Treffer: JNI – C++ integration made easy

The Java Native Interface (JNI) [1] provides interoperation between Java code running on a Java Virtual Machine and code written in other programming languages (e.g., C++ or assembly). The JNI is useful when existing libraries need to be integrated into Java code, or when portions of the code are implemented in other languages for improved performance. The Java Native Interface is extremely flexible, allowing Java methods to invoke native methods and vice versa, as well as allowing native functions to manipulate Java objects. However, this flexibility comes at the expense of extra effort for the native language programmer, who has to explicitly specify how to connect to various Java objects (and later to disconnect from them, to avoid resource leak). We suggest a template-based framework that relieves the C++ programmer from most of this burden. In particular, the proposed technique provides automatic selection of the right functions to access Java objects based on their types, automatic release of previously acquired resources when they are no longer necessary, and overall simpler interface through grouping of auxiliary functions.