From: "Mauricio Fernández" Date: 2003-07-03T23:31:15+09:00 Subject: [ANN] rjni: Java binding for Ruby through JNI -- tech. preview [this message was first rejected by SpamAssassin :-) ] More information at http://www.thekode.net/ruby/rjni rjni: Java binding for Ruby through JNI Copyright (c) 2003 Mauricio Julio Fern�ndez Pradier WARNING: This is a technology preview. The software is not even alpha quality at the moment and is not meant to be used yet. It is only provided to present the techniques employed and (hopefully) to accelerate the development. Feedback: please don't hesitate to contact me to criticize, suggest new features or help with the development :) License For the time being, the same as Ruby. Might switch to LGPL in the future. Status * The APIs are quickly stabilizing. * The base layer still needs some work and further testing. * Several low-level issues remain to be solved. * The higher-level APIs have yet to be documented and tested rigorously. What is rjni? rjni exposes the Java Native Interface to Ruby. This allows the programmer to instantiate Java objects, manipulate them, define Java classes, etc.. from Ruby. Note that rjni is not meant to embed Ruby into Java, although it can be used to ease integration in that case. Building This technology preview is meant to illustrate the possibilities offered by rjni. It is by no means a usable library yet. The build process is quite tricky, as it involves linking against the Java libraries and is therefore highly system-dependent. The steps are: 1. creating the Makefile. This is done by executing ruby extconf.rb \ --with-jsdk-include=/usr/local/java/j2sdk1.4.1/include/ \ --with-jsdk-lib=/usr/local/java/j2sdk1.4.1/jre/lib/i386/ \ --with-jsdk-so-include=/usr/local/java/j2sdk1.4.1/include/linux/ You have to replace the paths above by the appropriate values for your local Java installation. Note that rjni has been tested with Blackdown 1.4.1, and, although it should be possible to build it with other JSDKs, compilation and/or linking might fail unless you get the above options right and/or modify extconf.rb itself (or end up modifying the Makefile by hand :) 2. Compiling make 3. You can now run the tests: ./tc_all.sh You will notice a short pause after the execution of the script. This is normal and expected at the moment. 4. High-level API demo: ./test_reflect.sh Problems Compilation Were you to experience difficulties when compiling, you'd have to make sure that the appropriate -rpath and/or -L options are passed to gcc. Execution Sometimes ld.so will be unable to resolve symbols at runtime; you will then need to set the LD_LIBRARY_PATH environment variable to some sensible value. APIs RJNI will have at least 3 APIs: * RJNI: a low-level straight-forward mapping of the Java Native Interface to Ruby. All operations on Java objects and classes are ultimately performed through this layer. * RJNI::Java: a direct conversion of java.lang.reflect and associated classes to Ruby. It is built upon RJNI. * RJNI::Reflect: magic reflection of Java objects to Ruby, such that they can seemingly be manipulated exactly like Ruby objects. This involves automatic method dispatching, singleton class abstraction (static methods become singleton methods of the class object), some automatic type conversions, attribute setters and getters, etc. -- _ _ | |__ __ _| |_ ___ _ __ ___ __ _ _ __ | '_ \ / _` | __/ __| '_ ` _ \ / _` | '_ \ | |_) | (_| | |_\__ \ | | | | | (_| | | | | |_.__/ \__,_|\__|___/_| |_| |_|\__,_|_| |_| Running Debian GNU/Linux Sid (unstable) batsman dot geo at yahoo dot com Linux: Where Don't We Want To Go Today? -- Submitted by Pancrazio De Mauro, paraphrasing some well-known sales talk