerator fails.
(I'm using the latest snapshot version of jnaerator)
What is the best way to call methods on CWInterface.h from Java?

What I would do is create a C++ class that communicates with the Java code through JNI. You can use both C++ and Obj-C in your xCode project. I haven't tried myself to use a Obj-C++ class with JNI, but I would just create a C++ class responsible for all communication between Java and Obj-C, this class can just be included in the Obj-C class where you need it (change the extension of this Obj-C file to .mm since it'll include C++ code).
I found this a helpful article on JNI: http://www.ibm.com/developerworks/java/tutorials/j-jni/

Personally I would do this via two totally separate programs that communicate via a shared memory mapped file. One program written in straight Objective-C, and the other in straight Java.
Memory mapping would mean that both programs would have access to the same region of memory, without having to resort to JNI at all.
Notes on memory mapping from Java:
http://javarevisited.blogspot.co.uk/2012/01/memorymapped-file-and-io-in-java.html
Notes on memory mapping from Objective C:
https://gist.github.com/jverkoey/2985830
That said, if you do want to do go the JNI route, then Apple has the following advice:
It is recommended that you use the Java JNI template in Xcode as a starting point for your JNI development.
To interoperate with the Objective-C runtime from JNI, link against JavaNativeFoundation.framework, which
is a sub-framework of JavaVM.framework. It contains Objective-C classes and macros to automatically set up
and tear down autorelease pools, catch and re-throw Java and Cocoa exceptions, hold JNI global references
in Foundation container classes, and convert object graphs of strings, numbers, lists, maps, and sets.
The above quotes were taken from here:
https://developer.apple.com/library/mac/documentation/java/conceptual/java14development/Java14Development.pdf

You can use the java objective-c bridge for this. You just need to load the framework you want to use with jna's Native.loadLibrary() method.
This example uses the WebKit framework. https://github.com/shannah/Java-Objective-C-Bridge/blob/master/java/test/ca/weblite/objc/TestWebView.java

Java Projects on Django?

ok, So i searched net for the possible implementation but all that I managed to find is Django projects implementation on Java platform through Jython. But I want to do the reverse, i.e. implement/integrate java project ( which in my case is SAIKU server ) on Django platform.
The question being, is it possible, and if yes, then kindly point me to the solution.
Thanking in advance =)

For your specific requirement, I would suggest using RESTFul API to access the Saiku Server.
However if you need to run Java Classes from Python.
Here are the options available for you:
JCC -- a C++ code generator for calling Java from C++/Python. It produces producing Python extensions which communicate via JNI with a Java virtual machine. As it implies, this would require compilations of every possible call. However this project is backbone of PyLucene project.
CodeMesh. C++ code generator for Java.
Py4J Python programs running in a Python interpreter to dynamically access Java objects in a Java Virtual Machine.
JPype allow python programs full access to java class libraries. It is done through interfacing at the native level in both Virtual Machines. However there are no recent development in this front.
In general, having an loosly coupled integration through REST or RCP would be easy to maintain than tightly coupled JNI based implementation.

There's no way to run Java within the Python runtime (which is what it sounds like you want). There are Java to Python "translators" available, but they're terrible. Honestly, if you need a Java server and Django to sit inside the same process for some reason, Jython is the way to go.
There are lots of options outside of that though, off the top of my head:
Implement Python bindings for your server (See PyLucene for an example)
Implement a socket server within your Java server that Python can talk to directly

How to use the WinInet API from Java?

According to this answer to an earlier question of mine, the WinInet Windows API is the correct way to read and write internet connection settings in Windows. How can I use this API from Java? I'd prefer a free, open-source solution.

There's always JNI and JNA, but if you don't already know C or C++ there'll be a learning curve involved, especially with JNI: JNI Reference, JNA Site

Over the last months I had to mix with my Java project some C, C++ and Win32 alternatives for native access. After a lot work with JNA and recently with JInvoke for such integration, I can tell you that JInvoke is a little mature than JNA. Even JInvoke be older than JNA, I found its syntax more concise and simple. Sorry for those who loves JNA but using JInvoke I could literally hook the windows api from Java.

I see there's a commercial library called JInvoke that:
enables Java developers to easily
invoke native methods (such as the
Win32 API or C-based Windows DLLs and
Unix dynamic libraries) with pure Java
code.
However I'd prefer something free and specifically targetted at the WinInet API.

Have a look at JACOB project
JACOB is a JAVA-COM Bridge that allows
you to call COM Automation components
from Java. It uses JNI to make native
calls to the COM libraries. JACOB runs
on x86 and x64 environments supporting
32 bit and 64 bit JVMs
http://sourceforge.net/projects/jacob-project/

Calling Java library from Objective C on Mac

I want to create native Mac OS X application using Cocoa + Objective C but I need to connect to proprietary data source, and for this, owner of the data source only provides Java library. So I need to somehow import this Java library into my project and call functions on its Java classes.(Or create java wrapper around this library and then call my wrapper from objective-C).
Now, how can I do this? Quick google search leads me to JNI but I haven't found any good and actual(current) article/tutorial. I would really need some HOW TO article, how to load this java library, start VM if needed, and how to create java objects and call functions on them. Really something simple and I can move from there. Thanks.
Just to clarify, I repeat: I WANT to call Java functions from Objective-C, I do NOT want to call native functions from Java.

You're probably looking for the Invocation API, a little-known corner of Java Native Interface (JNI) which allows you to load the Java runtime in-process.
That said, you might have an easier time of it with a Java service application that communicates with your Objective-C application over network sockets.

You're looking for the Java-Objective C bridge, try looking at this article or on Apple's developer site. Be aware it is deprecated, that is it isn't being kept up to date with changes to Cocoa. But if you're just using it for an API passing standard Java datatypes you should be OK.