Efficient data transfer from Java to C++ on windows

Question

I\'m looking to stream lots of data (up to ~1 Gbit) from Java to a C++ application (both on the same machine). I\'m currently using a FIFO on Linux but need a Windows soluti

Answer 1

If it's a big chunk of data in "one" function call I would recommend JNI.

Take a look at this:Sharing output streams through a jni interface

Snippet from the article, it transfert data from c++ to java, the opposite would be also easy to do:

In all, the general strategy for sharing binary data (A/V files, images, etc.) from C with Java requires byte arrays. You create a Java byte array in C like this:

const char[] rawData = {0,1,2,3,4,5,6,7,8,9}; //Or get some raw data from somewhere
int dataSize = sizeof(rawData);
printf("Building raw data array copy\n");
jbyteArray rawDataCopy = env->NewByteArray(dataSize);
env->SetByteArrayRegion(rawDataCopy, 0, dataSize, rawData);

And pass it to Java like this:

printf("Finding callback method\n");
//Assumes obj is the Java instance that will receive the raw data via callback
jmethodID aMethodId = env->GetMethodID(env->GetObjectClass(obj),"handleData","([B)V");
if(0==aMethodId) throw MyRuntimeException("Method not found error");
printf("Invoking the callback\n");
env->CallVoidMethod(obj,aMethodId, &rawDataCopy);

you would have a Java object that looked something like this:

public class MyDataHandler {
  OutputStream dataStream;
  public MyDataHandler(OutputStream writeTo) { dataStream = writeTo;}
  public void handleData(byte[] incomingData) { dataStream.write(incomingData); }
}

That handler would be passed to C via native method like so:

public class NativeIntegration {
  public native void generateBinaryWithHandler(MyDataHandler handler);

  //Here we assume response is something like a network stream
  public void doCallNativeFunction(ResponseStream response) {
    MyDataHandler handler = new MyDataHandler(response);
    generateBinaryWithHandler(handler);
  }
}

Also, you can use other technologies: CORBA, ASN.1 (ASN.1 tool), UDP or TCP