Does anyone have a good solution for integrating some C# code into a java application?
The code is small, so I could re-write in java, but I would rather reuse the code if possible. Don't repeat yourself, etc.
Also, I know I can expose the C# as a web service or whatever, but it has some security/encryption stuff in there, so I would rather keep it tightly integrated if possible.
Edit: It's going to be on a server-based app, so "downloading" another runtime is irrelevant.
You would use the Java Native Interface to call your C# code compiled into a DLL.
If its a small amount of C#, it would be much easier to port it to Java. If its a lot, this might be a good way to do it.
Here is a highlevel overview of it:
http://en.wikipedia.org/wiki/Java_Native_Interface
Your other option would be to create a COM assembly from the C# code and use J-Interop to invoke it.
http://sourceforge.net/projects/j-interop/
I am author of jni4net, open source intraprocess bridge between JVM and CLR. It's build on top of JNI and PInvoke. No C/C++ code needed. I hope it will help you.
If it's short, I think you're better off re-writing the code in java. Downloading one 50Mb runtime is bad enough.
There is an IL to Java Bytecode compiler GrassHopper which may be of use to you. I've never tried it though.
I'd look at rewriting your code in Java though
EDIT: Note that Grasshopper seems to be no longer available.
We used JNBridge for this, and it worked great. It handles Java->.NET and vice versa, all in-proc.
If you do not want to rewrite hadle it as an Inter-process communication and choose one of following:
Named pipes
Sockets
SOAP
I would rewrite it if it's not too much trouble.
The web service would work, but it seems like that would be a lot of overhead just to reuse a little code.
http://www.infoq.com/articles/in-process-java-net-integration suggests running CLR and JVM in the same process space and passing calls back and forth. It sounds very efficient. I'm going to give it a try and integrate it into Jace if it works well.
If it is a piece of code that is exposable as a command line utility, I just make the other host language use a system call to execute the utility.
If your C# app needs to call Java, compile a special Java main that takes appropriate command line args and returns text output.
It the oldest, simplest method.
You can call your c# classes (compiled in a dll) via a bridging library, various libraries are available, every one with his characteristics. JNBridge generate proxy classes that you can call to manage the code in java classes. JCOBridge let you load your c# classes and use it from java using the invoke mechanism, also javonet let you import java classes and call java code using the invoke mechanism. All the explored solutions are commercial solutions that let you call java code from .NET and vice-versa with graphical user interface integration and other amenities.
Links:
jnbridge java-.NET bridge Developer and Deployment license schema with 30 day free trial
jcobridge java-.NET bridge Developer and Deployment license schema with unlimited Trial
javonet java-.NET bridge Research and Professional license schema with 30-day unlimited Trial after sign-up
Related
I want to create a deskband COM object for my pet project. I don't have any experience with COM and a quick search revealed that ATL will simplify things. I was wondering if there are any better ways to create a COM component today. Better in the sense less boiler plate, use of C# instead of C++ and any other things you may think of.
If deploying or relying on a .NET framework installation on the client machine is not an issue for you, than C# is much easier than C++ (although you will probably have to redeclare interfaces, IID, etc... in C#, using P/Invoke). If reducing dependencies is an issue, than C++ with ATL is better.
Just create it in C# and expose as a COM component, see this guide:
http://msdn.microsoft.com/en-us/library/zsfww439.aspx
The only reason I would consider C++/ATL is if I were connecting to any C/C++ libraries. Other than than I can't think of a strong reason to use C++ over C# (assuming your skill level is equivalent in both).
I can only recommend C++ in conjunction with Microsoft's ATL library.
I used some code generation tool written in C++ that helped me to get rid of quite a lot of boilerplate code. This tool generated code that produced more C++ friendly interfaces (like the code that gets generated in the tlh/tli files when you #import a type library in Visual Studio. My code generator produces similar code, only for COM servers.
If you are interested, send a mail to DerTopper at web dot de. Put something like "COM code generator" in the subject line, so that you won't fall through my spam filter.
Regards,
Stuart
I have a game server which is made in Java. I want to make a plugin system that loads a .NET DLL and calls events / functions inside that DLL, then inside those I'll have to call functions in the game server (Java). The only part that is giving me trouble at the moment is how to interface java and a .NET dll.
I've been searching and found some things but they were all based on products and I want to make my own interface for that. Ah, not to mention it needs to have high performance, the code will be called a lot of times in a second if it has to. Could someone point or give-me ideas how could I work this out?
EDIT:
To make it more explicit:
Game Server (Java application) calls a function in .NET dll
The .NET function just called by java, calls multiple functions from Game Server (Java Application).
Take a look at jni4net if you're targeting Windows. It's an alpha quality release, but Robocode already uses it to run .NET robots inside the Java runtime.
Another option is to use a high-performance messaging approach. You'll need a second process - likely a .NET plug-in host. That process then exchanges messages with the main Java game process. Messaging libraries like 0MQ are pretty darn fast but may not be fast enough for what you have in mind. In addition, you'll have to create a lot of message plumbing which may be cost/time prohibitive.
Try using iKVM:
IKVM.NET is an implementation of Java for Mono and the Microsoft .NET
Framework. It includes the following components:
A Java Virtual Machine implemented in .NET
A .NET implementation of the Java class libraries Tools that enable Java and .NET
interoperability
http://www.ikvm.net/
If you only have a few methods you are calling you might just use JNI and do it yourself instead of a 3rd Party tool (though I admit I don't know the details of jni4net). Just a word of caution, the project I'm on had to do a similar thing (C# -> C/C++ -> Java via JNI) and we had nothing but problems with it. Problems mainly because the java api didn't have any good documentation so that might have been part of it. If at all possible try to keep it to one language but if that is not possible, make sure you do lots of error checking. When the app crashes, it is very hard to find the problem (unless you own both the java and C# sutff). Just my $0.02...
