C++ To Java RPC Stub Generator

About

This project is an automatic stub generator for C++ to Java RPC (remote procedure calls). It uses Java reflection to automatically produce server(Java) and client(C++) stubs. Also included in the project are basic C++ and Java RPC libraries that are used by the stubs. Currently tested on Linux with JRE 1.6.

Sample code

This sample shows usage of the java.lang.StringBuilder class in C++:

java::java_lang_StringBuilder o(&conn);

o.append(std::string("Hello World!\n"));
o.append(256);
o.append(1.12345f).append(23456.789).append(-1000); /* Method chaining supported. */
o.append(-1000);
o.append(0);

std::vector<uint16_t> chars;
chars.push_back('g');
chars.push_back('i');
chars.push_back('t');

o.append(chars, 1, 2); /* Arrays supported. */

std::cout << o.toString() << std::endl;
std::cout << o.reverse().toString() << std::endl;

License

The project code is licensed under the permissive BSD license. Generated files remain the property of the people generating them.

Current Issues

Two or more dimension arrays are not supported by the RPC libraries. If you generate stubs for a class containing methods that take or return two or more dimension arrays, you will have to go into the stubs and comment out those methods.
In/out arguments are not supported.
No way to tell whether a string is null or empty.
No way to tell whether an array is null or empty.
No way to pass in null object reference.
Warnings produced in Java stubs (unchecked and rawtypes).

Dependencies

The C++ RPC library uses socket communication as well as strong and weak pointers. These can either be provided by the C++ Boost library or the Qt framework.

Using

The project contains three java projects (the generator, RPC server library and a sample server) and one C++ project (RPC client library with sample usage).

First build the Java server RPC library and export as a JAR.
Build the Java generator and export as a JAR.
Import these JAR files into the Java sample server, build and run either SampleGeneratorUsage.java or SimpleServer.java
Compile the C++ project using (on Linux) g++ -I /home/user/boost_1_46_1/ *.cc -lpthread -lboost_system (with the cpp directory as cwd).
You can also build the C++ project using Qt. A Qt project file is included.
You can now run the C++ sample project.

Types

The following types are supported:

Java Type           C++ Type
number              int8_t, int16_t, int32_t, int64_t, float, double
char                uint16_t
java.lang.String    std::string in UTF-8 format.
object              generated object stub
array               std::vector<array_type> eg. std::vector<int8_t> for byte[]

Exceptions

Exceptions thrown in the Java stubs are propagated back to the C++ client. The exception thrown is always a java::java_lang_Exception. However, one can use the instanceOf operator and casting constructor to cast to supported exception types. The following code sample demonstrates this:

try
{
	o.append(chars, 5, 3);
}
catch(java::java_lang_Exception e)
{
	e.printStackTrace();
	if (java::java_lang_Throwable::instanceOf(&conn, e))
	{
		java::java_lang_Throwable throwable(e);
		std::cout << throwable.getMessage() << std::endl;
	}
}

Performance

This project favors correctness and ease-of-use over performance. Therefore, some performance anti-patterns are used such as returning std::string and std::vector on the stack.

Security

The project is intended to be used only with trusted clients.

danfickle/cppToJavaRpcStubGenerator