Java Native Interface

• Introduction:
  What is JNI? A java native interface provides a native interface between java and native C code. Essentially, this means that code written in Java can call and run C functions in a library. In virtual midtown, the client is compiled into a C library and Agents created in Java communicate to the server via the client code -- via the JNI.

• Current Status:
  The JNI has on major problem: Agents created in the JNI are not displayed by the viewer. The JNI calls functions within the client that handle the calls to the server. According to what we know of the viewer, the viewer needs the agent type, position, orientation, and velocity to display an agent. Our tests have shown that we are sending this information to the server and the viewer does receive this information. Based on this assertion, we believe that the JNI is completed and there is a bug in the client/viewer.

• Tutorial:
  Sun has an extremely good tutorial on JNI at this site:
  http://java.sun.com/docs/books/tutorial/native1.1/index.html

  Particularly of interest is the tutorial on Compiling and Running a Java Program with a Native Method:
  http://java.sun.com/docs/books/tutorial/native1.1/stepbystep/index.html

• Running and Compiling:
  • Compiling and Running on SGI IRIX (Fall 1998)
  • Compiling and Running on Microsoft Windows NT

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