Is following thing possible?if yes how?
I have some core functionality already implemented in Java. Now I want to create a GUI for it.
I am finding it difficult to make a GUI in Java using Swing. I can build a GUI easily in C#.net.
So I was thinking if it was possible to create a library in Java that I can access from my C# code.
Shorty: my java code will provide some API and then my C# program must be able to call those APIs.
How do I do this?
Assuming you have properly structured your Java code, creating a Web Service bridge between the two could be the way to go. For example you could expose the Java API through a SOAP and simply make the C# UI depend on that.
The great side in this solution of course is that if you do it this way, you can replace the UI completely at any point you want to, downside is that you would have to run the Java part separately in a context such a servlet container which may be quite heavyweight for your needs.
Depends on what your java library does and if it uses many third party components, but thanks to IKVM you could compile a jar file into a .NET assembly. I've used this approach to incorporate the xhtmlrenderer java library into a C# application with success.
Yes, this is possible.
Have a look at JNBrige: http://www.jnbridge.com/
But, to be honest, I think it would be better to rewrite your APIs in .Net. Makes it easier in the end imho. I prefer working in one environment and not having to maintain things at different places.
have you considered using webservices? You could also execute a java program using something like:
private void calljava(object ob,EventArgs arg)
{
Process.Start("j.bat");
}
There is also JNBridge
Just a few ideas....
Having my own Java code I'm using C# to call some unmanaged code that call (via JNI) the java code. I'm using JNI since I need to ensure:
the ability that the Java code will run over real JVM and not over some .NET VM
the ability to attach to the VM for debugging (IKVM does'nt support it)
I need free solution
The current free solutions are not applicable (e.g. IKVM)
Anyway, my question is how can I manage strings passed between these layers in the best manner without leaks.
I'm doing something like:
[DllImport(#"MyDll.dll")]
public extern static void receive_message(string receDest, StringBuilder response);
This means I'm allocating the memory for the response in the managed code.
I want to avoid that since I don't know in advance the response length. How can I write a JNI appropriate method that will allocate the right buffer for the managed code without leaks. The JNI code should be thread safe.
Any suggestions?
Thanks,
Guy
You may need JNI, but your requirements don't really indicate it.
The requirement to use a real JVM does not dictate the use of JNI. I'd suggest sharpening your requirements, or considering looser coupling. For example, socket comms, web services, a shared database, a shared file, or a queue.
If you really need Java and .NET to be run in the same process, with tight coupling, consider JNBridge.
They've solved the problem you are confronting.
You might be interested in trying to convert your Java bytecode code in .NET CIL with IKVM.NET.
You essentially need to make a remote call into the java program from your .NET-code.
With your current skillset I would suggest that you create a web service in the Java machine - this is relatively easy in Java 6 - and based on the WSDL create a client in your .NET program.
This is probably the cleanest solution with todays technologies.
If that for some reason isn't good enough, then add to your question.
Guy -- Regarding Cheeso's response, and your respones to it:
JNBridgePro does allow the JVM to be started automatically and run inside the .NET process (in addition to the option of starting it explicitly). See the "shared-memory" communications mechanism discussed in the documentation.
JNBridgePro does allow you to attach a Java debugger, even when the JVM is running inside the .NET process. Contact support#jnbridge.com for details, as well as for details on configuring the JVM.
Can't do much about it not being free, but it might be worth your while to check it out anyway.
Disclosure: Yes, I am with JNBridge.
I think you could use jni4net as a bridge library. Or you could just look at source code and grab some ideas (LGPL/GPL).
Can you run C# code from c++?
and How?
If you're C++ code is "managed" C++ that's built on the .NET common language run-time (CLR), then it's easy to reference a C# assembly and invoke public classes and methods. If, however, your C++ code is "native" (not built on the CLR), then you'll want to register your C# assembly for COM interop and invoke the COM object from your C++ code. There's an MSDN article that covers all the gory details:
http://msdn.microsoft.com/en-us/library/w29wacsy(VS.80).aspx
There's also a good article on CodeProject by Nick Parker called "Exposing .NET Components to COM" that you may find useful.
You can use unmanaged C++ to run a .NET application, but how difficult it will be will depend on which version of .NET you are using.
When I did this with .NET 2.0 it took me two solid weeks to get it working.
The answer in this page gives guidance as to which programs are needed to do this.
http://www.pcreview.co.uk/forums/thread-1225474.php
The other option that you have, depending on what you're trying to do, is to host the CLR in your application which allows you to more tightly integrate the C# code than is possible by going through COM. You can read an overview of doing this in this MSDN Magazine article.
With C++/CLI, yes (formerly Managed C++ -- which had different extensions to the language).
yes, you can use COM to call .NET
You can call .NET code without COM by using the mscoree.dll ClrCreateManagedInstance Function. You need to supply the assembly qualified name of the type name you want to create, in the pTypeName parameter.
From memory, in some cases you may need to add the ComVisible attribute to the interfaces or classes you wish to access using ClrCreateManagedInstance(). However this does not require you to also register your class or any of the other messy deployment issues that go with COM.
I'm guessing the answer that would really be useful to Chad is:
Yes, it is most definitely technically possible to run C# code from C++. However, if the other answers on this page sound like they are going over your head, then you are nowhere near experienced enough to actually do this. It is pretty difficult to pull off, all things considered, so unless you really need to be running C# code from C++, it might be best to just rewrite the C# code as C++.