The Palabos-Java interface

Important: To get Palabos up and running, it is not necessary to compile the Palabos-Java interface. The Java interface is a useful extension which you will find useful to develop your Palabos applications more rapidly.

Since version 1.1, Palabos is provided with a Java interface which offers an access to the library to programmers lacking a C++ culture. The look-and-feel of the Java interface is very different from the C++ interface, and a separate user’s guide will be provided at some point for this library. In the mean time, this section provides a few instructions for compiling and using the Java interface.


Jlabos is a java wrapper of the CFD C++ opensource library Palabos It is now part of Palabos but optionaly compiled.



  • swig1.3
  • javac + java (for example openjdk-6-jdk
  • mpicxx (for example libopenmpi-dev
  • mpirun (for example openmpi-bin
  • python


  • octave
  • subversion
  • convert
  • inkscape


You need to have Palabos installed and configured. Short explanation: download Palabos

Define env variable PALABOS_ROOT. For example add this line in ~/.bashrc: export PALABOS_ROOT=~/location_of_palabos

cd $PALABOS_ROOT/jlabos/src edit the Makefile nbOfCore = 4 // Number of CPU core used to do the compilation. Do not specify more than you realy have or it will be very slow. swigCompiler = swig // you can specify an alternate swig executable includePaths = // specify the location of the file jni.h and jni_md.h

Compile Jlabos : cd $PALABOS_ROOT/jlabos/src; make This will take a lot of time because it will compile Palabos at the same time.

Running the examples

go to the choosen example directory and type make. This will compile and launch the program. You can customize some elements in the Makefile. Do not launch directly the SConstruct file. If you need to specify another place for the shared libs, edit the file launch accordingly.

To clean the directory, you can use make clean

See the result

If needed you can plot the results with Octave or Matlab like this: ./plot.m Jlabos can as well directly produce jpg files using the embeded library MLplot. See the examples code source. MLplot need the program convert from ImageMagick

Customize the wrapper

Jlabos is the Palabos wrapper but it is not complete. If you need more functionalities there are two places to go:

$PALABOS_ROOT/jlabos/src/jlabos => here you find high level java files that wrap to the autogenerated files here: $PALABOS_ROOT/jlabos/src/swig/pre_compiled => Swig generated files from the .i files present at the same place. Do not edit the java files here but instead modify the .i files and re-run the make process. But be warned, it’s not easy to obtain something that is working!

If the functionality that you want is present in the second place, you can modify the files in the first place to wrap nicely the self generateds java files.


│── examples
│   ├── Cavity2d
│   ├── Cavity3d
│   ├── Cylinder2d
│   ├── Cylinder3d
│   └── Porous
└── src
    ├── compilePalabos
    ├── jlabos
    │   └── plb
    │       └── jlabos
    ├── lib
    ├── plbWrapper
    │   ├── block
    │   │   ├── double
    │   │   ├── float
    │   │   └── int
    │   ├── lattice
    │   │   ├── d2q9_double
    │   │   ├── d2q9_float
    │   │   ├── d3q19_double
    │   │   └── d3q19_float
    │   └── utils
    ├── precompiled
    │   ├── floatOnly
    │   │   ├── double
    │   │   └── float
    │   ├── intOrFloat
    │   │   ├── double
    │   │   ├── float
    │   │   └── int
    │   └── lattice
    │       ├── d2q9_double
    │       ├── d2q9_float
    │       ├── d3q19_double
    │       └── d3q19_float
    ├── swig
    │   ├── pre_processed
    ├── testing
    └── util

Technical details

One part of the wrapper is generated using the Swig library (Simplified Wrapper and Interface Generator). This step produce not very usable Java files. This is why we had to write a second wrapper in Java to hide this first layer to the end user. Jlabos is not a complete wrapper for Palabos, but will evolve over time.

The directory compilepalabos is just a dummy project to force the compilation of Palabos


In the swig directory we have all the .i files needed by swig.

plbwrapper contains some Palabos wrappers written in C++ and used by swig.